The author of the article is Don Lincoln, a senior scientist in the laboratory at BAC Fermilab, working under the auspices of the US energy department. He recently wrote a book called the Large Hadron Collider: an unusual story of the Higgs boson and other things that will amaze you .

In science with the Internet there are complex relationships: science moves forward by carefully and carefully evaluating data and theory, and this process can go on for years. And on the Internet, the audience’s ability to concentrate resembles Dory’s Disney fish from the cartoon “Finding Nemo” (and now “Finding Dory”) is a meme, here is a star photo ... Oh look, funny cat ...

Therefore, people who are interested in serious science should be wary of information posted on the Internet, claiming scientific research, radically changing the paradigm of science. A recent example is an article stating the possible discovery of the fifth fundamental interaction. If this were so, we would have to rewrite the textbooks.

As a physicist, I want to shed a disciplined scientific light on this statement.

Fifth interaction

So what is claimed?

In an article sent on arXiv on April 7, 2015, a group of Hungarian researchers described a study of the behavior of an intense proton beam on thin lithium targets. The detected collisions created excited nuclei of beryllium-8, which decayed into ordinary berrylium-8 and electron-positron pairs.



They stated that the data obtained by them cannot be explained by known physical phenomena in the Standard Model, which runs modern particle physics. But the explanation of these data was possible with the existence of a hitherto unknown particle with a mass of 17 million eV, which is 32.7 times as heavy as an electron, or 2% of the mass of a proton. Particles appearing at such energies, rather low by modern standards, are well studied. And it would be very unexpected if a new one was discovered there.

However, the measurements have moved peer review and were published on January 26, 2016 in the journal Physical Review Letters , one of the most prestigious journals in physics of the world. In this publication, the researchers and their research overcame an impressive obstacle.

Few people noticed this measurement until a group of theoretical physicists from the University of California, Irvine (UCI) paid attention to it. And as theorists usually do with controversial physical measurements, the team compared them with the existing work collected over the last hundred years to see if the new data are in line with the information already collected. In this case, they were compared with a dozen published studies.

They found that although the measurements did not conflict with previous studies, something was observed in them that had not previously been encountered - and something that could not be explained by the Standard Model.

New theoretical platform

To understand the Hungarian dimensions, this group of theorists from the UCI came up with a new theory.

This theory is very exotic. They began with a reasonable assumption that the new possible particle is not explained by the existing theory. This makes sense, since a possible new particle has a small mass, and if it were described by the known laws of physics, it would have been found earlier. If this particle obeys the new laws of physics, perhaps a new interaction is also present. Since physicists traditionally speak of four well-known fundamental interactions (gravity, electromagnetism, strong and weak), this new hypothetical interaction was called the “fifth”.

The history of the theories and discoveries of the fifth interaction is quite diverse, it goes back several decades, and within its framework new dimensions and ideas arose, then disappear. On the other hand, there are riddles that are not explained by ordinary physics — for example, dark matter. Although dark matter has always been modeled as the only form of a stable massive particle experiencing gravity and none of the other known forces, there is no reason why dark matter would not participate in such interactions in which ordinary matter does not participate. After all, ordinary matter is involved in interactions in which dark is not involved - so there is nothing stupid here.



There are many ideas about interactions that affect only dark matter, and all of them are generally called “ complex dark matter.”"One of the well-known ideas suggests the existence of a dark photon interacting with a dark charge, carried only by dark matter. This particle is a dark analog of a photon of ordinary matter, interacting with the known electric charge, but with one exception: some theories of complex dark matter confer dark photons in mass, in contrast to ordinary photons.

If dark photons exist, they can communicate with ordinary matter (and ordinary photons) and decay into electron-positron pairs, which the group ve Nger scientists. Since dark photons do not interact with ordinary electric charge, this connection can arise only through the quirks of quantum mechanics. But if scientists began to observe an increase in electron-positron pairs, this may mean that they are observing dark photons.

The Irvine group found a model that includes a “proto-phobic” particle, not excluded by early measurements, that can explain the Hungarian result. “Protophobic,” that is, “proton-avoiding” particles, rarely or almost never interact with protons, but can interact with neutrons (neutrophilic).

The particle proposed by the Irvine group participates in the fifth, unknown interaction, which manifests itself at a distance of 12 femtometers, or 12 times larger than the size of the proton. Particle protophobic and neutrophilic. The particle mass is 17 million eV and may decay into electron-positron pairs. In addition to explaining the Hungarian experiment, such a particle could explain some inconsistencies found in other experiments. The latter adds some weight to this idea.

A paradigm-changing interaction?

That's the way it is.

What could be true? Data is the main thing. Other experiments will be required to confirm or disprove the changes. All the rest does not matter. But it will take about a year, and it would be nice to come up with some idea during this time. The best way to assess the likelihood that a discovery will turn out to be real is to study the reputation of the researchers who participated in the experiment. This, of course, is a vulgar way to do science, but it can mute your expectations.

Let's start with the Irvine group. Many of them (especially managers) have a good reputation and are well-established experts in the field, and they have good jobs in their resumes. The age of the group is different, there are both elderly and young participants. I know some of them personally, two of them read the theoretical parts in the chapters of the book that I wrote to make sure that I didn’t say nonsense there (By the way, they didn’t find any mistakes, but they helped clarify some points). This explains my respect for the members of the Irvine group, although it may make me biased. I am pretty sure that their work was thorough and professional in comparing the new model with the existing data. They discovered a small and unexplored region of possible theories.

On the other hand, the theory itself is rather speculative and unlikely. This is not a sentence - this is what can be said about all theories. After all, the Standard Model, which controls particle physics, has been known for 50 years and is well studied. In addition, all new theories are speculative and unlikely, and most of them are incorrect. This is also not a sentence. There are many ways to add corrections to existing theories to explain new phenomena. And all can not be true. And sometimes none of the proposed theories is true.

However, it can be concluded, based on the reputation of the group members, that they came up with a new idea and compared it with all the data relevant to it. The fact that they published their model means that it passed their tests and remained a plausible, albeit unlikely, opportunity.

What about the Hungarian band? I don’t know any of them personally, but the article was published in Physical Review Letters - this is already a plus for them. However, this group published two previous works, in which similar anomalies were observed, including a possible particle weighing 12 million eV, and a particle weighing 14 million eV . Both works have been refuted by other experiments.

Further, the Hungarian group did not explain what caused the mistakes in the refuted works. Another bell is that the group rarely publishes data that does not contain anomalies. This is unlikely. In my research career, most publications have confirmed existing theories. Repetitive anomalies are very rare.

So what is the result? Should we rejoice at a new possible discovery? Well, of course, possible discoveries are always interesting. The standard model has stood the test of 50 years, but there are unexplained riddles, and the scientific community is always looking for discoveries pointing to new and unproven theories. But what are the chances that this dimension and theory will lead the scientific community to accept the existence of a fifth interaction with a range of 12 fm and a particle that is wary of protons? I think there is little chance. I am not optimistic about the idea.

Of course, an opinion is only an opinion, even if it is information. Other experiments will also look for dark photons, because even if the Hungarian measurements fail verification, the dark matter problem will exist. Many experiments in search of dark photons will study the same parameter space (energy, mass and decay regimes) in which, according to the statement of the Hungarian researchers, an anomaly was found. Soon, over the course of a year, we will find out whether this anomaly was a discovery or another glitch that temporarily stirred up the community in order to then be discarded after receiving more accurate data. But no matter how it ends, the result will be an improved science.