Search for new physics with the MT2 variable in all-jets final states produced in pp collisions at sqrt(s) = 13 TeV

TL;DR

This paper reports a search for new physics using the MT2 variable in all-jets final states from proton-proton collisions at 13 TeV, setting limits on supersymmetric particle masses with no significant deviations from the standard model observed.

Contribution

It introduces a search strategy based on the MT2 variable in all-jets events and provides new exclusion limits on gluino and squark masses in supersymmetry models.

Findings

No significant excess over standard model backgrounds.

Gluino masses up to 1750 GeV are excluded.

Squark masses up to 880 GeV are excluded.

Abstract

A search for new physics is performed using events that contain one or more jets, no isolated leptons, and a large transverse momentum imbalance, as measured through the MT2 variable, which is an extension of the transverse mass in events with two invisible particles. The results are based on a sample of proton-proton collisions collected at a center-of-mass energy of 13 TeV with the CMS detector at the LHC, and that corresponds to an integrated luminosity of 2.3 inverse femtobarns. The observed event yields in the data are consistent with predictions for the standard model backgrounds. The results are interpreted using simplified models of supersymmetry and are expressed in terms of limits on the masses of potential new colored particles. Assuming that the lightest neutralino is stable and has a mass less than about 500 GeV, gluino masses up to 1550-1750 GeV are excluded at 95% confidence level, depending on the gluino decay mechanism. For the scenario of direct production of squark-antisquark pairs, top squarks with masses up to 800 GeV are excluded, assuming a 100% branching fraction for the decay to a top quark and neutralino. Similarly, bottom squark masses are excluded up to 880 GeV, and masses of light-flavor squarks are excluded up to 600-1260 GeV, depending on the degree of degeneracy of the squark masses.