15.01.2024 / 13:15 - 14:15 / Zeuthen, Online

Lattice seminar

Spectral-function determination of complex electroweak amplitudes with lattice QCD (8/12)

Dr. Giuseppe Gagliardi (INFN - Roma 3)

We discuss a novel approach, based on spectral density reconstruction techniques, to circumvent the well-known problem of analytic continuation from Minkowskian to Euclidean time of electroweak amplitudes above kinematic thresholds. The method can be used to compute any hadron-to-vacuum QCD matrix element involving two external currents and, in its basic form, relies on the use of Feynman's prescription to regularize the problem. The approach is discussed in the specific case of radiative decays of pseudoscalar mesons , where is a virtual photon. These processes, which give access to the rare decays, are notoriously difficult to study on the lattice because of the presence of intermediate states that hinder analytical continuation when the off-shell invariant mass of the photon is greater than that of the lightest intermediate state. We present the numerical results of our study in the case .

Mehr Informationen: https://indico.desy.de/category/873/