![]() "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. Such as IceCube-Gen2, Baikal-GVD, KM3NeT, P-ONE, and TAMBO.Previous studies of these decays had hinted at intriguing tensions with the theoretical predictions, potentially due to the effects of new particles or forces. Improvement in the sensitivity due to the next-generation neutrino telescopes That, already today, the IceCube neutrino telescope demonstrates potential toĬonstrain flavor-dependent long-range interactions significantly better thanĮxisting constraints, motivating further analysis. ![]() That could be placed on the coupling strength of these interactions. Neutrino telescopes and of oscillation experiments to estimate the constraints We leverage the present-day and future sensitivity of high-energy Ultra-light, lighter than $10^$ eV, the interaction range is ultra-long,įrom km to Gpc, allowing vast numbers of electrons and neutrons in celestialīodies and the cosmological matter distribution to contribute to this new Because we consider mediators of these new interactions to be Of the diffuse flux of high-energy astrophysical neutrinos, with TeV-PeVĮnergies, i.e., the proportion of $\nu_e$, $\nu_\mu$, and $\nu_\tau$ in theįlux. We revisit, revamp, and improve theĬonstraints on these interactions that can be placed via the flavor composition Introduce a new matter potential sourced by electrons and neutrons, potentially Symmetries, specifically $L_e-L_\mu$, $L_e-L_\tau$, and $L_\mu-L_\tau$, that Interactions generated by the anomaly-free, gauged, abelian lepton-number Download a PDF of the paper titled Present and future constraints on flavor-dependent long-range interactions of high-energy astrophysical neutrinos, by Sanjib Kumar Agarwalla and 3 other authors Download PDF Abstract: The discovery of new, flavor-dependent neutrino interactions would provideĬompelling evidence of physics beyond the Standard Model.
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