Experiment at the LHC showed a deviation of the behavior of b-quarks from the Standard Model

The Standard Model of Particle Physics predicts b-quarks should decay equally

either into muons or into electrons.However, the new result at LHCb suggests that this may not be the case. This indicates the existence of new particles or interactions that are not explained by the Standard Model.

Physicists from Imperial College London andThe universities of Bristol and Cambridge analyzed the data to arrive at this result with financial support from the Council for Science and Technology. The result was announced today at the Moriond Electroweak Physics conference and published as a preprint.

Outside the standard model

The standard model is currently the bestthe theory of particle physics, which describes all the known fundamental particles that make up our universe, and the forces with which they interact. The problem is that the Standard Model cannot explain some of the deepest mysteries of modern physics, including what dark matter is made of and the imbalance between matter and antimatter in the universe.

Therefore, the researchers looked for particles that behave differently than one would expect in the Standard Model. The goal is to explain some of these mysteries.

“When we first saw the resultsexperiment, our hearts really beat a little faster, - says Dr. Mitesh Patel from the Department of Physics at Imperial College London. “Of course, it’s too early to tell if this is really a departure from the Standard Model. And yet these results are the most exciting thing I've done in 20 years in this field. "

Building blocks of nature

The results the physicist says come from the LHCb experiment, one of four huge particle detectors at CERN's Large Hadron Collider (LHC).

LHC - the largest and most powerful in the worldparticle collider - it accelerates subatomic particles to near the speed of light before colliding them into each other. These collisions produce a burst of new particles that physicists then record and study to better understand the basic building blocks of nature.

New dimensions challenge lawsnature, which treat electrons and their heavier counterparts, muons, in the same way, except for small differences due to their different masses. According to the Standard Model, muons and electrons interact with all forces in the same way, so the b quarks created in LHCb should decay into muons as often as into electrons.

A very rare decay of a beautiful meson with the participation of an electron and a positron is observed at LHCb. Credit: Imperial College London.

But new measurements suggest decay occurs at different rates. This may indicate previously unseen particles tipping the scales away from muons.

“The result of the experiment offers an intriguinga hint of a new fundamental particle or force that “works” in a completely different way than anything known to science, ”explains Daniel Moyes, Ph.D. "If confirmed by further measurements, it will have a profound impact on our understanding of nature at the most fundamental level."

Opening gold standard

In particle physics, the gold standarddiscoveries are five standard deviations, which means that the probability that the result will turn out to be random is 1 in 3.5 million. The new result is three deviations so far. There is a probability that the measurement is a statistical coincidence, is 1 in 1000. Therefore, it is too early to draw any firm conclusions.

“There must be new, different particles, becauseour current understanding of the universe is in many ways untrue. While we need to wait for confirmation of the results, I hope that one day we can look back at this as a turning point in physics, ”concludes Dr. Michael McCann.

Now the LHCb collaboration must continuechecking their results by collating and analyzing more data to see if there is still evidence for some new phenomena. The LHCb experiment is expected to begin collecting new data next year after upgrading the detector.

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b-quark - a quark with charge −⅓ e, belonging tothird generation. It is a lighter member of the third-generation weak quark doublet, which also includes a much heavier t-quark. It has a mass of 4.2-4.7 GeV, almost 5 times heavier than a nucleon. The b-quark lifetime is about 10 около² s.

LHCb is the smallest of the four majordetectors at the LHC collider in the European organization for nuclear research CERN in Geneva. The experiment is carried out to investigate the asymmetry of matter and antimatter in b-quark interactions.