Felix Metzner

15 February 2019
KEK-FF 2019

Abstract: We present the results of an improved search for the rare B meson decays B+ -> l+ nu_l gamma (with l = e, mu) based on the full data set of 711 fb^-1 B\bar{B} events recorded by the Belle experiment. Candidates for the signal B meson are reconstructed by combining a photon with an energy larger than 1 GeV and an electron or muon. Utilizing a novel algorithm for the full reconstruction of the second B meson of the event in hadronic decay modes, further discriminating variables such as the squared missing mass, which is fitted to infer on the number of signal events, are extracted. This exclusive tagging algorithm is trained to recognize the signature of the signal decays and results in a significant enhancement of the reconstruction efficiency. The yield of the most prominent background processes, B+ -> pi0 l+ nu, is measured simultaneously to the number of signal events and used for the validation of the tagging algorithm as well as to allow for a determination of the first inverse momentum of the light-cone distribution amplitude of the B meson independent of the CKM matrix element V_ub. This talk presents the described search and the prospects for the decays B -> l nu (gamma) with Belle II.

Note: 30 min