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Description
In the Standard Model of particle physics, the electroweak couplings of leptons to gauge bosons are independent of their flavour. This incidental symmetry, known as Lepton Universality, has been extensively tested in the gauge sector and in transitions between light quarks but has never been established in decays of heavy quarks.
Recent measurements of B-meson decays hint at deviations from Lepton Universality in two classes of transitions: tree-mediated b→cln processes and loop-mediated b→sll decays. Measurements of highly suppressed Flavour-Changing Neutral-Current b→sll transitions exhibit a difference involving muons and electrons, while measurements of more frequent tree-level processes manifest a difference between muons and taus. These two classes of decays present very different challenges, both experimentally and theoretically.
The seminar will review the status of the present tests of Lepton Universality in b-quark decays and discuss the future of these so called “flavour anomalies” in the context of the quest for physics Beyond the Standard Model.
