Search for top squarks in final states with one isolated lepton, jets, and missing transverse momentum in s√=13 TeV pp collisions with the ATLAS detector

H. WAHLBERG Y ATLAS COLLABORATION

PHYSICAL REVIEW D

AMER PHYSICAL SOC

Lugar: New York; Año: 2016

1550-7998

The results of a search for the stop, the supersymmetric partner of the top quark, in finalstates with one isolated electron or muon, jets, and missing transverse momentum arereported. The search uses the 2015 LHC pp collision data at a center-of-mass energy of√s = 13 TeV recorded by the ATLAS detector and corresponding to an integrated lumi-nosity of 3.2 fb −1 . The analysis targets two types of signal models: gluino-mediated pairproduction of stops with a nearly mass-degenerate stop and neutralino; and direct pairproduction of stops, decaying to the top quark and the lightest neutralino. The experi-mental signature in both signal scenarios is similar to that of a top quark pair producedin association with large missing transverse momentum. No significant excess over theStandard Model background prediction is observed, and exclusion limits on gluino andstop masses are set at 95% confidence level. The results extend the LHC Run-1 exclu-sion limit on the gluino mass up to 1460 GeV in the gluino-mediated scenario in the highgluino and low stop mass region, and add an excluded stop mass region from 745 to780 GeV for the direct stop model with a massless lightest neutralino. The results arealso reinterpreted to set exclusion limits in a model of vector-like top quarks.