QED effects in exclusive B decays and light-cone distribution amplitudes

Tuesday, 28 November 2023 at 11:30

The exponentiation of soft photon radiation is a classic result of QED, but for QED effects on objects with structure a more general approach is required. In this seminar I discuss how modern methods of effective field theory and factorization (more familiar for the strong interaction) result in a systematic treatment of QED effects in decays of B mesons to a lepton pair, or a pair of light mesons, including the summation of large logarithms. On top of adding precision, QED offers surprises: for B -> mu mu, the QED correction is enhanced in heavy-quark power counting, and reveals that the process is no longer a pure annihilation decay. The presence of QED also modifies the definition and properties of light-cone distribution amplitudes of light mesons and B mesons in an interesting way.