The Turkic Origins Of The Tang Dynasty

One of the most important Chinese dynasties was derived from a nomadic Turkic tribe.

By examining the record of a local anti-Tibetan rebellion in document scroll S.1438 from the Dunhuang “library cave,” this discussion demonstrates that the nomadic Tuoba origin of the Tang royal house was known not only to the ancient Turkic people, as shown by their name for the Tang, Tabγač, but also to the Tang subjects themselves. In addition to substantiating Paul Pelliot’s old assertion that the Old Turkic name Tabγač came from the name Tuoba, this work argues that the Tang dynasty was in many aspects indeed the continuation of its Tuoba predecessors.

Sanping Chen, “The Tang as a Tuoba Dynasty” (pdf), 356 Sino-Platonic Papers (2024) via Language Log.

Sterile Neutrino Dark Matter Constrained

A new paper largely rules out sterile neutrino dark matter with sterile neutrinos having masses of less than 4,000 eV. Active neutrinos can't be much more than 0.5 eV, almost ten thousand times less massive than that. It also presses up against hard upper bounds on the mass of warm dark matter particles, never mind that warm dark matter models with sterile dark matter particles have been shown to produce dark matter distributions inconsistent with what is observed.

This paper is one more cut in the death of a thousand cuts that dark matter particle theories are experiencing. 

Low-mass galaxies provide a powerful tool with which to investigate departures from the standard cosmological paradigm in models that suppress the abundance of small dark matter structures. One of the simplest metrics that can be used to compare different models is the abundance of satellite galaxies in the Milky Way. Viable dark matter models must produce enough substructure to host the observed number of Galactic satellites. 

Here, we scrutinize the predictions of the neutrino Minimal Standard Model (νMSM), a well-motivated extension of the Standard Model of particle physics in which the production of sterile neutrino dark matter is resonantly enhanced by a lepton asymmetry in the primordial plasma. This process enables the model to evade current constraints associated with non-resonantly produced dark matter. 

Independently of assumptions about galaxy formation physics we rule out, with at least 95 per cent confidence, all parameterizations of the νMSM with sterile neutrino rest mass, Ms ≤ 1.4keV. Incorporating physically motivated prescriptions of baryonic processes and modelling the effects of reionization strengthen our constraints, and we exclude all νMSM parameterizations with Ms ≤ 4keV. Unlike other literature, our fiducial constraints do not rule out the putative 3.55 keV X-ray line, if it is indeed produced by the decay of a sterile neutrino; however, some of the most favoured parameter space is excluded. 

If the Milky Way satellite count is higher than we assume, or if the Milky Way halo is less massive than M(MW)(200) = 8×10^11 M⊙, we rule out the νMSM as the origin of the 3.55 keV excess. 

In contrast with other work, we find that the constraints from satellite counts are substantially weaker than those reported from X-ray non-detections.

Oliver Newton, et al., "Constraints on the properties of νMSM dark matter using the satellite galaxies of the Milky Way" arXiv:2408.16042 (August 28, 2024).

Another study finds that gravitino dark matter would have to have masses in the range of 1 TeV or greater (possibly much greater) which has myriad problems of its own, largely ruling out this dark matter candidate as a practical matter.

The a(0)(980) Meson Explained

One of the long standing mysteries in high energy physics is determining the internal structure of scalar mesons such as the a(0)(980) meson, and they aren't easily explained with a quark-antiquark model (apart from distinctive quarkonium cases, where the quark and antiquark are quarks of the same flavor, like a charm quark- anticharm quark meson).

The symbols "a" (isospin 1) and "f" or "f'" (isospin 0) apply to mesons with ground state JPC quantum numbers 0++ which are also known as (true) scalar mesons.

A new paper concludes with convincing reasoning that the a(0)(980) meson, a scalar meson, is a tetraquark. A key part of the abstract to the paper explains that:

The predicted branching fractions in the qq¯ model of a0(980) are too small by one to two orders of magnitude compared to experiment as the amplitude is suppressed by the smallness of the a0(980)+ decay constant, while those for D+→a0(980)0P and D0→a0(980)−P are usually too large. These discrepancies can be resolved provided that a0(980) is a tetraquark state.

The Double Slit Experiment In A Nutshell

 

The Olympics In The Bronze Age

Solar System Constraints On Primordial Black Hole Dark Matter

A paper based upon solar system dynamics largely rules out the remaining parameter space for primordial black holes. The abstract states:

N.B.: A solar mass is about 2*10^33 grams. So, this is equivalent to a range of 10^-15 to 10^-11 solar masses.

The Latest T2K Neutrino Results Favor A Normal Mass Ordering

New neutrino oscillation data from T2K continues to strongly favor a normal mass ordering over an inverted mass ordering. Cosmology based bounds on neutrino masses also favor a normal mass ordering. Direct measurements of neutrino mass are not discerning enough to distinguish between the possibilities.

There is a more mild preference for θ₂₃ value in the upper octant. This parameter is roughly 49°±1° in the upper octant and 41º ±1°in the lower octant.

Illustration from here.

Non-zero CP violation in neutrino oscillation is preferred by more than two sigma, but estimates of the amount of CP violation in neutrino oscillation are very imprecise.

Origin Of Dinosaur Killing Object Located

It is pretty stunning that this 66 million year old mystery can be solved at all. 

The key was the chemical composition of the impactor, which contained Ruthenium. This is almost completely absent on Earth apart from rare extraterrestrial impactors, and is also absent in other impactor candidates, including comets and "siliceous asteroids, a class that formed closer to the sun than carbonaceous asteroids and that are concentrated in the asteroid belt between Mars and Jupiter. Most meteorites that end up on Earth’s surface are from this siliceous family."

Unusual Origin Found for Asteroid That Killed the Dinosaurs

A study adds strong evidence to the hypothesis that the deadly rock came from a family of objects that originally formed well beyond the orbit of the planet Jupiter. . . .

The nature of this apocalyptic object, known as the Chicxulub impactor, has inspired intense debates, including a long-running dispute over whether it was a comet or an asteroid. But evidence has been mounting in recent years that the roughly six-mile-wide impactor belonged to a family of asteroids that formed beyond the orbit of Jupiter, and that rarely impact Earth.

Now, a team led by Mario Fischer-Gödde, a research scientist at the University of Cologne in Germany, has bolstered that case with the help of the rare element ruthenium. Ruthenium is abundant in asteroids but extremely scarce in Earth’s crust, making it a handy bellwether of past impacts by space rocks. The team searched for isotopes of ruthenium in the geological remnants of the Chicxulub impact.

The results revealed a uniform signature across the global layer of debris left by the impact, which is known as the Cretaceous-Paleogene (K-Pg) boundary. And that signature neatly matches the makeup of a group of space rocks known as carbonaceous asteroids because of their high-carbon content, according to a study published on Thursday in Science.

From the New York Times. 

Remains Of 1181 CE Supernova Found

Chinese astronomers without telescopes saw a "guest star" as bright as Saturn in the year 1181 CE for about six months, which is now understood to have been a supernova. 

The remnants of it, and the particular type of supernova it was, a Type 1ax formed when two white dwarfs make an incomplete merger, have now been determined.

Jurassic Mammals Lived Longer But Matured Later

In the Jurassic era early mammals lived much longer, but matured much later, impairing their ability to overcome threats to their respective species by reproducing early and often. Evolutionary fitness favored the modern pattern.

Researchers were able to image tiny growth rings in fossilized root cement -- the bone tissue that attaches the teeth to the jaw. "The rings are similar to those in trees, but on a microscopic level," explains Professor Thomas Martin of the Vertebrates -- Mammals working group at the University of Bonn Institute of Organismic Biology, who is a senior author of the study. "Counting the rings and analyzing their thickness and texture enabled us to reconstruct the growth patterns and lifespans of these extinct animals."

The researchers determined that the first signs of the growth patterns characteristic of modern mammals, such as a puberty growth spurt, started emerging roughly 150 million years ago. Early mammals grew much more slowly but lived substantially longer than today's small mammals, with lifespans of eight to fourteen years instead of just one or two as in modern mice, for example. However, it took early mammals years to reach sexual maturity, again in contrast to their modern descendants which reach sexual maturity in just a few months.

From Science Daily citing Elis Newham, et al., "The origins of mammal growth patterns during the Jurassic mammalian radiation." 10(32) Science Advances (2024) DOI: 10.1126/sciadv.ado4555

Directly Measuring High Energy Neutrino Cross-Sections

Particle collider experiments have confirmed that electron neutrinos and muon neutrinos have their predicted cross-sections of interaction.

There are three types, or flavors, of neutrinos: electron neutrinos (ν(e)), muon neutrinos (ν(μ)), and tau neutrinos (ν(τ)). So far, most neutrinos studied by researchers have been low-energy neutrinos. To date, neutrino interaction cross sections, which is the probability of a neutrino interacting with a target particle, had not been measured at energies above 300 gigaelectronvolts (GeV) for electron neutrinos and between 400 GeV and six teraelectronvolts (6000 GeV) for muon neutrinos.

In a groundbreaking study, a team of researchers . . . utilized the Forward Search Experiment (FASER) at CERN's Large Hadron Collider (LHC), to achieve the first direct observation of high energy electron and muon neutrino interactions at a particle collider. . . . The FASERν emulsion detector is made of 730 layers of interleaved tungsten plates and emulsion films, with a total target mass of 1.1 tons. The researchers analyzed a subset of the exposed detector volume, corresponding to a mass of 128.6 kg, for high-energy neutrinos from the LHC pp collisions. After applying strict criteria, selecting events with electrons or muons with an energy above 200 GeV, four electron neutrino interaction candidate events and eight muon neutrino interaction candidate events were observed. These interactions had high statistical significance (5.2σ for electron neutrinos and 5.7σ for muon neutrinos), meaning they are highly unlikely to be random background fluctuations and therefore represent actual neutrinos.

The neutrinos detected in the study had energies in the teraelectronvolts range, the highest ever detected from an artificial source. This study marks the first measurement of neutrino interaction cross-sections in the unexplored energy range of 560-1740 GeV for electron neutrinos and 520-1760 GeV for muon neutrinos. Additionally, the measured interaction cross-sections were consistent with Standard Model predictions.

From Science Daily citing: Roshan Mammen Abraham, et al., "First Measurement of ν(e) and ν(μ) Interaction Cross Sections at the LHC with FASER’s Emulsion Detector." 133(2) Physical Review Letters (2024). DOI: 10.1103/PhysRevLett.133.021802

The abstract of the paper states that:

The first results of the study of high-energy electron neutrino (𝜈𝑒) and muon neutrino (𝜈𝜇) charged-current interactions in the FASER⁢𝜈 emulsion-tungsten detector of the FASER experiment at the LHC are presented. A 128.8 kg subset of the FASER⁢𝜈 volume was analyzed after exposure to 9.5  fb−1 of √𝑠=13.6  TeV 𝑝⁢𝑝 data. Four (eight) 𝜈𝑒 (𝜈𝜇) interaction candidate events are observed with a statistical significance of 5.2⁢𝜎 (5.7⁢𝜎). This is the first direct observation of 𝜈𝑒 interactions at a particle collider and includes the highest-energy 𝜈𝑒 and 𝜈𝜇 ever detected from an artificial source. The interaction cross section per nucleon 𝜎/𝐸𝜈 is measured over an energy range of 560–1740 GeV (520–1760 GeV) for 𝜈𝑒 (𝜈𝜇) to be (1.2+0.8−0.7)×10−38  cm2 GeV−1 [(0.5±0.2)×10−38  cm2 GeV−1], consistent with standard model predictions. These are the first measurements of neutrino interaction cross sections in those energy ranges.

The body text indicates that the expected number of events in the Standard Model prediction (with a plus or minus one sigma range) was 1.1-3.3 for electron neutrinos and 6.5-12.4 for muon neutrinos. The number of electron neutrino events was within two sigma of the prediction, and the number of muon neutrino was right in the middle of the predicted range.