The LHCb collaboration at CERN has found that particles do not behave as they should, according to the main theory of particle physics – the Standard Model.
The Standard Model of particle physics predicts that b-quarks should decay equally into either muons or 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 and the Universities of Bristol and Cambridge analyzed the data to produce this result with financial support from the Science and Technology Council. 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 best theory of particle physics, describing 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 results of the experiment, our hearts really beat a little faster,” says Mitesh Patel, PhD, Physics Department 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).
The LHC is the world’s largest and most powerful particle collider – it accelerates subatomic particles to near the speed of light before colliding them against 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.
The new measurements call into question the laws of nature that apply equally to electrons and their heavier counterparts, the muons, with the exception of 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.
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 intriguing 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 standard of discovery is five standard deviations, which means that the probability that a 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, because our current understanding of the universe is in many ways untrue. Although 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.
The LHCb collaboration must now continue to validate its findings by collating and analyzing more data to see if there is evidence for some new phenomena. The LHCb experiment is expected to begin collecting new data next year after upgrading the detector.