September 27, 2021 to October 1, 2021
Indiana University
America/Indiana/Indianapolis timezone

Deriving experimental constraints on the scalar form factor in the second-class 𝜏→𝜂𝜋𝜈 mode

Sep 29, 2021, 9:05 AM
Virtual (Indiana University)


Indiana University

Oral contribution Tau2021 Abstracts Session 3: Exclusive and inclusive hadronic tau decays


Bachir Moussallam (Universite Paris-Saclay)


The rare second-class decay mode of the $\tau$ into $\eta\pi\nu$ could be
observed for the first time at Belle II. It is important to try to derive
a reliable evaluation of the branching fraction and of the energy
distribution of this mode within the standard-model. Many predictions
exist already in the literature which, unfortunately, can differ by one to
two orders of magnitude. In this talk I discuss an approach based on a
systematic use of the property of analyticity (of form factors and
amplitudes) in QCD. In particular, I will show that the scalar form factor
in the $\tau$ decay can be related to photon-photon scattering and
radiative $\phi$ decay amplitudes for which precise experimental
measurements (by Belle and Kloe) exist.

Primary author

Bachir Moussallam (Universite Paris-Saclay)

Presentation materials