Measuring Smuon-Selectron Mass Splitting at the LHC and Patterns of Supersymmetry Breaking

TL;DR

This paper explores how the LHC can measure tiny differences in selectron and smuon masses through decay edge analysis, providing insights into high-scale supersymmetry breaking.

Contribution

It demonstrates the LHC's sensitivity to small mass splittings and highlights the importance of edge splitting measurements for understanding SUSY breaking.

Findings

LHC can constrain selectron-smuon mass splitting to ~10^{-4} with 30 fb^{-1}.

Edge splittings can be significantly larger than mass splittings due to SUSY effects.

Edge splitting measurements can discriminate between different SUSY breaking models.

Abstract

With sufficient data, Large Hadron Collider (LHC) experiments can constrain the selectron-smuon mass splitting through differences in the di-electron and di-muon edges from supersymmetry (SUSY) cascade decays. We study the sensitivity of the LHC to this mass splitting, which within mSUGRA may be constrained down to O(10^{-4}) for 30 fb^{-1} of integrated luminosity. Over substantial regions of SUSY breaking parameter space the fractional edge splitting can be significantly enhanced over the fractional mass splitting. Within models where the selectron and smuon are constrained to be universal at a high scale, edge splittings up to a few percent may be induced by renormalisation group effects and may be significantly discriminated from zero. The edge splitting provides important information about high-scale SUSY breaking terms and should be included in any fit of LHC data to high-scale models.