….so far the standard model has been very resilient, successfully able to explain everything that the experimental physicists managed to throw at it. That might be about to change. Two collaborations of scientists working at the LHC – one using the Compact Muon Solenoid detector and another carrying out the LHC beauty experiment – at the particle physics lab CERN near Geneva measured the decays of so-called B mesons. B mesons are weird particles made up of a specific quark and an antiquark. They looked at two different kinds of particle: a “neutral” B meson and a “strange” B meson.
All B mesons are short-lived and decay spontaneously into a bunch of other mesons. But this study specifically looked at the decays of B mesons into pairs of so-called muons, which are heavier versions of electrons, and their antiparticles. These decays are particularly interesting because their probabilities can be calculated within the standard model with little ambiguity and high precision. From the experimental point of view, the muons are relatively easy to detect and can be measured with high accuracy.
Starting point for a theory of everything – So, according to the standard model, on average about four of every billion strange B-mesons decay into the muon-antimuon pair (instead of into other particles). For the Neutral B-meson this number is even smaller, about one in ten billion. These are very small numbers indeed and explain why past experiments have failed to detect them.But the new experiments have been able to observe these decays, and to measure their probabilities. They show that while the strange B-meson decays into muons at the same rate that the standard model predicts, the neutral B-meson does so about four times more often than predicted (although the accuracy here was somewhat lower). Source: New Discovery in Particle Physics Raises Hope for a “Theory of Everything”