Study of radiative leptonic decays from first principles

by Davide Giusti (Forschungszentrum Jülich)

Tuesday Nov 19, 2024, 4:00 PM → 6:00 PM Europe/Zurich

4/2-037 - TH meeting room (CERN)

In the region of hard photon energies, radiative leptonic decays represent important probes of the internal structure of hadrons. Moreover, radiative decays can provide independent determinations of Cabibbo-Kobayashi-Maskawa matrix elements with respect to purely leptonic or semileptonic channels. Prospects for a precise determination of leptonic decay rates with emission of a hard photon are particularly interesting, especially for the decays of heavy mesons for which currently only model-dependent predictions, based on QCD factorization and sum rules, are available to compare with existing experimental data. We present a non-perturbative lattice calculation of the structure-dependent form factors which contribute to the amplitudes for the radiative decays $H \to \ell \nu_\ell \gamma$, where H is a charged pseudoscalar meson. With moderate statistics, thanks to the use of improved estimators, we are able to provide rather precise, first-principles results for the form factors in the full kinematical (photon-energy) range. Our continuum-extrapolated lattice determinations may then be employed to compute the differential decay rate and the corresponding branching fraction and make comparisons with existing experimental data.

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