Lepton flavour violating top decays at the LHC

Abstract

We consider lepton-flavour violating decays of the top quark, mediated by 4-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–μ flavour change are more restrictive than on ℓ–τ ; nonetheless the top could decay to a (formula presented) with a branching ratio of order 10 -3. We estimate that the currently available LHC data (20 fb -1 at 8 TeV) could be sensitive to (formula presented), and we extrapolate that 100 fb -1 at 13 TeV could reach a sensitivity of ∼1 × 10 -5.