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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 | |
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| Preprint Link: | https://arxiv.org/abs/2112.04429v1 (pdf) |
| Date accepted: | 2025-03-19 |
| 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: |
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| 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:
Editorial decision:
For Journal SciPost Physics Proceedings: Publish
(status: Editorial decision fixed and (if required) accepted by authors)
Reports on this Submission
Strengths
1. The paper is on a topical subject and is of importance to experiments.
2. It uses a large number of inputs from diverse experimental sources of information.
3. It uses the power of analyticity and unitarity and the Omnes formalism suited for the problem at hand.
4. The results are of use for the BELLE experiment
Weaknesses
1. The subject is quite technical and is hard to summarize in a conference proceedings, but the author has done his best.
Report
The criteria are met and the paper may be published.
Recommendation
Publish (surpasses expectations and criteria for this Journal; among top 10%)
Report
This contribution represents an interesting (and updated) summary of the results in ref. [15], benefiting from later publications of the author, refs.[24], [27] and [28], yielding challenging predictions for the tau -> eta pi nu branching ratio for detection at Belle-II, which are based on a dispersive formulation of final state interactions that allows to relate these decays to γγ → ηπ
and to φ → γηπ, for which data exist. I would only give the author to correct a few typos before publishing it: 'Tony' -> 'Toni', 'where implemented'->'were implemented' and ' and idea proposed' ->' an idea proposed'.
Recommendation
Publish (surpasses expectations and criteria for this Journal; among top 10%)
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.
Recommendation
Publish (surpasses expectations and criteria for this Journal; among top 10%)