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Deriving experimental constraints on the scalar form factor in the second-class $τ\toηπν$ mode

by B. Moussallam

Submission summary

Authors (as registered SciPost users): Bachir Moussallam
Submission information
Preprint Link: https://arxiv.org/abs/2112.04429v1  (pdf)
Date submitted: 2021-12-09 14:50
Submitted by: Moussallam, Bachir
Submitted to: SciPost Physics Proceedings
Proceedings issue: 16th International Workshop on Tau Lepton Physics (TAU2021)
Ontological classification
Academic field: Physics
Specialties:
  • High-Energy Physics - Phenomenology
Approach: Theoretical

Abstract

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 can differ by one to two orders of magnitude. Here, an approach based on a systematic use of the property of analyticity of form factors and scattering amplitudes in QCD is discussed. In particular, we 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 have been performed by the Belle and KLOE collaborations.

Current status:
In voting

Reports on this Submission

Report #1 by Swagato Banerjee (Referee 1) on 2024-11-29 (Invited Report)

Report

The branching fraction for the second class decay mode tau- -> pi- eta nu is studied using an approach based on a systematic use of the property of analyticity of form factors and scattering amplitudes in QCD. The scalar form factor in the τ decay can be related to photon-photon scattering and radiative φ decay amplitudes for which precise experimental measurements have been performed by the Belle and KLOE collaborations. The result are expectation of branching fractions at the 10^-6 level, which makes the search for this decay mode at the Belle II expreiment very challenging. However, these new measurements should be able to rule out some of the theoretical models.

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