LEPTON FLAVORS FULL
"The results shown today are the product of a comprehensive study of the two main modes using our full data sample and applying new, more robust techniques. "Measurements of the ratios of rare B-meson decays to electrons and muons have generated much interest in recent years because they are theoretically 'clean' and show consistency with a pattern of anomalies seen in other flavor processes," explains LHCb spokesperson Chris Parkes of the University of Manchester and CERN. The results, which supersede previous comparisons, are in excellent agreement with the principle of lepton flavor universality. In addition, the two decay modes are measured in two different mass regions, thus yielding four independent comparisons of the decays. It considers two different B-meson decay modes simultaneously for the first time and provides better control of the background processes that can mimic the decays of B-mesons to electrons. The new LHCb analysis, which has been ongoing for the past five years, is more comprehensive. But the LHCb results hinted that B mesons decay into muons at a lower rate than predicted, as indicated by the results' statistical significance of 3.1 standard deviations from the Standard Model prediction. According to the theory, decays involving muons and electrons should occur at the same rate, once differences in the leptons' masses are accounted for. Interest in the "flavor anomalies" peaked in March 2021, when LHCb presented new results comparing the rates at which certain B mesons, composite particles that contain beauty quarks, decay into muons and electrons. have suggested that this might not be the case, generating cautious excitement among physicists that a more fundamental theory-perhaps one that sheds light on the Standard Model's mysterious flavor structure-might reveal itself at the LHC. In recent years, however, an accumulation of results from LHCb and experiments in Japan and the U.S. Lepton flavor universality states that the fundamental forces are blind to the generation to which a lepton belongs.
The results of the improved and wider-reaching analysis based on the full LHC dataset collected by the experiment during Run 1 and Run 2, which were presented at a seminar at CERN held this morning, are in line with the Standard Model expectation.Ī central mystery of particle physics is why the 12 elementary quarks and leptons are arranged in pairs across three generations that are identical in all but mass, with ordinary matter comprising particles from the first, lightest generation.
No commercial reproduction, distribution, display or performance rights in this work are provided.Previous studies of these decays had hinted at intriguing tensions with the theoretical predictions, potentially due to the effects of new particles or forces. The discussion here concentrates on current and future probes of this apparent law of Nature via searches for neutrinoless double beta decay, which is also the most sensitive probe of the potential Majorana nature of neutrinos.Īndré de Gouvêa, Petr Vogel, Lepton flavor and number conservation, and physics beyond the standard model, Progress in Particle and Nuclear Physics, Volume 71, July 2013, Pages 75-92, ISSN 0146-6410. In the second part, the status of the conservation of total lepton number is discussed. The discussion concentrates mostly on rare processes involving muons and electrons. In the first part, several aspects of charged-lepton flavor violation are discussed, especially its sensitivity to new particles and interactions beyond the standard model of particle physics. Here, the physics associated with searches for the violation of lepton-flavor conservation in charged-lepton processes and the violation of lepton-number conservation in nuclear physics processes is summarized. More experimental data are needed to constrain and guide possible generalizations of the standard model of particle physics, and reveal the mechanism behind nonzero neutrino masses. The physics responsible for neutrino masses and lepton mixing remains unknown.
0 kommentar(er)
