Few European Hunter-Gatherers Survived Last Ice Age

The last ice age peaked at 20,000 years ago.  The people who survived in pockets of survivable territory started to repopulate Europe in the period from 14,000 to 7,000 years ago, called the Mesolithic era.  Several ancient genomes are now available from that era.  They suggest that the effective male population size prior to the repopulation of Europe was just 30 men.

Thus, modern humans only barely hung on through the Ice Age in Europe, and ultimately, their ancestry makes up a fairly modest share of modern European ancestry.

The Latest Combined Higgs Boson Mass Measurement From The LHC

The most up to date available measurement of the Higgs boson mass combining ATLAS and CMS experiment data in two different channels each at the end of the first LHC run to get a single number is:

125.09 +/- 0.237 GeV/c^2.

Analysis

The two sigma range for the Higgs boson mass is now:  124.61 GeV to 125.56 GeV.

This is a material improvement in the margin of error, which had previously hovered around 0.4 GeV.  Some further improvement in the margin of error should come from the second run of the LHC.

This value disfavors the 2H=2W+Z mass formula by 3.7 standard deviations.

There is an argument that the "tree-level" mass of the Higgs boson is 123.114 GeV (half the Higgs vev) but that it is increased by higher order loop corrections that bring it to its experimental value.  The "tree-level" estimate of the mass of the W boson is 78.9 GeV.  If the percentage increase in mass due to higher order loop corrections for the Higgs boson from the tree level value is the same as the higher order loop corrections of the W boson to the experimental value, then the implied Higgs boson mass value would be 125.43 GeV which is consistent at a 1.4 sigma level with the latest combined mass measurement.  No published source actually calculates these higher order loop adjustments, however.  While the actual higher order loop calculation is probably of that order of magnitude, it could easily be higher or lower.  The claim is plausible, but requires further investigation.  If the higher order loop corrections produced a value consistent with 124.65 GeV, that would be remarkable indeed as discussed below.

The hypothesis that the sum of the squares of the Higgs boson mass, W boson mass and Z boson mass equals half of the Higgs vev (using a global fit value of 80.376 GeV for the W boson mass) implies a Higgs boson mass of 124.65 GeV, which is within two sigma of the current measurement.

Using the 80.385 GeV PDG value of the W boson mass and assuming that the sum of squares of boson mass equals one half of the square of the Higgs vev implies a Higgs boson mass of 124.65 GeV as well, so the difference created by that assumption is too small to matter.

This suggests that the quantum corrections to the Higgs boson mass may indeed be very highly fine tuned making supersymmetry unnecessary to address that seemingly unlikely reality.

As discussed below, there is some tension between the best fit Higgs boson mass measurement and the best fit top quark measurement (under the assumption that the sum of the square of all fundamental particle masses equals to the square of the Higgs vev), with the Higgs boson measurement implying a higher than measured top quark measurement.  But, these tensions are within the margins of error in the measurements.  The latest combined best fit value of the top quark mass (i.e. 173.34 GeV) would imply a Higgs boson mass of 125.60 GeV, which is just outside the two sigma band of Higgs boson masses based upon the most recent measurement.

Implications for Top Quark Mass

This also significantly tightens the expected value of the top mass from the formula that the sum of the square of each of the fundamental particle masses equals the square of the Higgs vaccum expectation value.  The uncertainty in the Higgs boson mass had been the second greatest source of uncertainty in that calculation.  The best fit for the top quark mass on that basis (using a global fit value of 80.376 GeV for the W boson rather than the PDG value) is 173.73 GeV (173.39 to 174.07 GeV within the plus or minus one sigma band of the current Higgs boson measurement).  If the the sum of the square of the boson masses equals the sum of the square of the fermion masses the implied top quark mass is 174.03 GeV if pole masses of the quarks are used, and 174.05 GeV if MS masses at typical scales are used.

That compares to the latest top quark mass estimate from ATLAS of 172.99 +/- 0.91 GeV.  The latest combined mass estimate of the top quark (excluding the latest top quark mass measurement estimate from ATLAS) is 173.34 +/- 0.76 GeV.

How big are the gaps?

The fermion side of the balance sheet could fit a particle as massive as 19 GeV if the fermion sides and boson sides must be equal, and about 16 GeV if they need not be equal, consistent with current particle mass data alone.

But, particles in this mass range would greatly distort the expected cross-sections of Higgs boson decays in ways that would probably already be detectable.  Any such particle has been ruled out by W and Z boson decays to the extent that it can be produced by decays of these particles, and if they were present in Higgs boson decays would dramatically reduce, for example, the expected cross-section of bottom quark pairs from Higgs boson decays (which is the largest single cross-section from Higgs boson decays, making up about two-thirds of them, although this cross-section is hard to measure due to significant backgrounds that also produce bottom quark pairs).  Particles with masses of 10 MeV or less, in contrast, would have only a modest impact on the decay patterns observed in Higgs bosons decays, but would still have to be sterile as to W and Z boson interactions.

Another interesting possibility is that baryons could contribute to the fermion side, and that mesons could contribute to the boson side, rather than just the fundamental particles.  My intuition is that this would not work, but I haven't run the numbers.  Light baryons wouldn't add much, but the heaviest baryons with B quarks would make a significant contribution.  Still, order of magnitude, it isn't impossible.

Another issue is which masses we should be using: pole masses or masses at a single consistent mass scale.  Quark and lepton masses get slightly lower at higher energy scales.  The Higgs boson mass declines more rapidly with higher energy scales.  I think, but don't know, that the W and Z boson masses also decrease faster the quark and lepton masses at higher energy scales.

Since the top quark is the predominant contribution to the fermion side of the equation, only the decline from the top pole mass to some energy scale above the top pole mass is relevant.  But, since the fermion side is already "light" relative to the 50-50 expectation, any decline in the top mass hurts the balance (and would probably be less than 1% in addition to being less than the boson side reduction).  On the boson side, a reduction of 0.185% from the current best fit values would bring the sum of the square of the masses to one half of the Higgs vev.  This may understate the amount of actual renormalization reduction at plausible targets like the top quark mass and the Higgs vev.

The Higgs boson mass runs from 125 GeV at 125 GeV to zero at about 10^15 GeV, on a curve that is concave with respect to a log-linear relationship (i.e. masses are lower at every point except the end points relative to a log-linear relationship of Higgs boson mass and energy scale).  This seems to suggest that the Higgs boson mass at 246 GeV should be more than 13% lower than the pole mass (i.e. about 108.8 GeV), which is far too much of a reduction to fit the formula and would favor using pole masses across the board, as would the Higgs boson mass at 173.35 GeV which should be more than 11% lower than the pole mass of the Higgs boson, if I have the calculations right.  The 0.185% shift required would imply an energy scale of something less than 133.34 GeV (but more than 125.09 GeV), which doesn't make much sense under any theory.

Given how close the experimental masses are to the preferred values using pole masses, however, it isn't obvious that renormalized values are necessary.

But, if the apparent relationship does involve pole masses, then there is very little wiggle room indeed in the predicted values of the Higgs boson mass and top quark mass, although this can be relaxed a little if the sum of the square of the fundamental fermion masses need not be exactly equal to the sum of the square of the fundamental boson masses.

Did Dogs Drive The UP?

A new book entitled "The Invaders" by Pat Shipman, argues that the domestication of dogs was key to the Middle Paleolithic-Upper Paleolithic transition and to the demise of Neanderthals. The theory is reasonably plausible.

The Population Genetics Of The British Isles

A major new study of the whole genomes of the people of the British Isles has been published in the journal Nature.

A few of the "forest" level conclusions:

* The sample size is 2,039 people in the British Isles compared to 6,209 European individuals.  This is pretty much as big a sample as you get in historical population genetics.  The significance of these sample size is magnified by the fact that these are whole genomes, and not just Y-DNA or mtDNA haplogroup data.  Even very small samples of whole genomes can be highly informative, and these samples aren't small.

* All of the peoples of the British Isles are very homogeneous genetically, and the people of Central and Southern Britain (as well as Cornwall), are extremely homogeneous genetically.

This is particularly notable, given that Britain has more than four cultural/linguistic units that are recognized politically as different enough to require autonomy to some extent (Britain, Scotland, Wales, and Northern Ireland, plus some minor dependencies on nearby islands).

There is far more dialect variation in the British Isles than there is in the United States to the extent that one could make a very well informed estimate about someone's origins that is even finer grained than the genetic clusters within the British Isles identified by this study based upon that person's dialect and accent in the English language.

The British Isles are perhaps one of the clearest examples of strong cultural and linguistic substructure in a population that is genetically very homogeneous.  In most areas of the world, the kind of cultural and linguistic substructure seen in the British Isles corresponds to fairly dramatic population genetic differences between the various groups.  In the British Isles, in contrast, populations that are genetically almost identical and not all that far from each other geographically have very distinct cultural identities.

* The fine grained differences between British subpopulations correspond to influences from different parts of the Continental Europe and Scandinavia that largely correspond to population genetic events in the historic era and archaeologically well documented late prehistoric eras, more or less as one would expect with only minor surprises (like Cornwall that one might have expected to be more like  the Welsh people).

For example, as expected from our historical knowledge, the population genetics of Northern Ireland overlap heavily with the population genetics of the area around the western Scottish-English borderlands.

* The Danish Vikings who imposed Danelaw on Britain in the 1st millennium, while they had significant cultural and linguistic impact, had almost no genetic impact outside of the Orkney Islands.  This is analogous to the situation in Hungary, where the people who are the source of Hungary's current language have left almost no genetic trace in the country.

* The Anglo-Saxon contribution to the British gene pool in the 1st millennium is about 10% to 40% of the total (the spread is disappointingly large for such an impressive data set).  This is a significant minority contribution, but not population replacement.  This is reflected mostly in the Central-Southern British cluster that out of 17 clusters makes up about half of the total sample.  Many of the other clusters are in areas that have some level of political autonomy.  Wales, for example, appears to have five different small regional genetic clusters.

* The pre-Anglo-Saxon Celtic substrate in Britain was not uniform; it varied by region.

* There was substantial migration to Britain from Continental Europe in the Neolithic and later eras prior to the arrival of the Romans (and therefore also prior to the arrival of the Danes, the Anglo-Saxons, the Normans, and recent immigration from the 19th century onwards).

* I suspect, but don't know for a fact, that the sample was limited to people who are "ancestrally" British and hence excludes individuals with known recent immigrant ancestry.  Thus, Britain today is probably much more genetically diverse than this sample which was probably picked to be as informative as possible about the ancient and prehistoric genetic history of Britain would indicate.  For example, Britain has a significant South Asian minority population that is largest in greater London, but is found throughout the British Isles, that is not reflected in this data.  These huge genetic chasms, however, are not reflected in Britian's system of regional autonomy and instead is blended into preexisting communities across the British Isles.

Latest Top Quark Mass Measurement From ATLAS

The latest top quark mass measurement from ATLAS (at the LHC) is 172.99 +/- 0.91 GeV.

By comparison the PDG value is 173.21 +/- 0.87 GeV.

A somewhat more recent combined value (because it considers pre-prints and not just published papers) is 173.34 +/- 0.76 GeV.

An extended Koide's rule estimate of the top quark mass using only the electron and muon masses as inputs, predicted a top quark mass of 173.263947 ± 0.000006 GeV.

A prediction that I made in March 2014 which assumed a Higgs bosons mass of about 125.96 GeV and some other assumptions (some of which are just conjectures themselves), predicted a top quark mass of 173.1125 ± 0.0025 GeV.

Of course, the latest experimental value is consistent with all of the other values due to a lack of experimental precision in the top quark mass measurement, which is improving over time, but ever so slowly.

Has ATLAS Seen SUSY?

The ATLAS experiment at the LHC has reported a three sigma excess of events beyond the Standard Model expectation in a particular kind of search for squarks and gluinos, a type of particle predicted by Supersymmetry models.

This is one of the strongest experimental indicators of SUSY phenomena to date amidst an ocean of searches and may simply be an overstated statistical fluke due to look elsewhere effects (i.e. the notion that if you do enough searches, some will come up positive by random chance, undermining the significance of any particular result that is not replicated).  If CMS sees the same thing (and this study failed to reproduce a similar, but slightly weaker excess in the CMS data) then it could very well be real.  If CMS does not see it, it is probably just a fluke.

A five sigma effect is considered necessary to call a finding a "discovery" of a particle.

A summary at the conclusion of the paper states:

This paper presents results of two searches for supersymmetric particles in events with two same-flavour opposite-sign leptons, jets, and E miss T , using 20.3 fb−1 of 8 TeV pp collisions recorded by the ATLAS detector at the LHC. 

The first search targets events with a lepton pair with invariant mass consistent with that of the Z boson and hence probes models in which the lepton pair is produced from the decay Z → ``. In this search 6.4 ± 2.2 (4.2 ± 1.6) events from SM processes are expected in the µµ (ee) SR-Z, as predicted using almost exclusively data-driven methods. The background estimates for the major and most difficult-to-model backgrounds are cross-checked using MC simulation normalised in data control regions, providing further confidence in the SR prediction. Following this assessment of the expected background contribution to the SR the number of events in data is higher than anticipated, with 13 observed in SR-Z µµ and 16 in SR-Z ee. This corresponding significances are 1.7 standard deviations in the muon channel and 3.0 standard deviations in the electron channel. These results are interpreted in a supersymmetric model of general gauge mediation, and probe gluino masses up to 900 GeV. 

The second search targets events with a lepton pair with invariant mass inconsistent with Z boson decay, and probes models with the decay chain χ˜ 0 2 → ` + ` −χ˜ 0 1 . In this case the data are found to be consistent with the expected SM backgrounds. 

No evidence for an excess is observed in the region in which CMS reported a 2.6σ excess [24]. 

The results are interpreted in simplified models with squark- and gluino-pair production, and probe squark (gluino) masses up to about 780 (1170) GeV. 

Lubos Motl offers a cautious but hopeful assessment of the result being really due to SUSY.

UPDATED March 22, 2015: More SUSY exclusions here.

Prehistoric European Quick Hits

* The prehistoric record of tsunamis in Southwest Iberia helps to explain the archaeological record and suggests a possible Iberian tsunami as the source of the Atlantis myth.

* Maju notes the availability of a new collection of papers regarding the early Balkan Neolithic.  The was a launching pad from which much of the process of bringing farming and herding to Europe originated and in turn provides a way to discern its sources in turn.

* Bell Beaker blogger notes a polemic arguing that the Iberian expansion theory of Bell Beaker expansion isn't necessarily as strong, vis-a-vis a central European origin and dispersal in light of the archaeological evidence as has frequently been asserted.  The paper is thin on evidence, looking mostly to dates of Central European cemeteries without detailed discussion, and reinterpreting existing evidence, neither of which are powerful when going up against a prevailing paradigm in the field.  But, it does not mention evidence from the European Y-DNA R1b phylogeny that does tend to support a central European origin and makes the arguments there worth examining more closely.

* Bell Beaker blogger also continues to explore the links between ancient beer brewing and mystical or magic lore in prehistoric Europe, with a linguistic slant.

* Another intriguing Bell Beaker blogger post explores the potential roots of European pottery traditions in the far East and Jomon pottery traditions and links it to Y-DNA R expansion.

* And, Bell Beaker blogger also has a nice post on trade across the Strait of Gibraltar, before and after the Bell Beaker period, in goods like ivory and ostrich egg shells.

* Dienekes' Anthropology blog has picked up on a paper also discussed at Marginal Revolution (where I commented noting various adjustments that could be made to obtain a more accurate measurment) making back of napkin estimates of the potential genetic impact of capital punishment from 1500-1750 CE on the murder rate in Britain.  The murder rate fell tenfold in that period which also experienced many executions.

* Another paper notes at the same blog discusses the arrival of wheat in Britain thousands of years before farming commenced there.

* And, Dienekes comes to some conclusions from his own analysis of Armenian genetics.

* Scandinavian rock art suggests that ancient Swedes may have personally gone all the way to Cyprus to trade copper and tin for amber without a middle man in the Bronze Age.

* Eurogenes notes the important discovery of ancient Y-DNA R1a1 paired with mtDNA H in NW Russian towards Finland in hunter gatherer populations from ca. 4000 BCE.  This is one of several new ancient data points (another being the paper discussed here) that really reinforce the theory that Y-DNA R1a1 paired with mtDNA H in Europe arrived with Indo-Europeans from NW Russia as part of the Corded Ware culture in the Copper Age, and that R1b in Europe paired with mtDNA H might derive in the same period from further South around the Pontic-Caspian Steppe.  The autosomal data from the Pontic-Caspian steppe is a good fit for a major component (perhaps 75% replacement in Central Europe) of Europe's DNA.

* Eurogenes also discusses a new linguistics paper on a European steppe origin for the Indo-European languages.

Prospects For General Relativity A Century Later

Background

A hundred years ago, Albert Einstein came up with the theory of General Relativity that was first presented publicly at a conference in November of 1915, and was published early in 1916 in a series of three papers.

General Relativity basically describes gravity in a way that is subtly different from that of Newton's simply F=GMm/r² law of the 1600s that is perfectly sufficient for most purposes.  But, its formulations allow for a variety of phenomena that Newtonian gravity did not.

One of the most important distinctions is that energy, not just matter, generates and is subject to gravitational fields, and that energy is equivalent to matter for purposes of the conservation of matter-energy, and for gravitational purposes, according to the formula E=mc², where m is mass, E is energy, and c is the speed of light in a vacuum.  For example, since light has energy, it gravitates and is affected by gravity, giving rise to the phenomena of gravitational lensing.

Another critical distinction between General Relativity and Newtonian gravity arises in strong gravitational fields, where singularities such as Black Holes and the Big Bang can arise.  Both phenomena are observed.

There are other distinctions: frame dragging, gravitomagnetic effects, and more.  But, they are beyond the scope of this post.

One integration constant in Einstein's formulation of general relativity, known as the cosmological constant full describes to the limits of astronomy data such as the Planck satellite observations, a phenomena know today as "dark energy" when set to the appropriate value.

Einstein's insights come to us virtually unchanged in the leading textbook on the subject, "Gravitation", written by Charles W. Misner, Kip S. Thorne and John Archibald Wheeler in 1973 (called MTW by advanced physics students everywhere).

It is widely asserted that the behavior of a massless spin-2 boson that couple to Standard Model particles and itself with a strength equal in magnitude to the mass-energy of the particle, reproduces general relativity.  There is good reason to believe that this is wrong, and I discuss one of the reasons below.  But, I think that the spin-2 massless graviton model discussed in some of Feynmann's lectures, may be a more accurate description of gravity itself, than it is of General Relativity.

The Problem of Dark Matter Phenomena

But, neither General Relativity nor the Standard Model of Particle Physics, describe a set of phenomena known as "dark matter" which is necessary to model the cosmology of the universe from the Big Bang onward in a way that matches Planck data, and is also necessary to describe, for example, the disconnect between the observed rotation curves of galaxies which do not match the naive predictions of simplified versions of General Relativity applied to the observed luminous matter in those galaxies.

There are two ways to reconcile these effects to General Relativity and the Standard Model.

Dark Matter

One is to hypothesize the existence of "dark matter" that is massive, nearly collisionless with ordinary matter, made up of something other than the protons and neutrons that make up ordinary "baryonic" matter, and makes up the lion's share of matter in the universe.

The simplest model has just a single dark matter fermion particle, but many dark matter theories imagine the existence of dark forces that led to self-interaction of dark matter particles with each other by means other than gravity, or additional kinds of dark matter particles in a complex "dark sector" similar to that of the sector of ordinary matter described by the Standard Model.

At first it was hoped that this problem would be solved by Supersymmetry (SUSY) or string theory models, which would provide dark matter candidates.

Astronomers are no slouches and have worked hard on several fronts to infer the properties of the dark sector from observation.

One approach has been to use analytical and numerical models to determine what the universe should look like if it has a particularly kind and quantity of dark matter and then to compare the predictions of those models to what we actually observe.  The dark matter hypothesis, set forth vaguely, does a very good job of fitting observed cosmic background radiation patterns (which give rise to radio static among other things) to very precise observations, but have proved less successful at predicting the amount of structure observed in the universe (e.g. how many dwarf galaxies surround the Milky Way galaxy and other galaxies of similar size) and halo distribution shape.

One approach has been to infer the distribution and mass of dark matter halos around galaxies from their rotation curves and known luminous matter.  Similar inferences have been made in systems like the Bullet Cluster where a colliding galaxy provides a means by which to discriminate between theories, an in examinations of RAVE stars in the Milky Way galaxy that are outside the galactic plane.  We have some idea regarding what shape dark matter halos must have to fit observations.  Unfortunately, the shape of the halos observed are not a great fit to the NFW dark matter halo shapes we would expect from analytical simulations to see if they universe were made entirely of a single kind of "cold" (i.e. GeV to TeV mass) dark matter particles.  Simulations match experiment between when gravitational interactions between baryons and dark matter are considered, but still show far more scatter in dark halo shapes than is observed.  Simulations also tend to favor "warm dark matter" (in the keV particle mass range) over "cold dark matter" in the GeV to TeV particle mass range that lack self-interactions.

A third approach has been to try to directly detect dark matter particles at high energy colliders.  This has not revealed any evidence of dark matter.  But, they have made clear that dark matter must be made up of one or more types of particles not found in the Standard Model, if it exists, and these effects strongly constrain the parameter space of potential dark matter particles.

A fourth approach has been to in build direct dark matter detection experiments.  So far, these have not revealed any convincing evidence of dark matter.  There have been a few potential "hits" but those have been contradicted by more accurate measurements, or confirmed by experiments of similar accuracy.

A fifth approach has been to look at cosmic rays to see if any could be produced by a hypothetical dark matter annihilation interaction and have no other known source.  Several candidates have been identified as potential signals of dark matter by these means, although there is not a consensus on how to interpret this data.

Modifications of Gravity

The other is to tweak General Relativity in weak gravitational fields of large objects such as galaxy and galactic clusters, in a way that reproduces phenomena attributed to dark matter.  There are about half a dozen to a dozen ways of doing this in a way that reproduces the dark matter phenomena seen in galaxies with a fair degree of accuracy that have been published and compared to the data, the most famous of which is MOND, a toy model theory proposed in 1983 by Mordehai (Moti) Milgrom.

MOND itself is not the best of those theories.  It is strictly a phenomenological relationship, it underestimates dark matter effects in galactic clusters, and it isn't great at predicting galactic dynamics outside the plane of a galaxy.  But, it also has an impressive record of making firm predictions about unobserved phenomena that were later confirmed by observation, with only one new experimentally measured physical constant, and has a general relativistic generalization, TeVeS, devised by one of Milgrom's colleagues, Jacob D. Bekenstein.

MOG and similar theories proposed by John M. Moffat as the University of Toronto, has the distinction of having a broader range of applicability that describes phenomena in galactic clusters as well as galaxies.

A number of theories known as F(R) theories, which add a term that is a function of the Ricci scalar to the equations of general relativity, have also had some success in describing dark matter, dark energy and cosmological inflation.

If General Relativity Is Wrong, In What Way Is It Wrong?

General Relativity is a very tightly formulated set of equations based on a handful of mathematical first principles.  But, perhaps quantum gravity or simply an omitted term in General Relativity could do what modified gravity theories that account for dark matter do.

To go beyond purely phenomenological models like MOND to a full fledged competitor to General Relativity, however, one needs a good theoretical justification for the modifications to the equations of General Relativity.

Deur has been at the forefront of demonstrating that the real key problem could be that conventional general relativity theory is wrong about the real world effects of gravitational self-interactions.

Section 20.4 of MTW at 467 is emphatic about this question:

To ask for the amount of electromagnetic energy and momen tum in an element of 3-volume make sense.  First, there is one and only one forula for this quantity.  Second, and more important, this energy-momentum in principle "has weight."  It curves space.  It serves as a source term on the righthand side of Einstein's field equations.  It produces a relative geodesic deviation of two nearby world lines that pass through the region of space in question.  It is observable.  Not one of these properties does "local gravitational energy-momentum" possess.  There is no unique formula for it, but a multitude of quite distinct formulas.  The two cited are only two among an infinity.  Moreover, "local gravitational energy-momentum" has no weight.  It does not curve space.  It does not serve as a source term on the righthand side of Einstein's equations.  It does not produce any relative geodesic deviation of two nearby world lines that pass through the region of space in question.  It is not observable. 

Anybody who looks for a magic formula for "local gravitational energy-momentum" is looking forthe right answer to the wrong question.  unhappily, enormous time and effort were devoted in the past to trying to "answer this question" before investigators realized the futility of the enterprise.  Toward the end, above all mathematical arguments, one came to appreciate the quiet but rock-like strength of Einstein's equivalence principle.  One can always find in any given locality a frame of reference in which all local gravitational fields" (all Christoffel symbols . . .) disappear.  No [Christoffel symbols] means no "gravitational field" and no local gravitational field means no "local gravitational energy-momentum." 

Nobody can deny or wants to deny that gravitational forces make a contribution to the mass-energy of a gravitationally interacting system.  The mass-energy of the Earth-moon system is less than the mass-energy that system would have if the two objects were at infinite separation.  The mass-energy of a neutron star is less than the mass-energy of the same number of baryons at infinite separation.  Surround a region of empty space where there is a concentration of gravitational waves, there is a net attraction, betokening a positive net mass-energy in that region of space (see Chapter 35).  At issue is not the existence of gravitational energy, but the localizability of gravitational energy.  It is not localizable.  The equivalence principle forbids it.

Of course, in 1915, and even in 1973, the analogy of QCD, in which a force is carried by particles that are self-interacting (gluons in that case) was not known.  But, QCD without self-interacting gluons would produce a very different effect.

A graviton, of course, is the very epitome of localized gravitational energy, which is why conventional General Relativity as espoused in MTW is fundamentally inconsistent with quantum gravity theories.

Deur argues, by analogy to QCD, that self-interacting gravitons do indeed have observable effects and gravitons curve space just like any other carrier boson would.  To the extent that Einstein's equations do not reflect this fact, they are wrong.  This, he argues with back of napkin estimates, produces dark matter phenomena of approximately the right amount in galaxies and galactic clusters, and accurately reflects the pattern seen in which more spherically symmetric systems have less apparent dark matter than those that have (in the original sense of the word) more pretzelosity.

Gravity is weak, and so, the gravitational self-interactions of gravity in low mass systems are modest.  but, gravity is also cumulative, because it is always attractive, so in immense systems, gravitational self-interactions have material observable effects that probably give rise to substantially all dark matter phenomena, and by weakening gravitational fields in directions from which gravitons are diverted to give rise to dark matter phenomena effects elsewhere, also some or all dark energy phenomena.

Future Prospects

I am quite convinced that the failure of the Einstein equations to reflect a contribution of gravitational self-energy is the most likely by far reason for dark matter phenomena that we observe and most of the dark energy phenomena that we observe, and that correcting this error will cause theory and observation to match exquisitely without the need for any beyond the Standard Model particles other than the massless spin-2 graviton that couples with a strength equal to the mass-energy of a particle.

I am confident that sooner or later, probably within ten to forty years, such a theory will be well articulated and tested against the data and will become the scientific consensus, and that dark matter theories will be discarded.

Thus, we will be left with the Standard Model and a very simple quantum gravity, with no dark matter or dark energy.  Thus, the six quarks, three charged leptons, three neutrinos, photon, three weak force bosons, eight gluons and Higgs boson of the Standard Model, plus the graviton and their interactions according to four coupling constants, will prove to be the only particles needed to account for everything in the universe.  All other proposed theories of fundamental physics will end up on the scrap heap of intellectual history.  Maybe somebody will come up with a way to unify these pieces and explain the source of all of their constants, and maybe they won't.  But, for practical purposes, it doesn't really matter one way or the other.  The results will be the same.

Trying 23andMe

I have ordered 23andMe personal genome kits for the whole family.  The price is right and the technology seems to be mature for the near future.  Honestly, as much as anything, the reason for doing so is not to learn anything new about my ancestry as it is to confirm my confidence in the testing system.

I know a great deal more about my ancestry than most people.  I've met numerous third and fourth cousins, have met relatives from Finland (whom my parents and brother visited in person), and I am familiar with the time and exact place from which my German ancestors emigrated (my father was finally able to meet some of my relatives there when West Germany and East Germany merged), and I have a fair amount of familiarity with my Irish ancestors (although no one in my family has made contact with my Irish relations).

We also know quite a bit about my wife's Korean ancestors and could probably trace their ancestry for hundreds of years with a visit to Korea if I spoke Korean and the relevant records weren't destroyed or placed beyond reach in North Korea during the Korean War.

We've been close enough to family that we also have a reasonably complete medical history, and genetics is still enough in its infancy that even if 23andMe were allowed to make medical commentary of the raw genome data (for the foreseeable future it is prohibited by the FDA from doing that), the predictions from our medical history would probably be more accurate.

We also know at least some of our relatives are in the system and might pop up as related.  And, of course, we have actual phenotype knowledge about ourselves that can be matched against those genes for which phenotype-genotype relationships have been established (e.g. eye and hair and skin pigmentation, ear wax type, etc.).

Still, it will be fun to see the results, and to see the strong predictions that I can make about them fulfilled (or contradicted) in detail.

Neutrino Physics Update

The 16th Neutrino Telescope Conference is underway.

One notable early result puts the sum of the three neutrino masses between the 0.056 eV lower bound from oscillation experiments, and an upper bound of 0.14 eV at a 95% confidence interval.  This is almost, but not quite, tight enough to distinguish between a "normal" and an "inverted" neutrino mass hierarchy.  This means that the absolute masses of the neutrinos are now known with a precision rivaling that of the up quark.

State of the art direct measurements of absolute neutrino masses which are in the process of being carried out would place only a 0.4 eV cap on the mass of the electron neutrino, which we know from cosmology must actually be less than about 0.05 eV, and in a normal hierarchy is likely to be about 0.001 eV or less.

UPDATED March 5, 2015:

The lastest neutrinoless double beta decay exclusion from GERDA at a 90% confidence interval is now a low limit on the half-life of neutrinoless double beta decay of 2.1*10^25 years.  This is unchanged since last summer.

God, Country, Yale or . . .

I would lay down my life for two brothers or eight cousins.

- J.B.S. Haldane, from here.

A Theoretical Case For The Higgs Boson As A Composite Particle Made Of Gauge Bosons

The case for the Higgs boson as a scalar combination of electroweak gauge bosons in a gauge invariant fashion is made in a preprint by F.J. Himpsel (of the University of Wisconsin at Madison Physics Department who primarily works in condensed matter physics; another of his interesting ideas about fundamental physics and additional explanation of the one described in the preprint is found here). The preprint makes a theoretical case for a Higgs boson as a composite object made of gauge bosons whose mass is half of the Higgs vacuum expectation value (vev) at the tree level before adjustment for higher order loops that bridge the gap between the tree level estimate and the experimentally observed value.

The paper is notable because it takes these related notions from being mere numerology, to something with some plausible theoretical foundation and can close the gaps between rough first order theoretical estimates and reality in a precise, calculable, falsifiable way.  There is a lot of suggestive evidence that he is barking up the right tree.  And, there is much to like about the idea of a Higgs boson as a composite of the Standard Model gauge bosons as discussed in the final section of this post.

The preprint discusses that the Higgs boson mass is close to half of the Higgs vev, 123 GeV (actually closer to 123.11 GeV), a 2% difference.  This gap is material, on the order of a five sigma difference from the experimentally measured value, but the explanation for the discrepancy is interesting and plausible (some mathematical symbols translated into words):

The resulting value MH = ½v = 123 GeV matches the observed Higgs mass of 126 GeV to about 2%. A comparable agreement exists between the tree-level mass of the W gauge boson MW = ½gv = 78.9 GeV in (8) and its observed mass of 80.4 GeV. Such an accuracy is typical of the tree-level approximation, which neglects loop corrections of the order the weak force coupling constant = g^2/4pi which is approximately equal to 3%. It is reassuring to see the Higgs mass emerging directly from the concept of a Higgs boson composed of gauge bosons.

The summary at the end of the paper notes that:

In summary, a new concept is proposed for electroweak symmetry breaking, where the Higgs boson is identified with a scalar combination of gauge bosons in gauge invariant fashion. That explains the mass of the Higgs boson with 2% accuracy. In order to replace the standard Higgs scalar, the Brout-Englert-Higgs mechanism of symmetry breaking is generalized from scalars to vectors. The ad-hoc Higgs potential of the standard model is replaced by self-interactions of the SU(2) gauge bosons which can be calculated without adjustable parameters. This leads to finite VEVs of the transverse gauge bosons, which in turn generate gauge boson masses and self-interactions. Since gauge bosons and their interactions are connected directly to the symmetry group of a theory via the adjoint representation and gauge-invariant derivatives, the proposed mechanism of dynamical symmetry breaking is applicable to any non-abelian gauge theory, including grand unified theories and supersymmetry.

In order to test this model, the gauge boson self-interactions need to be worked out. These are the self-energies [of the W+/- and Z bosons] and the four-fold vertex corrections [of the WW,WZ, and ZZ boson combinations]. The VEV of the standard Higgs boson which generates masses for the gauge bosons and for the Higgs itself is now replaced by the VEVs acquired by the W+/- and Z gauge bosons via dynamical symmetry breaking. Since the standard Higgs boson interacts with most of the fundamental particles, its replacement implies rewriting a large portion of the standard model. Approximate results may be obtained by calculating gauge boson self-interactions within the standard model, assuming that the contribution of the standard Higgs boson is small for low-energy phenomena. The upcoming high-energy run of the LHC offers a great opportunity to test the characteristic couplings of the composite Higgs boson, as well as the new gauge boson couplings introduced by their VEVs. If confirmed, the concept of a Higgs boson composed of gauge bosons would open the door to escape the confine of the standard model and calculate previously inaccessible masses and couplings, such as the Higgs mass and its couplings.

Background: The Standard Model Constants

The combined margin of error weighted experimental value of the Higgs boson mass as of the latest updated results from the LHC in September of 2014 is 125.17 GeV with a one sigma margin of error in the vicinity of about 0.3 GeV-0.5 GeV.  In other words, there is at least a 95% probability that the true Higgs boson mass is between 124.17 GeV and 126.17 GeV, and the 95% probability range is probably closer to 124.37 GeV and 125.97 GeV.

The experimentally measured value of the Higgs vev is 246.2279579 +/- 0.0000010 GeV. Conceptually, this is a function of the SU(2) electroweak force coupling constant g and the W boson mass.  In practice, it is determined using precision measurements of muon decays.

The other fundamental particle masses in the Standard Model are as follows:

* The top quark mass is 173.34 +/- 0.76 GeV (determined based upon the data from the CDF and D0 experiments at the now closed Tevatron collider and the ATLAS And CMS experiments at the Large Hadron Collider as of March 20, 2014).
* The bottom quark mass is 4.18 +/- 0.03 GeV (per the Particle Data Group).  A recent QCD study has claimed, however, that the bottom quark mass is actually 4.169 +/- 0.008 GeV.
* The charm quark mass is 1.275 +/- 0.025 GeV (per the Particle Data Group).  A recent QCD study has claimed, however, that the charm quark mass is actually 1.273 +/- 0.006 GeV.
* The strange quark mass is 0.095 +/- 0.005 GeV (per the Particle Data Group).
* The up quark mass and down quark mass, are each less than 0.01 GeV with more than 95% confidence, although the up quark mass and down quark pole masses are ill defined and instead are usually reported at an energy scale of 2 GeV.
* The tau charged lepton mass is 1.77682 +/- 0.00016 GeV (per the Particle Data Group).
* The muon mass is 0.1056583715 +/- 0.0000000035 GeV (per the Particle Data Group).
* The electron mass is 0.000510998928 +/- 0.000000000011 GeV (per the Particle Data Group).
* Each of the three Standard Model neutrino mass eigenstates (regardless of the neutrino mass hierarchy that proves to be correct) is less than 0.000000001 GeV.
* The W boson mass is 80.365 +/- 0.015 GeV.
* The Z boson mass is 91.1876 +/- 0.021 GeV.
* Photons and gluons have an exactly zero rest mass (as does the hypothetical graviton).

The only other experimentally determined Standard Model constants not set forth above are:

* The strong force coupling constant (about 0.1185 +/- 0.0006 at the Z boson mass energy scale per the Particle Data Group).
* The U(1) electroweak coupling constant g', which is known with exquisite precision.  I believe that the value of g is about 0.65293 and that the value of g' is about 0.34969 (both of which are known with much greater precision).
* The four parameters of the CKM matrix, which are known with considerable precision.  In the Wolfenstein parameterization, they are λ = 0.22537 ± 0.00061 , A = 0.814+0.023 −0.024, ρ¯ = 0.117 ± 0.021 , η¯ = 0.353 ± 0.013.
* The four parameters of the PMNS matrix; three of which are known with moderate accuracy.  These three parameters are theta12=33.36 +0.81/-0.78 degrees, theta23=40.0+2.1/-1/5 degrees or 50.4+1.3/-1.3 degrees, and theta12=8.66+0,44/-0.46 degrees.

None of these are pertinent to the issues discussed in this post. All of these except the CP violating phase of the PMNS matrix and the quadrant of one of the PMNS matrix parameters has been measured with reasonable precision.

General relativity involves two constants (Newton's constant which is 6.67384(80)×10⁻¹¹ m³*kg⁻¹*s⁻² and the cosmological constant which is approximately 10^-52 m^-2).

In addition, Planck's constant (6.62606957(29)×10⁻³⁴ J*s) and the speed of light (299792458 m*s⁻¹) are experimentally measured constants (even though the speed of light's value is now part of the definition of the meter), that are known with great precision and which must be known to do fundamental physics in the Standard Model and/or General Relativity.

A small number of additional experimentally determined constants may be necessary to describe dark matter phenomena and cosmological inflation.

A Higgs Boson Mass Numerology Recap

The intermediate equations in the tree-level analysis in the paper suggests how the 125.98 +/- 0.03 GeV/c^2 value that the simple 2H=2W+Z formula suggests could be close to the actual result.  If this similar formula were true, the combined electroweak fits of the W boson mass, top quark mass and Higgs boson mass favor a value at the low end of that range, perhaps 125.95 GeV/c^2.

* * *

An alternative possibility, in which one half of the Higgs boson mass equals exactly the sum of the squares of the massive fundamental bosons of the Standard Model (and the sum of the squares of the masses of the fundamental fermions has the same value as the sum of the squares of the boson masses), i.e., for Higgs vev=V, Higgs boson mass=H, W boson mass=W, and Z boson mass=Z:

H^2=(V^2)/2-W^2-Z^2, implies a Higgs boson mass of 124.648 +/- 0.010 GeV, with combined combined electroweak fits favoring a value at the high end of this range (perhaps 124.658 GeV).  (This would imply a top quark mass of about 174.1 GeV which is consistent with the current best estimates of the top quark mass; a slightly lower top quark mass of 173.1 GeV would be implied if the Higgs boson mass were, for instance, 125.95 GeV; both of these top quark masses are within 1 standard deviation of the experimentally measured value of the top quark mass).

This could also have roots in the analysis in the paper, which includes half of the square of the Higgs vev, the W boson mass, and the Z boson mass in its analysis (and has terms for the photon mass that drop out because the photon has a zero mass).

* * *

Thus, both alternative possibilities (2H=2W+Z and sum of F^2= sum of B^2= 1/2 Higgs vev) are roughly consistent with the experimental evidence, although they are clearly inconsistent with each other using pole masses for each boson.

It is also possible, however, that the correct scale at which to evaluate the masses in these formulas might, for example, be closer to the Higgs vev energy scale of about 246 GeV, and that at that scale, both formulas might be true simultaneously.  Renormalization of masses as energy scales increase shrink the fundamental gauge boson masses more rapidly than they shrink the fundamental fermion masses, and an energy scale at which the sums of the squares of the fermion masses equal the sum of the squares of the boson masses is less than 1,000 GeV (i.e. 1 TeV) and not less than the value determined using the pole masses of the respective fundamental particles.

In a naive calculation using the best known values of the fundamental fermion and boson masses, the sum of the square of the fermion masses are not quite equal to the sum of the square of the boson masses (including the Higgs boson mass).  But, the uncertainties in the top quark mass, the Higgs boson mass, and the W boson mass (in that order) are sufficient to make it unclear how the sum of the square of the fermion masses relate to the sum of the square of the boson masses either at pole masses or at any other energy scale.  The uncertainties in these three squared masses, predominate over any uncertainties in the masses of the other 11 fermions, the Z boson (whose mass is known with seven times more precision than the W boson despite having a higher absolute value), and uncertainty in the value of the Higgs vev.

If these top quark and Higgs boson mass measurements could be made about three times more precise than the current state of the art experimental measurments, most of the current uncertainty regarding the nature of the Higgs boson mass and the relationship of the fundamental particle masses to the Higgs vev could be eliminated.  The remainder of the LHC experiments will almost surely improve the accuracy of both of these measurements, but may be hard pressed to improve them by that much before these experiments are completed.

What Does A Composite Higgs Boson Hypothesis Imply?

It is always a plus to be able to derive any experimentally determined Standard Model parameter from other Standard Model parameters, reducing the number of degrees of freedom in the theory.  This would make electroweak unification even more elegant.

More deeply, if the Higgs boson is merely a composite of the Standard Model electroweak gauge bosons, then:

(1) The hierarchy problem as conventionally posed evaporates, because the Higgs boson mass itself is no longer fine tuned.  The profound fine tuning of the Higgs boson mass in the Standard Model is the gist of the hierarchy problem.  The demise of the hierarchy problem removes an important motivation for SUSY theories.

(2) Some of the issues associated with the hierarchy problem migrate to the question of why the W and Z boson mass scales are what they are, but if the Higgs boson mass works out to be such that the fermionic and bosonic contributions to the Higgs vev are identical, then the W and Z boson masses are a function of the fermion masses and an electroweak mixing angle, or equivalently, the fermion masses are a function of the electroweak boson masses and the texture of the fermion mass matrix.

(3) The spotlight in the mystery of the nature of the fermion mass matrix would cease to be arbitrary coupling constants with the Higgs boson and return squarely to W boson interactions which are the only means in the Standard Model by which fermions of one flavor can transform into fermions of another flavor.

(4) There are no longer any fundamental Standard Model bosons that are not spin-1 (the hypothetical spin-2 graviton is not part of the Standard Model).  All fundamental Standard Model fermions are spin-1/2.  Eliminating a fundamental spin-0 boson from the Standard Model changes the Lie groups and Lie algebras which can generate the Standard Model fundamental particles without excessive or missing particles in a grand unified theory.

(5) If the Higgs boson couplings are derivative of the W and Z boson couplings, then neutrinos, which couple with the W and Z boson, although only via the weak force, should derive their masses via the composite Higgs boson mechanism, just as other fermions in the Standard Model do.  This implies that neutrinos should have Dirac mass just like other particles that derive their masses from the same interactions.

(6) A composite Higgs boson makes models with additional Higgs doublets less plausible, except to the extent that different combinations of fundamental Standard Model gauge bosons can generate these exotic Higgs bosons, which if they can, would then have masses and other properties that could be determined from first principles and would be divorced from supersymmetry theories.

(7) A composite Higgs boson might slightly tweak the running of the Standard Model coupling constants, influencing gauge unification at high energies (as could quantum gravity effects).  A slight tweak of 1-2% to the running of one or more of the coupling constants over from the electroweak scale to the Planck or GUT scale (more than a dozen orders of magnitude), is all that would be necessary for the Standard Model coupling constants to unify at some extremely high energy.  It may also have implications for the unstable v. metastable v. stable nature of the vacuum.

The Proca Model and Podolsky Generalized Electrodynamics

Background and Motivation 

The Standard Model, and in particular, the quantum electrodynamics (QED) component of the Standard Model, assumes that the photon does not have mass (although photons do, of course, have energy, and hence are subject to gravity in general relativity in which gravity acts upon both matter and energy).

Now, almost nobody seriously thinks that the assumption of QED that the photon is massless is wrong, because the predictions of QED are more precise, and are indeed more precisely experimentally tested than any other part of the Standard Model, or for that matter almost anything in experimental physics whatsoever.  There is no meaningful experimental or theoretical impetus to make the assumption that the photon is massless.

But, generalizations of Standard Model physics that parameterize deviations from the Standard Model expectation, provide a useful tool for devising experimental tests to confirm or contradict the Standard Model and to quantify how much deviation from the Standard Model has been experimentally excluded.

Also, any time one can demonstrate that it is possible to have a new kind of force with a massive carrier boson that behaves in a manner very much like QED, but not exactly like QED, that is theoretically rigorous, these theories, once their implications are understood, can be considered as possible explanations for explaining unsolved problems in physics.

For example, many investigators have considered a massive "dark photon" as a means by which dark matter fermions could be self-interacting very similar to the models discussed below, because self-interacting dark matter models seem to be better at reproducing the dark matter phenomena that astronomers observe, than dark matter models in which dark matter fermions interact solely via gravity and Fermi contact forces (i.e. the physical effects of the fact that two fermions can't be in the same place at the same time) with other particles and with each other.

The Proca Model and Podolsky Generalized Electrodynamics

A paper published in 2011 and just posted to arVix today for some reason evaluates the experimental limitations on this assumption.

The Proca model of Romanian physicist Alexandru Proca (who became a naturalized French citizen later in life when he married a French woman) was developed on the eve of World War II, mostly from 1936-1938 considers a modification of QED in which the photon has a tiny, but non-zero mass. Proca's equations still have utility because they describe the motion of vector mesons and the weak force bosons, both of which are massive spin-1 particles that operate only at short ranges as a result of their mass and short mean lifetimes.

Experimental evidence excludes the possibility that photons have Proca mass (according to the 2011 paper linked above and cited below) down to masses of about 10^-39 grams (which is roughly equivalent to 10^-6 eV/c²). This is on the order of 10,000 lighter than the average of the three neutrino masses (an average which varies by about a factor of ten between normal, inverted and degenerate mass hierarchies). The exclusion (assuming that no mass is discovered) would be about 100 times more stringent if an experiment proposed in 2007 is carried out. This exclusion for Proca mass is roughly equal to the energy of a photon with a 3 GHz frequency (the frequency of UHF electromagnetic waves used to broadcast television transmissions); visible light has more energy and a roughly 300 THz frequency (10,000 times more energetic).

The Particle Data Group's best estimate of the maximum mass of the photon is much smaller than the limit cited in the 2011 article, with a mass of less than 10^-18 eV/c² from a 2007 paper (twelve orders of magnitude more strict). A 2006 study cited by not relied upon by PDG claimed a limit ten times as strong.  A footnote at the PDG entry based on some other 2007 papers notes that a much stronger limit can be imposed if a photon acquires mass at all scales by a means other than the Higgs mechanism (with formatting conventions for small numbers adjusted to be consistent with this post):

When trying to measure m one must distinguish between measurements performed on large and small scales. If the photon acquires mass by the Higgs mechanism, the large-scale behavior of the photon might be effectively Maxwellian. If, on the other hand, one postulates the Proca regime for all scales, the very existence of the galactic field implies m < 10^-26 eV/c², as correctly calculated by YAMAGUCHI 1959 and CHIBISOV 1976.

Ordinarily a massive photon would break the gauge symmetry of QED, which would be inconsistent with all sorts of experimentally confirmed theoretical predictions that rely upon the fact that the gauge symmetry of QED is unbroken.

But, it is possible to find a loophole in the assumption that a massless photon would break the gauge symmetry of QED.  Specifically, the Podolsky Generalized Electrodynamics model, proposed in the 1940s by Podolsky, incorporates a massive photon in a manner that does not break gauge symmetry. In this model, the photon has both a massless and massive mode, with the former interpreted as a photon and the later tentatively associated with the neutrino by the Podolsky when the model was formulated (an interpretation that has since been abandoned for a variety of reasons). In the Podolsky Generalized Electrodynamics model, Coulomb's inverse square law describing the electric force of a point charge is slightly modified. Podolosky Generalized Electrodynamics is equivalent to QED in the limit as Podolsky's constant "a" approaches zero.

Podolosky Generalized Electrodynamics is also notable because it can be derived as an alternative solution to one that uses a set of very basic assumptions to derive Maxwell's Equations from first principles, and does so in a manner that prevents the infinities found in QED because it has a point source (which Feynman and others solved for practical purposes with the technique of renormalization) from arising.

In the Podolsky Generalized Electrodynamics model, there is a constant "a" with units of length associated with the massive mode of the photon must have a value that is experimentally required to be smaller than the current sensitivity of any current experiments.  But, "a" is required as a consequence of the "value of the ground state energy of the Hydrogen atom . . . to be smaller than 5.6 fm, or in energy scales larger than 35.51 MeV."

In practice (for reasons that are not obvious without reading the full paper), this means that deviations from QED due to a non-zero value of "a" could be observed only at high energy particle accelerators.

It isn't inconceivable, however, to imagine that Podolsky's constant had a value on the order of the Planck length (i.e. 1.6 * 10^-35 meters), which would be manifest only at energies approaching the Planck energy which is far beyond the capacity of any man made experiment to create, a value which could be correct without violating any current experimental constraints that have been rigorously analyzed to date.

Selected References

* B. Podolsky, 62 Phys. Rev. 68 (1942).
* B. Podolsky, C. Kikuchi, 65 Phys. Rev. 228 (1944).
* B. Podolsky, P. Schwed, 20 Rev. Mod. Phys. 40 (1948).
* R. R. Cuzinatto, C. A. M. de Melo, L. G. Medeiros, P. J. Pompeia, "How can one probe Podolsky Electrodynamics?", 26 International Journal of Modern Physics A 3641-3651 (2011) (arVix preprint linked to in post).

Occam's Razor v. Clinton's Rule In Physics

[T]he A particle is one of the five physical states arising in the Higgs boson sector if you admit to add to the Standard Model Lagrangian density two doublets of complex scalar fields instead than just one.

Why should we be such perverts ? I.e., if the theory works fine with fewer parameters, why adding more? Well: the answer is the same as that given by Clinton when he was asked why he seduced an intern... Because we could.

From Quantum Diaries Survivor (emphasis in the original) discussing the paper previously blogged here in this post (note that the physicist author's first language is Italian, not English).

In other physics news, a new paper sketches out the main current issues of active investigation in QCD. 

And, a new analysis determines that the latest potential signs of SUSY at the LHC aren't.  A new CMS study of a quite generalized class of high energy proton-proton collisions with missing traverse energy, an opposite sign lepton pair, and jets, likewise fails to detect hints of SUSY and sets new SUSY limits (e,g., excluding gluino masses of less than about 900 GeV for neutralinos of under 200 GeV, excluding gluino masses up to 1100 GeV for neutralino masses of up to about 800 GeV, and excluding bottom squark masses of 250 GeV-350 GeV and 450 GeV to 650 GeV subject to various assumptions).

True Statements About Fundamental Physics

Mouse over:

"Of these four forces, there's one we don't fully understand."
"Is it the weak force or the strong --"
"It's gravity."

------------------

Seriously, a hundred years after Einstein published his paper on General Relativity, this is still the most problematic of the fundamental forces.  The strong force (QCD) is still hard to calculate, but we think we understand it at a fundamental level.

Grain As Prehistory

[This is another draft post from the year 2010 that is resurrected without major further research.  It too was never posted because of its original, overambitious scope that has been abandoned in this post.]

Although corn was domesticated only 8,000 to 10,000 years ago from the grass teosinte, the genetic diversity between any two strains of corn exceeds that found between humans and chimpanzees, species separated by millions of years of evolution. For instance, the strain B73, the agriculturally important and commonly studied variety decoded by the maize genome project, contains 2.3 billion bases, the chemical units that make up DNA. But the genome of a strain of popcorn decoded by researchers in Mexico is 22 percent smaller than B73’s genome.

“You could fit a whole rice genome in the difference between those two strains of corn,” says Virginia Walbot, a molecular biologist at Stanford University.

From here.

Mostly, this is a sideshow. Different kinds of wheat (which comes in duploid to hexaploid varieties, with the hexaploid monster genome found in the most commonly consumed varieties) for example, also shows great genetic diversity as measured by numbers of bases, but some of this is a product of how you choose to measure genetic diversity, because the variations aren't simply random mutations.

In fact, other recent research on grain genetics shows that just a handful a key, independent, simple mutations account for the traits that led to the practical differences between the wild plants that were the marginally nourishing ancestors of the world's staple grains (e.g., rice, maize a.ka. corn, and wheat) and the contemporary domesticated varieties that feed the world.

Far more interesting to me is the extent to which a genetic analysis of foods and domesticated animals makes it possible to localize the epicenters of the Neolithic revolution and date the times when the domestication occurred. Modern humans (i.e. post-Neanderthals) transitioned from many tens of thousands of years as a hunter-gatherer society to a farming society at something like a dozen independent locations around the world at roughly the same time give or take a few thousand years. Each location domesticated different plants and animals.

Seeds from domesticated plants can often be recognized on sight, survive thousands of years better than dead animal matter, and can be carbon dated.

Comparisons of the genomes of domesticated plants and animals to wild species usually makes it possible to make a very specific identification of a common wild ancestor, often an ancestors with a quite narrow geographic range. For example, genetic evidence provides strong support for the notion that all maize has a single common domesticated ancestor about 9,000 years ago in a fairly specific highlands part of Southern Mexico.

Similarly, the story of wheat is also a high definition bit of genetic history.

Einkorn wheat was one of the earliest cultivated forms of wheat, alongside emmer wheat (T. dicoccon). Grains of wild einkorn have been found in Epi-Paleolithic sites of the Fertile Crescent. It was first domesticated approximately 9000 BP (9000 BP ≈ 7050 BCE), in the Pre-Pottery Neolithic A or B periods. Evidence from DNA finger-printing suggests einkorn was domesticated near Karacadag in southeast Turkey, an area in which a number of PPNB farming villages have been found.

The origins of maize and wheat are known in time to a period of plus or minus a few hundred years, and in place to regions the size of a few contiguous counties. We can trace the origins of the greater Mexican squash-maize-bean triad of staples to the separate but adjacent areas, resolve order they were developed in (squash came first), and determine how quickly this pattern of domestication spread from carbon dated archeological evidence.

The Hittites

[The following post is extracted from a post written on April 14, 2010, but got lost in the shuffle in my drafts folder when its overambitious original scope got out of hand.  I am posting it now, retroactively, without modification to reflect new information, so that the sources and facts noted at the time are available for reference purposes.  Further edited for style and grammar on February 18, 2015.]

The Pre-Hittites

The capitol of the Hittite empire, where the first documents written in an Indo-European language are found, was Hattusa. Archaeological evidence shows that it was founded sometime between 5000 BCE and 6000 BCE, and Hittite history records the fact that it and the city of Nerik to the North of it, were founded by the non-Indo-European language speaking Hattic people who preceded them.

Both Hattsua and Nerik had been founded by speakers of the non-Indo-European, non-Semitic language called Hattic. Hattic shows similarities to both Northwest (e.g., Abkhaz) and South Caucasian (Kartvelian) languages, and was spoken sometime around the 3rd to 2nd milleniums BCE. The pre-Indo-European language spoken in Eastern Anatolia and the Zargov mountains, which also shows similarities to the languages of the Caucuses was Hurrian.

"Sacred and magical texts from Hattusa were often written in Hattic [and] Hurrian . . .even after Hittite became the norm for other writings." This is similar to the survival of Sumerian for religious purposes until around the 1st century BCE, despite the fact that it was replaced by the Semitic language Akkadian in general use roughly 1800 years earlier.

The Early Hittites

The first historical record of an Indo-European language is of Hittite in eastern Anatolia. An Indo-European Hittite language speaking dynasty dates back to at least 1740 BCE in a central Anatolian city (see generally here).

The Hittites called their own language the "language of Nesa," which is the name in Hittite of the ancient city of Kanesh, about 14 miles Northwest of the modern city of Kayseri in central Anatolia. This was an ancient Anatolian city, of pre-literate non-Indo-European language speaking farmers to which an Akkadian language speaking trading colony attached itself as a suburb for about two hundred years until around 1740 BCE.

Around 1740 BCE, the Assyrian culture ends and a Hittite culture appears in the archeological record, when the city was taken by Pithana, the first known Hittite king.

The Hittites of Nesa conquered this city from Kussara, which is believed to be between the ancient cities of Nesa and Aleppo (which was first occupied as a city around 5000 BCE), which continues to be a major city in Northern Syria also known as Halab. Their first king was described as the king of this one city-state.

His son, Anitta, sacked Hattsua around 1700 BCE and left the earliest known written Hittite inscription. Kanesh is closer to the source of the Red River than Hattsua, which would later become the Hittite capitol, and was ruled at the time of the sack by Hattic king Piyusti whom he defeated. The text of Anitta's inscription translates to:

Anitta, Son of Pithana, King of Kussara, speak! He was dear to the Stormgod of Heaven, and when he was dear to the Stormgod of Heaven, the king of Nesa [verb broken off] to the king of Kussara. The king of Kussara, Pithana, came down out of the city in force, and he took the city of Nesa in the night by force. He took the King of Nesa captive, but he did not do any evil to the inhabitants of Nesa; instead, he made them mothers and fathers. After my father, Pithana, I suppresed a revolt in the same year. Whatever lands rose up in the direction of the sunrise, I defeated each of the aforementioned.

Previously, Uhna, the king of Zalpuwas, had removed our Sius from the city of Nesa to the city of Zalpuwas. But subsequently, I, Anittas, the Great King, brought our Sius back from Zalpuwas to Nesa. But Huzziyas, the king of Zalpuwas, I brought back alive to Nesa. The city of Hattusas [tablet broken] contrived. And I abandoned it. But afterwards, when it suffered famine, my goddess, Halmasuwiz, handed it over to me. And in the night I took it by force; and in its place, I sowed weeds. Whoever becomes king after me and settles Hattusas again, may the Stormgod of Heaven smite him!

The capitol of the Hittites is moved to Hattsua within a century or two. The Hittites sacked Babylon around 1595 BCE.

The Hittites did not inhabit the North Black Sea plain of Anatolia to the Northeast, however. In this region, they were blocked by the Kaskians who make their first appearance three hundred years into the Hittite written record, around 1450 BCE, when they took the Hittite holy city of Nerik to the North of the then Hittite capitol of Hattsua. Less than a century before the Kaskians sacked the city of Nerik and moved to Anatolia, the Kaskians conquered the Indo-European Palaic language speaking people of Northwest Anatolia.

The Kaskians probably hailed from the Eastern shores of the sea of Marmara, which is the small sea between the Black Sea and the Mediterranean.  The Kaskians continued to harry the Hittites for centuries, sacking Hattsua ca. 1280 BCE, although Hattsua was retaken as was the city of Nerik which they had again lost to the Kaskians. The Kaskians in an alliance with the Mushki people, toppled the Hittite empire around 1200 BCE, were then repulsed by the Assyrians, and appear to have migrated after being defeated by the Assyrians to the West Caucuses.

The Mushki were a people of Eastern Anatolia or the Caucuses, associated with the earliest history of state formation for Caucasian Georgia and Armenia. This suggests that they were likely non-Indo-European speakers, at least originally, although they may have adopted the local Luwian language of their subjects in Neo-Hittite kingdoms that arose after the fall of the Hittite empire in East Anatolia.

From about 1800 BCE to 1600 BCE, the city of Aleppo ruled the Kingdom of Yamhad based there and ruled by an Amorite dynasty.  The Amorites were a linguistically North Semitic people.  There had been Amorite dynasties in the same general region for two hundred years before then (i.e. since at least around 2000 BCE). This fell to the Hittites sometime in the following century (i.e. sometime between 1600 BCE and 1500 BCE) and was subsquently close to the boundary between the Egyptians to the Southwest, the Mesopotamian empires to the Southeast, and the Hittites to the North, for hundreds of years. There was a non-Indo-European Hurrian minority in Yamhad that exerted a cultural influence on the Kingdom and on its ruling Amorites who were a Semitic people whose language was probably ancestral to all of the Semitic languages (including Aramahic, Hebrew and Arabic), except Akkadian and language of Ebla, which is midway between Akkadian and the North Semitic language of the Amorites.

The Amorites a.k.a. the Mat.Tu were described as of sometime around the 21st century BCE as follows in Sumerian records (citing E. Chiera, Sumerian Epics and Myths, Chicago, 1934, Nos.58 and 112; E. Chiera, Sumerian Texts of Varied Contents, Chicago, 1934, No.3.)

The MAR.TU who know no grain.... The MAR.TU who know no house nor town, the boors of the mountains.... The MAR.TU who digs up truffles... who does not bend his knees (to cultivate the land), who eats raw meat, who has no house during his lifetime, who is not buried after death...

They have prepared wheat and gú-nunuz (grain) as a confection, but an Amorite will eat it without even recognizing what it contains!

In other words, the early pre-dynastic Amorites were probably nomadic herders.

The ancient Semitic city of Ebla was 34 miles southwest of Aleppo and was destroyed between 2334 BCE and 2154 BCE by an Akkadian king. It had a written language between Akkadian and North Semitic written from around 2500 BCE to 2240 BCE and was a merchant run town trading in wood and textiles whose residents also had a couple hundred thousand herd animals. The early Amorites were known to the people of Elba as "a rural group living in the narrow basion of the middle and upper Euphrates"(original source: Giorgio Bucellati, "Ebla and the Amorites", Eblaitica 3 (New York University) 1992:83-104), although Ebla would later become a subject kingdom of Yamhad.  The Akkadian kings campaigned against the Amorites following the fall of Ebla and recognized them as the main people to the West of their empire, whose other neighbors were the Subartu (probably Hurrians) to the Northeast, Sumer (in South Mesopotamia) and Elam (in the Eastern mountains).

The oldest Akkadian writing is found around 2600 BCE.

The Hittite, Mittani and Egyptians at 1400 BC

By around 1400 BCE, the Hittites ruled an area corresponding to the Red River (a.k.a. Kizilirmak basin) (map here citing Cambridge Ancient History Vol II Middle East & Aegean Region 1800-1300. I. E. S. Edwards (Ed) et al. as its source).

Adjacent to the Hittites to the Southeast, the Mittani empire, with commoners who spoke a non-Indo-European language called Hurrian and a ruling class that spoke an Indo-European language very close to Sanskrit, ruled the upper Euphrates and Tigris river valley about as far South as modern day Hadithah and Tikrit in Iraq. The Mittani also had a small piece of the Levant, extending Southwest to roughly the modern boundary between Turkey and Syria.

To the South of the Mittani in the East, the Kassite empire ruled the lower Euphrates and Tigris river valleys. The Kassites were a non-Indo-European Hurrian speaking people from the neighboring Zargos mountains to the East of the Mittani. The Kassites wrested power from the Akkadian empire.  The Akkadian empire, and its Semitic Akkadian language, in turn, had replaced the non-Indo-European, non-Semitic Sumerian language used before the Akkadian empire emerged.

To the Southwest of the Mittani were the Egyptians.  The Egyptian ruled from the Mittani boundary in the Levant to the greater Nile Delta in Northeast Africa.

The Hittites At Their Peak

Half a century later later, at its greatest extent, under Kings Suppiluliuma I(c.1350–1322) and Mursili II (c.1321–1295), the Hittite Empire included all of Anatolia (including Troy) except the immediate vicinity of modern Istanbul, the Levant from modern Turkey to a little bit North of Beruit on the coast and as far South as what is today Damascus further inland, and the ancient city of Mari, which is situated very close to where the Euphrates river crosses the modern Syrian border. (Map here).

The Hittites had absorbed all of the Mittani empire except some of its lands in the upper Tigris, and extended to the South the Mittani border with Egypt.

The End of the Hittite Empire and the Anatolian languages

A civil War followed by a series of regional events roughly contemporaneous with the Trojan War of the Greek epics and various historical accounts lumped together as part of the "Bronze Age collapse" destroyed the Hittite empire around 1200 BC. The Hittite language is replaced by successor languages after the Hittite empire falls.

Following this peak, one of the Anatolian languages was the Luwian language, which may have been the language of the Trojans. Luwain may have actually been a sister language of Hittite and equally old, as attested by its early use as a liturgical language along with pre-Indo-European languages of the area. Luwain may also have been an evolutionary linguistic predecessor to Hittite proper.

Luwain, in turn, evolved into the Lycian. See Bryce, Trevor R., "The Lycians - Volume I: The Lycians in Literary and Epigraphic Sources" (1986)). Other Anatolian languages including Lycian were successor Anatolian languages to Hittite that were spoken in Anatolia through the first century BCE.  Then, in the first century BCE, Alexander the Great conquered an area including Anatolia, and made Greek, which is a neighboring Indo-European language, the language of his kingdom.

Recap of Anatolian History 

All of the Indo-European Anatolian languages (with the possible exception of Luwian) spoken from around 1740 BCE to about 100 BCE, when they were replaced by Greek under Alexander the Great, trace their roots to the city-state they established by conquering the pre-existing city of Kanesh in central Anatolia.

There is no evidence for the presence of any Indo-European languages in Anatolia prior to about 2000-1800 BCE, and the available historical record seems to indicate that early Anatolian populations of Indo-Europeans were mere pockets of people at the time who may very likely have been recent arrivals.

Armenian is not an Anatolian language and is most closely related linguistically to Greek, but with many non-Indo-European and Indo-Iranian areal influences.  Armenian may have arrived in its current location shortly after the fall of the Hittite empire in a folk migration from Western Anatolia, the Aegean, or the Balkans.  It is sometimes associated with the Phrygians.

Post-Script: The Tocharians

[This fragment not about the Hittites is also salvaged from this old post.]

The oldest mummies in the Tarim basin of what is now Ugygur China (i.e. in the Xinjiang Uyghur Autonomous Region) in the far Northeast of modern China also date to 1800 BCE.

Pliny the Elder, in Rome, recounts a first century CE report from an ambassador to China from Ceylon who later served as an ambassador to the Roman empire, that corroborates the existence of people with this appearance and a language unlike those known locally.

Quark Masses Matter

Most of the mass in hadrons formed only by up, down and strange quarks comes from the binding energy of their gluon fields, and not from the rest mass of the quarks themselves.

But, that doesn't mean that the quark masses don't matter.  Lattice QCD studies of a model in which pions have a mass of 300 MeV rather than 135-139 MeV, which imply heavier quark masses than those present in reality, leads to QCD behavior very different from what is observed in real life.

For example, if up and down quarks were heavier than they are, particles make of two neutrons and no protons, would be stable, something that isn't the case in the real world.

Thus, binding energy in hadrons depends upon quark masses in a quite sensitive and non-linear way.

ATLAS Excludes CP-Odd Higgs At 220-1000 GeV

In models with two (or more) Higgs doublets, there are five or more Higgs bosons, rather than one as in the Standard Model.  The four extra Higgs bosons are customarily called H+, H-, A and h (or H), with H and h being CP-Even Higgs one heavier and one lighter, and A being a CP-Odd Higgs boson.

The A is excluded with 95% confidence at masses from 220 GeV to 1000 GeV by existing LHC measurements by the ATLAS experiment.  Two Higgs doublets are generically present in all SUSY models and in many other non-SUSY models beyond the Standard Model as well.

The 125 GeV Higgs boson is CP-Even as expected.

Meanwhile, the CMS experiment has produced more SUSY exclusions, because there is still not any sign of supersymmetry at the LHC.

Previous discussions of the theoretical and experimental barriers to two Higgs doublet models also dis favor the model, but a two Higgs doublet model has been proposed to explain multiple modest anomalies in LHC data.

Reich Paper Offers Wealth Of European Ancient DNA

A pre-print of a new paper by Reich, et al., offers a wealth of new ancient DNA information for Europe, including Y-DNA, mtDNA and autosomal DNA from the Mesolithic era through the late Bronze Age.

Most eagerly awaited is the new Y-DNA data (internal citations omitted):

We determined that 34 of the 69 newly analyzed individuals were male and used 2,258 Y chromosome SNPs targets included in the capture to obtain high resolution Y chromosome haplogroup calls. Outside Russia, and before the Late Neolithic period, only a single R1b individual was found (early Neolithic Spain) in the combined literature (n=70). By contrast, haplogroups R1a and R1b were found in 60% of Late Neolithic/Bronze Age Europeans outside Russia (n=10), and in 100% of the samples from European Russia from all periods (7,500-2,700 BCE; n=9). R1a and R1b are the most common haplogroups in many European populations today and our results suggest that they spread into Europe from the East after 3,000 BCE. Two hunter-gatherers from Russia included in our study belonged to R1a (Karelia) and R1b (Samara), the earliest documented ancient samples of either haplogroup discovered to date. These two hunter-gatherers did not belong to the derived lineages M417 within R1a and M269 within R1b that are predominant in Europeans today, but all 7 Yamnaya males did belong to the M269 subclade of haplogroup R1b.

The big surprise is that all of the Yamnaya Y-DNA was R1b-M269, which is now typical of Western Europe and the Northern European coast, in addition to the R1b of Samara which was a Mesolithic (i.e. hunter-gatherer) culture that preceded the Yamnaya culture in essentially the same geographic location. R1b-M269 is predominant in the Basque people, despite the widely held belief that their ancestors were not linguistically Indo-European, and the only Bell Beaker individual for whom Y-DNA data has been obtained (from Germany) is also R1b-M269.

Conventional wisdom had expected that the Yamnaya people were R1a-M417 bearing men who gave rise to the Corded Ware culture that produced the Y-DNA R1a predominance seen in Central and Eastern Europe today.  The genetic evidence tends to favor a NE European rather than SE European proximate source of R1a in Central Europe.

Karelia where the Mesolithic R1a sample was found is in modern day Russia just to the east of Finland.

The autosomal DNA data also provides new insights but is not so easily summarized.  Some notable observations:

* Eight of the nine Bell Beaker individuals for whom ancient autosomal DNA is available (all from one of two sites in Germany) are women.  Bell Beaker individuals have a considerably smaller Ancestral North European component than contemporaneous Corded Ware culture individuals.

* There are eight ancient autosomal DNA samples from the Unetice culture from sites in Germany. They have very similar automsomal DNA profiles to the Bell Beaker individuals.  But despite this similarity, all three of the men in the Unetice sample have Y-DNA I2.

* Y-DNA I2 is also found in five Swedish Mesolithic men, one early Neolithic man from Spain, two Middle Neolithic men from Spain, one Middle Neolithic man from Germany, one late Neolithic man from Germany, and two early Bronze Age men from Germany.

* The branching trees created using autosomal DNA similarities do not match the ones that would be inferred from Y-DNA data.

* The population discontinuity between the first farmers of Europe (LBK, etc.) and the linguistically Indo-European R1a/R1b populations that followed disfavors the Anatolian hypothesis of Indo-European language origins.