Search for Tau Flavour Violation at the LHC

TL;DR

This paper investigates the potential for detecting tau lepton flavor violation in supersymmetric particle decays at the LHC, considering neutrino data, theoretical models, and experimental constraints.

Contribution

It analyzes the conditions under which tau flavor violation could be observed in supersymmetric decays within CMSSM and SU(5) models, including simulation of signals and decay channels.

Findings

Tau flavor-violating decays may be detectable if branching ratios exceed 10%

Possible compatibility with existing tau to mu gamma decay limits in certain models

Signals from hadronic tau decays could be observed with current LHC capabilities

Abstract

We explore the prospects for searches at the LHC for sparticle decays that violate $\tau$ lepton number, in the light of neutrino oscillation data and the seesaw model for neutrino masses and mixing. We analyse the theoretical and phenomenological conditions required for tau flavour violation to be observable in \chi_2 \to \chi + \tau^\pm \mu^\mp decays, for cosmologically interesting values of the relic neutralino LSP density. We study the relevant supersymmetric parameter space in the context of the Constrained Minimal Supersymmetric Extension of the Standard Model (CMSSM) and in SU(5) extensions of the theory. We pay particular attention to the possible signals from hadronic tau decays, that we analyse using PYTHIA event simulation. We find that a signal for \tau flavour-violating \chi_2 decays may be observable if the branching ratio exceeds about 10%. This may be compatible with the existing upper limit on \tau \to \mu \gamma decays if there is mixing between right-handed sleptons, as could be induced in non-minimal SU(5) GUTs.