Wednesday, April 21, 2021

A Short Guide To Beyond The Standard Model Physics Proposals That Are Wrong

A June 4, 2019 paper from the LHC reviews a plethora of beyond the Standard Model theories, most of which are motivated by supersymmetry or grand unified theory (GUT) models. It is one of the more comprehensive and up to date available reviews of such models.

Every single one of these theories is completely wrong.

These theories are the Lotus eater traps of modern physics that should be dead on arrival and summarily rejected in any serious effort to understand our reality.

Not a single one of them can even reproduce all of the particles of the Standard Model, without creating any particles that are not observed, or phenomena that have not been experimentally ruled out. 

The more compliant supersymmetry (SUSY) models are with experimental constraints, the less well they achieve the purposes for which they were designed.

It shocks me, to some extent, that it seems as if almost no one has even seriously tried to produce a model with no right handed neutrinos, no extra Higgs bosons, no other new fermions or bosons, no dark matter candidates, three generations of fundamental fermions, and that preserves baryon number and lepton number. 

But, perhaps this is simply because the entire enterprise is doomed,  and ill motivated by observational evidence in the first place, and it simply can't be done.

Some of these models explain charged lepton flavor universality violations (usually with leptoquarks), which is pretty much the only significant anomaly between the Standard Model and observation that hasn't been ruled out (or seems likely to be ruled out soon based upon what we know), but even if the anomaly turns out to be real, my own sense is that the solutions proposed to explain these anomalies are almost certainly not the correct ones.


neo said...

It shocks dark matter candidates

why shocking ?

dark matter remains the accepted explanation of the missing mass

andrew said...


There isn't just one accepted explanation. There hasn't been for a long time.

Moreover, because this question has received so much experimental and observational attention, exclusions of dark matter candidates have been filling more and more of the parameter space.

SUSY and GUT dark matter candidates have lots of model defined properties, like a significant cross section of interaction with ordinary baryonic matter at least as strong as neutrinos in most cases and particular mass ranges and particular spins that make them much easier to rule out with direct dark matter detection experiments and annihilation and decay product searches and particle collider signatures and thermal relic origins that make the available parameter space for those candidates to rule out. Generically, SUSY and GUT theories produce WIMP candidates that have some non-gravitational interactions.

Also, while it makes sense to have some BSM models with DM particle candidates, it doesn't make sense for all of them to have them. Somebody ought to be working on models without RH neutrinos. Somebody ought to be working on models without two or more Higgs doublets. Somebody ought to be working on models without Majorana neutrinos. Somebody ought to be riding the dark horse candidate.

Hut the group think is so overwhelming that nobody in the field is doing that and that the entire GUT sub-discipline is just not paying attention to the growing experimental constraints on the kinds of DM candidates that they are proposing.

Nobody is even proposing models that have exclusively the SM + the Graviton + either gravitinos or axions (both of which can be suitably light, have very weak non-gravitational copulings, and can be singlets) as DM candidates.

At least in the 1980s, when they were coming up with SUSY and SUGRA and GUT models to start with, the ideas were fresh and innovative. These days, arXiv and major LHC theorists are still rehashing these decades old models instead of thinking out of the box.

This isn't just one theorist stuck in a rut. There are hundreds of some of the highest IQ people on the planet with full time jobs devoted to coming up with these theories and they are so collectively complacent and stagnant.

neo said...

there's smash

andrew said...

There is. "We extend the SM with a new complex singlet scalar
field σ and two Weyl fermions Q and Q˜ in the 3 and
¯3 representations of SU(3)c and with charges −1/3
and 1/3 under U(1)Y . With these charges, Q and Q˜
can decay into SM quarks, which ensures that they
will not become too abundant in the early Universe.
We also add three RH fermions Ni."

Three right handed neutrinos, a new force carrying scalar boson, and two new fundamental particles, plus baryon number and lepton number violation. Old wine in new skins, but not the worse of them.

andrew said...

A slightly more interesting one. (Twistor Unification).

neo said...

Constraints on ultralight scalar bosons within black hole spin measurements from LIGO-Virgo's GWTC-2
Ken K. Y. Ng, Salvatore Vitale, Otto A. Hannuksela, Tjonnie G. F. Li

Clouds of ultralight bosons - such as axions - can form around a rapidly spinning black hole, if the black hole radius is comparable to the bosons' wavelength. The cloud rapidly extracts angular momentum from the black hole, and reduces it to a characteristic value that depends on the boson's mass as well as on the black hole mass and spin. Therefore, a measurement of a black hole mass and spin can be used to reveal or exclude the existence of such bosons. Using the black holes released by LIGO and Virgo in their GWTC-2, we perform a simultaneous measurement of the black hole spin distribution at formation and the mass of the scalar boson. We find that the data strongly disfavors the existence of scalar bosons in the mass range between 1.3×10−13 eV and 2.7×10−13 eV for a decay constant fa≳1014 GeV. The statistical evidence is mostly driven by the two {binary black holes} systems GW190412 and GW190517, which host rapidly spinning black holes. The region where bosons are excluded narrows down if these two systems merged shortly (∼105 years) after the black holes formed.

Mitchell said...

Some day there should be a discussion about Woit's paper, e.g. whether it has something in common with

andrew said...

@Mitchell Thanks for the link. I've seen a couple of papers proposing something similar but the one that you link to is quite elegant.