Lepton flavour violation: physics potential of a Linear Collider

TL;DR

This paper assesses the potential of a Linear Collider to detect lepton flavor violation signals predicted by a supersymmetric seesaw model, showing promising prospects for observing such rare events amidst backgrounds.

Contribution

It evaluates the observability of seesaw-induced lepton flavor violating processes at a Linear Collider, considering recent experimental bounds and beam polarization effects.

Findings

Signal detection is feasible over large parameter regions.

Electron-electron collisions provide a clear probe with minimal background.

Polarization enhances the sensitivity to flavor violating signals.

Abstract

We revisit the potential of a Linear Collider concerning the study of lepton flavour violation, in view of new LHC bounds and of the (very) recent developments in lepton physics. Working in the framework of a type I supersymmetric seesaw, we evaluate the prospects of observing seesaw-induced lepton flavour violating final states of the type e \mu + missing energy, arising from e+ e- and e- e- collisions. In both cases we address the potential background from standard model and supersymmetric charged currents. We also explore the possibility of electron and positron beam polarisation. The statistical significance of the signal, even in the absence of kinematical and/or detector cuts, renders the observation of such flavour violating events feasible over large regions of the parameter space. We further consider the \mu-\mu- + E^T_miss final state in the e- e- beam option finding that, due to a very suppressed background, this process turns out to be a truly clear probe of a supersymmetric seesaw, assuming the latter to be the unique source of lepton flavour violation.