Momentum reconstruction at the LHC for probing CP-violation in the stop sector

TL;DR

This paper proposes a method to reconstruct momenta in SUSY stop decay chains at the LHC to enhance the detection of CP-violation effects, which are otherwise diluted by boosts, enabling potential observation with sufficient data.

Contribution

It introduces a momentum reconstruction technique for decay chains with missing energy, improving CP-violation sensitivity in SUSY stop searches at the LHC.

Findings

Reconstruction can recover diluted CP asymmetries.

Potential for 3-sigma CP-violation observation with 500 fb^(-1).

Identifies parameter space regions suitable for detection.

Abstract

We study the potential to observe CP-violating effects in SUSY stop cascade decay chains at the LHC. Asymmetries composed by triple products of momenta of the final state particles are sensitive to CP-violating effects. Due to large boosts that dilute the asymmetries, these can be difficult to observe. If all particle masses in a cascade decay are known, it may be possible to reconstruct all momenta in the decay chains on an event-by-event basis even when we have missing momentum due to a stable LSP. After the reconstruction, the non-diluted CP-violating signal can be recovered and gets significantly enhanced so that an observation may become feasible. A fully hadronic study has been completed to define the areas of the mSUGRA parameter space that may yield a 3-sigma observation with 500 fb^(-1) at the LHC.