Probing CP Violation with and without Momentum Reconstruction at the LHC

TL;DR

This paper explores methods to detect CP violation in supersymmetric particle decay chains at the LHC, emphasizing the importance of event reconstruction and analyzing the impact of experimental challenges.

Contribution

It introduces a technique for event-by-event decay chain reconstruction in complex SUSY decays, enhancing CP violation detection prospects at the LHC.

Findings

CP violation could be observed with 300 fb$^{-1}$ of data.

Event reconstruction improves sensitivity to CP-violating effects.

Analysis accounts for detector effects and backgrounds.

Abstract

We study the potential to observe CP-violating effects in SUSY cascade decay chains at the LHC. We consider squark and gluino production followed by subsequent decays into neutralinos with a three-body leptonic decay in the final step. Asymmetries composed by triple products of momenta of the final state particles are sensitive to CP-violating effects. Due to large boosts these asymmetries can be difficult to observe at a hadron collider. We show that using all available kinematic information one can reconstruct the decay chains on an event-by-event basis even in the case of 3-body decays, neutrinos and LSPs in the final state. We also discuss the most important experimental effects like major backgrounds and momentum smearing due to finite detector resolution. We show that with 300 fb$^{-1}$ of collected data, CP violation may be discovered at the LHC for a wide range of the phase of the bino mass parameter $M_1$.