The Simplest B Decay, Precisely

by Claudia Cornella

Monday 23 Feb 2026, 14:00 → 15:00 Europe/Zurich

4/3-006 - TH Conference Room (CERN)

The exclusive leptonic decay $B \to l \nu$ is arguably the simplest $B$-meson decay, but it becomes surprisingly intricate once QED corrections are included. The latter bring in several distinct scales, and separating point-like from structure-dependent effects requires a sequence of effective theories, ranging from HQET and SCET down to a hadronic description at low energies. In this talk I will sketch the derivation of a QCD$\times$QED factorization theorem for $B \to \mu \nu (\gamma)$, explain the EFT setup used to disentangle virtual and real radiation, and present our phenomenological predictions.