Interplay of LFV and slepton mass splittings at the LHC as a probe of the SUSY seesaw

TL;DR

This paper investigates how a SUSY seesaw mechanism links high-energy slepton mass splittings observed at the LHC with low-energy lepton flavour violation signals, providing insights into the origin of LFV.

Contribution

It offers a systematic analysis connecting LHC slepton mass measurements with low-energy LFV observables within the SUSY seesaw framework, highlighting their combined potential to reveal LFV origins.

Findings

Slepton mass splittings can indicate non-universality or LFV.

Correlations between LHC and low-energy LFV observables are possible.

Analysis constrains SUSY seesaw parameters using combined data.

Abstract

We study the impact of a type-I SUSY seesaw concerning lepton flavour violation (LFV) both at low-energies and at the LHC. The study of the di-lepton invariant mass distribution at the LHC allows to reconstruct some of the masses of the different sparticles involved in a decay chain. In particular, the combination with other observables renders feasible the reconstruction of the masses of the intermediate sleptons involved in $ \chi_2^0\to \tilde \ell \,\ell \to \ell \,\ell\,\chi_1^0$ decays. Slepton mass splittings can be either interpreted as a signal of non-universality in the SUSY soft breaking-terms (signalling a deviation from constrained scenarios as the cMSSM) or as being due to the violation of lepton flavour. In the latter case, in addition to these high-energy processes, one expects further low-energy manifestations of LFV such as radiative and three-body lepton decays. Under the assumption of a type-I seesaw as the source of neutrino masses and mixings, all these LFV observables are related. Working in the framework of the cMSSM extended by three right-handed neutrino superfields, we conduct a systematic analysis addressing the simultaneous implications of the SUSY seesaw for both high- and low-energy lepton flavour violation. We discuss how the confrontation of slepton mass splittings as observed at the LHC and low-energy LFV observables may provide important information about the underlying mechanism of LFV.