Improving the sensitivity of stop searches with on-shell constrained invariant mass variables

TL;DR

This paper introduces on-shell constrained M_2 variables to improve the sensitivity of stop searches at the LHC, especially in regions where current analyses are less effective, aiding the discovery of new physics.

Contribution

The paper demonstrates the effectiveness of on-shell constrained M_2 variables in enhancing stop search sensitivity, addressing gaps in existing LHC analyses.

Findings

M_2 variables improve detection sensitivity for light stops.

Application to benchmark points shows increased reach.

Realistic effects like detector noise are considered.

Abstract

The search for light stops is of paramount importance, both in general as a promising path to the discovery of beyond the standard model physics and more specifically as a way of evaluating the success of the naturalness paradigm. While the LHC experiments have ruled out much of the relevant parameter space, there are "stop gaps", i.e., values of sparticle masses for which existing LHC analyses have relatively little sensitivity to light stops. We point out that techniques involving on-shell constrained M_2 variables can do much to enhance sensitivity in this region and hence help close the stop gaps. We demonstrate the use of these variables for several benchmark points and describe the effect of realistic complications, such as detector effects and combinatorial backgrounds, in order to provide a useful toolkit for light stop searches in particular, and new physics searches at the LHC in general.