Top-squark in natural SUSY under current LHC run-2 data

TL;DR

This paper analyzes recent LHC-13 TeV data to establish lower mass bounds on top-squarks in natural supersymmetry, highlighting the complementarity of various search strategies depending on stop and higgsino masses.

Contribution

It provides a comprehensive recasting of multiple LHC search channels to determine the most effective bounds on top-squark masses in different natural SUSY scenarios.

Findings

Lower stop mass bound is 320 GeV in compressed stop-higgsino scenario.

Bounds are 765 GeV for higgsinos lighter than 300 GeV.

Bounds are 860 GeV for higgsinos lighter than 100 GeV.

Abstract

We utilize the recent LHC-13 TeV data to study the lower mass bound on top-squark (stop) in natural supersymmetry. We recast the LHC sparticle inclusive search of $(\ge 1){\rm jets} + E^{miss}_T$ with $\alpha_T$ variable, the direct stop pair search (1-lepton channel and all-hadronic channel) and the monojet analyses. We find that these searches are complementary depending on stop and higgsino masses: for a heavy stop the all-hadronic stop pair search provides the strongest bound, for an intermediate stop the inclusive SUSY analysis with $\alpha_T$ variable is most efficient, while for a compressed stop-higgsino scenario the monojet search plays the key role. Finally, the lower mass bound on a stop is: (i) 320 GeV for compressed stop-higgsino scenario (mass splitting less than 20 GeV); (ii) 765 (860) GeV for higgsinos lighter than 300 (100) GeV.