Monday, September 26, 2022

A Rare Physics Op-Ed

The Guardian Newspaper has a rare opinion-editorial article about the value of certain kinds of theoretical and phenomenological physics research headlined:
No one in physics dares say so, but the race to invent new particles is pointless: In private, many physicists admit they do not believe the particles they are paid to search for exist – they do it because their colleagues are doing it. 

It was written by Sabine Hossenfelder who, as usual, is spot on in challenging the practice she describes not as entirely invalid, but as having minimal value. It begins playfully:

Imagine you go to a zoology conference. The first speaker talks about her 3D model of a 12-legged purple spider that lives in the Arctic. There’s no evidence it exists, she admits, but it’s a testable hypothesis, and she argues that a mission should be sent off to search the Arctic for spiders.

The second speaker has a model for a flying earthworm, but it flies only in caves. There’s no evidence for that either, but he petitions to search the world’s caves. The third one has a model for octopuses on Mars. It’s testable, he stresses.
She continues:
Almost every particle physics conference has sessions just like this, except they do it with more maths. It has become common among physicists to invent new particles for which there is no evidence, publish papers about them, write more papers about these particles’ properties, and demand the hypothesis be experimentally tested. Many of these tests have actually been done, and more are being commissioned as we speak. It is wasting time and money.

Since the 1980s, physicists have invented an entire particle zoo, whose inhabitants carry names like preons, sfermions, dyons, magnetic monopoles, simps, wimps, wimpzillas, axions, flaxions, erebons, accelerons, cornucopions, giant magnons, maximons, macros, wisps, fips, branons, skyrmions, chameleons, cuscutons, planckons and sterile neutrinos, to mention just a few. We even had a (luckily short-lived) fad of “unparticles”.

All experiments looking for those particles have come back empty-handed, in particular those that have looked for particles that make up dark matter, a type of matter that supposedly fills the universe and makes itself noticeable by its gravitational pull. However, we do not know that dark matter is indeed made of particles; and even if it is, to explain astrophysical observations one does not need to know details of the particles’ behaviour. The Large Hadron Collider (LHC) hasn’t seen any of those particles either, even though, before its launch, many theoretical physicists were confident it would see at least a few.

Talk to particle physicists in private, and many of them will admit they do not actually believe those particles exist. . . .  

[T]he biggest contributor to this trend is a misunderstanding of Karl Popper’s philosophy of science, which, to make a long story short, demands that a good scientific idea has to be falsifiable. Particle physicists seem to have misconstrued this to mean that any falsifiable idea is also good science.

In the past, predictions for new particles were correct only when adding them solved a problem with the existing theories. For example, the currently accepted theory of elementary particles – the Standard Model – doesn’t require new particles; it works just fine the way it is. The Higgs boson, on the other hand, was required to solve a problem. The antiparticles that Paul Dirac predicted were likewise necessary to solve a problem, and so were the neutrinos that were predicted by Wolfgang Pauli. The modern new particles don’t solve any problems.

In some cases, the new particles’ task is to make a theory more aesthetically appealing, but in many cases their purpose is to fit statistical anomalies. Each time an anomaly is reported, particle physicists will quickly write hundreds of papers about how new particles allegedly explain the observation. . . . 

Ambulance-chasing is a good strategy to further one’s career in particle physics. . . . since ambulance-chasers cite each other’s papers, they can each rack up hundreds of citations quickly. But it’s a bad strategy for scientific progress. . . .  
I believe there are breakthroughs waiting to be made in the foundations of physics; the world needs technological advances more than ever before, and now is not the time to idle around inventing particles, arguing that even a blind chicken sometimes finds a grain. As a former particle physicist, it saddens me to see that the field has become a factory for useless academic papers.
Also, note that criticism of physics scholarship really has two parts: 

(1) particles "to make a theory more aesthetically appealing", which aren't actually needed (like axions, see-saw mechanism neutrinos, supersymmetric particles and extra Higgs bosons), and 

(2) particles to explain statistical anomalies (often from one or two recent experiments) which have not adequately exhausted explanations that don't require new physics (like the X17 particle, leptoquarks to explain lepton universality violations in semi-leptonic B meson decays, sterile neutrinos, and new particles proposed to explain a W boson mass measurement out of step with other recent W boson mass measurements).

But, both are out of hand and a waste of time and money that would be better spent focusing on more well motivated proposals.

The author further discusses the Op-Ed at her blog.

13 comments:

neo said...

btw

Atomki anomaly


High Energy Physics - Phenomenology
[Submitted on 19 Sep 2022]
Light Z′ Signatures at the LHC
Yaşar Hiçyılmaz, Shaaban Khalil, Stefano Moretti

We propose a theoretical framework embedding a spontaneously broken U(1)′ symmetry in addition to the Standard Model (SM) gauge group, from which a very light Z′ state emerges, with both vector and axial (non-universal) couplings to fermions, able to explain the so-called Atomki anomaly, compliant with current measurements of the Anomalous Magnetic Moments (AMMs) of electron and muon as well as beam dump experiments while providing a distinctive pp→Higgs→Z′Z′→4l (l=e,μ) signal at the Large Hadron Collider (LHC), where the `Higgs' label refers to the SM-like Higgs state discovered in 2012 or a lighter one. We finally show that the cross section for this process should be sufficiently large to afford one with significant sensitivity during Run 3 of the LHC.

Subjects: High Energy Physics - Phenomenology (hep-ph)
Cite as: arXiv:2209.09226 [hep-ph]

Z' boson U(1)′ symmetry

andrew said...

@neo

This is exactly the kind of worthless physics paper she is describing, and the "Atomki anomaly" doesn't stand up to scrutiny.

neo said...

what is worthless about U(1)′ symmetry and Z' boson? here to explain Atomki anomaly"

it was suggested in 1994 decades ago before the "Atomki anomaly"

"This Z′ boson arises from a very simple extension to the Standard Model,"
"with a Z′-portal Majorana fermion dark matter"

now to explain Atomki anomaly

Light Z′ and Dark Matter from U(1)X Gauge Symmetry​

Nobuchika Okada, Satomi Okada, Qaisar Shafi

We consider a U(1)X gauge symmetry extension of the Standard Model (SM) with a Z′-portal Majorana fermion dark matter that allows for a relatively light gauge boson Z′ with mass of 10 MeV− a few GeV and a much heavier dark matter through the freeze-in mechanism. In a second scenario the roles are reversed, and the dark matter mass, in the keV range or so, lies well below the Z′ mass, say, ∼1 GeV. We outline the parameter space that can be explored for these two scenarios at the future Lifetime Frontier experiments including Belle-II, FASER, LDMX and SHiP.



Comments: 18 pages, 4 figures, new references added, typos corrected
Subjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Experiment (hep-ex)
Cite as: arXiv:2003.02667 [hep-ph]

Model for a Light Z' Boson​

R. Foot, X.-G. He, H. Lew, R. R. Volkas

A model of a light Z′ boson is constructed and phenomenological bounds are derived. This Z′ boson arises from a very simple extension to the Standard Model, and it is constrained to be light because the vacuum expectation values which generate its mass also break the electroweak gauge group. It is difficult to detect experimentally because it couples exclusively or primarily (depending on symmetry breaking details) to second and third generation leptons. However, if the Z′ boson is sufficiently light, then there exists the possibility of the two-body decay τ→μZ′ occuring. This will provide a striking signature to test the model.



Comments: 20 pages + 5 pages of figures (appended as postscipt files), LaTeX, OITS-532
Subjects: High Energy Physics - Phenomenology (hep-ph)
Cite as: arXiv:hep-ph/9401250


A Light Z′ Boson​

Xiao-Gang He

A model of a light Z′ boson based on gauged Lμ−Lτ U(1) symmetry is constructed. The Z′ boson mass is constrained to be in the range of 0.8 to 1 GeV from Z and Z′ mass relation, g-2 of muon, and tau decays. The two body decay τ→μZ′ is possible. This will provide a striking signature to test the model. Talk presented at the Eighth Meeting of the American Physical Society, Division of Particles and Fields (DPF'94), Albuqurque, New Mexico, August 2-6, 1994.



Comments: 7pages, REvtex, OITS-549
Subjects: High Energy Physics - Phenomenology (hep-ph)
Cite as: arXiv:hep-ph/9409237

andrew said...

They are all garbage papers.

There is no good motivation for any specific kind of dark matter particle, and certainly not one with a Z' portal creation mechanism. The process should be to determine the properties a particle that could explain dark matter phenomena must have well enough to have a suitable target to search for, and to propose the particle second, instead of simply emptying out the drawer of parts that don't fit anything we're doing now to see if we can make use of them.

This proposal, like so many junk particle proposals "arises from a very simple extension to the Standard Model" as a solution looking for a problem, instead of the other way around.

neo said...


proposals "arises from a very simple extension to the Standard Model" as a solution
adheres to KISS

Z' seems better than X17


it could also explain this the anomaly observed in the decay of 8Be and 4He and 12C


Nuclear Experiment
[Submitted on 22 Sep 2022]
New anomaly observed in 12C supports the existence and the vector character of the hypothetical X17 boson
A.J. Krasznahorkay, A. Krasznahorkay, M. Begala, M. Csatlós, L. Csige, J. Gulyás, A. Krakó, J. Timár, I. Rajta, I. Vajda, N.J. Sas

Employing the 11B(p,γ)12C nuclear reaction, the angular correlation of e+e− pairs was investigated in the angular range of 40∘Θ≤175∘ for five different proton energies between Ep = 1.5 - 2.5 MeV. At small angles (Θ≤120∘), the results can be well interpreted by the internal pair creation process of electromagnetic radiations with E1 and M1 multipolarities and by the external pair creation in the target backing. However, at angles greater than 120∘, additional count excess and anomalies were observed, which could be well accounted for by the existence of the previously suggested hypotetical X17 particle. Our results show that the X17 particle was generated mainly in E1 radiation. The derived mass of the particle is mXc2=16.86±0.17(stat)±0.20(syst) MeV. According to the mass, and to the derived branching ratio (Bx=3.4(3)×10−6), this is likely the same X17 particle, which we recently suggested for describing the anomaly observed in the decay of 8Be and 4He.

Comments: 5 pages, 4 figures. arXiv admin note: text overlap with arXiv:2104.10075, arXiv:2205.07744, arXiv:1910.10459


andrew said...

The father and sons A.J. Krasznahorkay and A. Krasznahorkay have been on every experiment that has claimed to see these and their first claim has largely been debunked as flawed. Their claims as to 8Be and 4He and 12C have descended into the "cries wolf" credibility put until replicated. There is nothing to explain.

And, when there is nothing to explain, Occam's Razor and "Keep it simple stupid" both counsel that one not create new particles that don't actually explain any credible experimental observations.

Mitchell said...

"12-legged purple spider that lives in the Arctic"

They can call it Pycnogonum hossenfelderi when they find it :-)

neo said...


"And, when there is nothing to explain, Occam's Razor and "Keep it simple stupid" both counsel that one not create new particles that don't actually explain any credible experimental observations."

"We propose a theoretical framework embedding a spontaneously broken U(1)′ symmetry in addition to the Standard Model (SM) gauge group, from which a very light Z′ state emerges, with both vector and axial (non-universal) couplings to fermions, able to explain the so-called Atomki anomaly, compliant with current measurements of the Anomalous Magnetic Moments (AMMs) of electron and muon as well as beam dump experiments while providing a distinctive pp→Higgs→Z′Z′→4l (l=e,μ) signal at the Large Hadron Collider (LHC), where the `Higgs' label refers to the SM-like Higgs state discovered in 2012 or a lighter one. We finally show that the cross section for this process should be sufficiently large to afford one with significant sensitivity during Run 3 of the LHC. "

what If during Run 3 of the LHC they've found a very light Z′ state exactly as predicted above ?

Mark B. said...

@neo

There are an infinite number of 'what-if's'. Science does not advance by chasing every one of them. If there were a career downgrade for each one that fails to hold up, you'd see them disappear - quickly.

neo said...

@Mark B.

LHC purpose is to collect and analyze data

neo said...

https://www.physicsforums.com/threads/sabine-hossenfelder-on-the-search-for-new-particles.1045929/

#5

neo said...


High Energy Physics - Experiment
[Submitted on 29 Sep 2022]
Dark sector studies with the PADME experiment
A.P. Caricato, M. Martino, I. Oceano, S. Spagnolo, G. Chiodini, F. Bossi, R. De Sangro, C. Di Giulio, D. Domenici, G. Finocchiaro, L.G. Foggetta, M. Garattini, A. Ghigo, P. Gianotti, T. Spadaro, E. Spiriti, C. Taruggi, E. Vilucchi, V. Kozhuharov, S. Ivanov, Sv. Ivanov, R. Simeonov, G. Georgiev, F. Ferrarotto, E. Leonardi, P. Valente, E. Long, G.C. Organtini, G. Piperno, M. Raggi, S. Fiore, P. Branchini, D. Tagnani, V. Capirossi, F. Pinna, A. Frankenthal

The Positron Annihilation to Dark Matter Experiment (PADME) uses the positron beam of the DAΦNE Beam-Test Facility, at the Laboratori Nazionali di Frascati (LNF) to search for a Dark Photon A′. The search technique studies the missing mass spectrum of single-photon final states in e+e−→A′γ annihilation in a positron-on-thin-target experiment. This approach facilitates searches for new particles such as long lived Axion-Like-Particles, protophobic X bosons and Dark Higgs. This talk illustrated the scientific program of the experiment and its first physics results. In particular, the measurement of the cross-section of the SM process e+e−→γγ at s√=21 MeV was shown.

Subjects: High Energy Physics - Experiment (hep-ex); Instrumentation and Detectors (physics.ins-det)
Cite as: arXiv:2209.14755 [hep-ex]

neo said...

PADME experiment run 3 will verify x17 or rules out