Effective-field theory analysis of the $\tau^{-}\to K^{-}(\eta^{(\prime)},K^{0}) \nu_{\tau}$ decays

TL;DR

This paper investigates tau decays into specific mesons using an effective field theory framework, analyzing decay spectra, asymmetries, and setting bounds on new physics couplings based on experimental data.

Contribution

It introduces a comprehensive effective field theory analysis of tau decays with detailed phenomenological observables and sets bounds on non-standard scalar and tensor couplings.

Findings

Bounds on scalar and tensor couplings consistent with previous analyses.

Decay spectra and asymmetries sensitive to non-standard interactions.

Standard Model form factors constrained by chiral symmetry and QCD data.

Abstract

We analyze the decays $\tau^-\to K^-(\eta^{(\prime)},K^0) \nu_\tau$ within an effective field theory that includes the most general interactions between Standard Model fields up to dimension six, assuming left-handed neutrinos. In particular, we examine different interesting phenomenological observables i.e. decay spectra and branching ratio, Dalitz plot distributions and the forward-backward asymmetry, to explore the sensitivity of the corresponding decays to the effects of non-standard interactions. A controlled theoretical input on the Standard Model hadronic form factors, based on chiral symmetry, dispersion relations, data and asymptotic QCD properties, has allowed us to set bounds on the New Physics scalar and tensor effective couplings using the measured branching ratios. These are found to be in line with the findings of our series of previous analyses of two-meson tau decays and less precise than the constraints obtained from semileptonic kaon decays. In order to set stringent limits on these couplings, we will use all available experimental data of all possible di-meson tau decays. This is our next step plan, that we hope to be of interest for future experimental analyses of these decays.