Supersymmetry Without Prejudice at the LHC

TL;DR

This study assesses ATLAS detector's ability to discover supersymmetry across a broad, model-independent parameter space, demonstrating high potential for detection with current search strategies and identifying challenging scenarios.

Contribution

It evaluates the effectiveness of ATLAS SUSY searches in a comprehensive, model-independent MSSM subspace, confirming robustness and identifying limitations.

Findings

Almost all models with sparticle masses below 1 TeV are discoverable.

Reducing systematic errors from 50% to 20% significantly increases coverage.

The ATLAS search strategy is effective across a broad class of SUSY models.

Abstract

The discovery and exploration of Supersymmetry in a model-independent fashion will be a daunting task due to the large number of soft-breaking parameters in the MSSM. In this paper, we explore the capability of the ATLAS detector at the LHC ($\sqrt s=14$ TeV, 1 fb$^{-1}$) to find SUSY within the 19-dimensional pMSSM subspace of the MSSM using their standard transverse missing energy and long-lived particle searches that were essentially designed for mSUGRA. To this end, we employ a set of $\sim 71$k previously generated model points in the 19-dimensional parameter space that satisfy all of the existing experimental and theoretical constraints. Employing ATLAS-generated SM backgrounds and following their approach in each of 11 missing energy analyses as closely as possible, we explore all of these $71$k model points for a possible SUSY signal. To test our analysis procedure, we first verify that we faithfully reproduce the published ATLAS results for the signal distributions for their benchmark mSUGRA model points. We then show that, requiring all sparticle masses to lie below 1(3) TeV, almost all(two-thirds) of the pMSSM model points are discovered with a significance $S>5$ in at least one of these 11 analyses assuming a 50\% systematic error on the SM background. If this systematic error can be reduced to only 20\% then this parameter space coverage is increased. These results are indicative that the ATLAS SUSY search strategy is robust under a broad class of Supersymmetric models. We then explore in detail the properties of the kinematically accessible model points which remain unobservable by these search analyses in order to ascertain problematic cases which may arise in general SUSY searches.