Semileptonic decays of heavy mesons with artificial neural networks

Abstract

Experimental checks of the second row unitarity of the Cabibbo-Kobayashi-Maskawa (CKM) matrix involve extractions of the matrix element V cd , which may be obtained from semileptonic decay rates of D to π. These decay rates are proportional to hadronic form factors which parametrize how the quark c → d transition is realized in D → π meson decays. The form factors cannot yet be analytically computed over the whole range of available momentum transfer q 2 , but can be parametrized with a varying degree of model dependency. We propose analysis of the form factor shapes using a system of artificial neural networks trained from experimental pseudodata and averaged together to predict their shapes with a prescribed uncertainty. We comment on the parameters of several commonly-used model parametrizations of semileptonic form factors. We extract shape parameters and use unitarity to bound the form factor at a given q 2 , which then allows us to bound the CKM matrix element jV cd j.