A cornerstone of the Standard Model (SM) is the universality of the electroweak couplings to the three lepton families. This results in an accidental lepton flavor symmetry that is broken in the SM only due to the different masses of the charged leptons. However, since 2012, a series of measurements of decays involving tree-level b → cτν and loop-level b → sℓℓ transitions (the so-called "B anomalies") repeatedly hinted at the possibility that lepton flavor universality (LFU) may be, in fact, violated. Then, in December 2022 LHCb reported that the deviations in their measurements of b → sℓℓ LFU ratios were due to previously unaccounted-for background contributions. In this talk I will report the latest status of the anomalies that went away (RK and RK*), and the ones that remain (RD, RD*, and the branching fraction/angular distributions in b → sμμ).
About the speaker: Manuel Franco Sevilla is an assistant professor at the University of Maryland working on the LHCb experiment. His research currently focuses on measurements that test lepton universality. Additionally, Franco Sevilla works on the Upstream Tracker (UT), a new silicon tracker that was just installed as part of LHCb's Upgrade I. He obtained his PhD at Stanford University working on the BaBar experiment where he saw the first hints of Lepton Flavor Universality violation in RD and RD*, and then he went on to the University of California Santa Barbara to work as a postdoc at the CMS experiment searching for Supersymmetry and developing electronics for the Cathode Strip Chambers.