Lepton Flavour Violating top decays at the LHC

TL;DR

This paper investigates lepton flavor violating top quark decays mediated by four-fermion operators, analyzing constraints from existing data and estimating the LHC's potential to detect such rare decays with future datasets.

Contribution

It provides a comprehensive analysis of constraints on lepton flavor violating top decays and estimates the LHC's sensitivity to these processes with current and future data.

Findings

Constraints on e-mu flavor violation are more restrictive than l-tau.

Top quark could decay to jet + e mu with a branching ratio of about 10^{-3}.

LHC at 8 TeV could detect branching ratios around 6×10^{-5}.

Abstract

We consider lepton flavour violating decays of the top quark, mediated by four-fermion operators. We compile constraints on a complete set of SU(3)*U(1)-invariant operators, arising from their loop contributions to rare decays and from HERA's single top search. The bounds on e-mu flavour change are more restrictive than l-tau; nonetheless the top could decay to a jet $+ e \bar{\mu}$ with a branching ratio of order $10^{-3}$. We estimate that the currently available LHC data (20 inverse-fb at 8 TeV) could be sensitive to $BR(t \to e \bar{\mu}$+ jet) $ \sim 6\times 10^{-5}$, and extrapolate that 100 inverse-fb at 13 TeV could reach a sensitivity of $ \sim 1 \times 10^{-5}$.