NePSi 23

Lattice determination of the spectral function for Ds→ℓνℓγ∗ decays

16 Feb 2023, 11:50

30m

Aula Magna - Dipartimento di Fisica (Università di Pisa - Dipartimento di Fisica)

Senior Session

Speaker

Giuseppe Gagliardi (Istituto Nazionale di Fisica Nucleare)

Description

We discuss a novel approach, based on spectral reconstruction techniques, which circumvents the well-known problem of the analytic continuation from Minkowskian to Euclidean time for hadronic processes above kinematical thresholds. The approach is discussed for the specific case of the radiative decays of pseudoscalar mesons $P\to \ell {\nu }_{\ell }{\gamma }^{}$, where ${\gamma }^{}$ is a virtual photon.
These processes, which give access to the rare decays $P\to \ell {\nu }_{\ell }{\overline{\ell }}^{\prime }{\ell }^{\prime }$, are notoriously difficult to study on
the lattice due to the presence of intermediate states which hinder the analytic continuation to Euclidean time when the photon off-shellness $\sqrt{k^2}$ is larger than the invariant mass of the lightest intermediate state. We apply the new spectral reconstruction method to the decay $D_s\to \ell {\nu }_{\ell }{\gamma }^{\ast }$ and present some preliminary results.

Presentation materials

NePSI_talk_Gagliardi.pdf