Abstract

A search for supersymmetry is presented based on events with at least one photon, jets, and large missing transverse momentum produced in proton–proton collisions at a center-of-mass energy of 13,text {Te}text {V}. The data correspond to an integrated luminosity of 35.9,text {fb}^{-1} and were recorded at the LHC with the CMS detector in 2016. The analysis characterizes signal-like events by categorizing the data into various signal regions based on the number of jets, the number of mathrm {b}-tagged jets, and the missing transverse momentum. No significant excess of events is observed with respect to the expectations from standard model processes. Limits are placed on the gluino and top squark pair production cross sections using several simplified models of supersymmetric particle production with gauge-mediated supersymmetry breaking. Depending on the model and the mass of the next-to-lightest supersymmetric particle, the production of gluinos with masses as large as 2120,text {Ge}text {V} and the production of top squarks with masses as large as 1230,text {Ge}text {V} are excluded at 95% confidence level.

Highlights

  • The standard model (SM) of particle physics successfully describes many phenomena, but lacks several necessary elements to provide a complete description of nature, including a source for the relic abundance of dark matter (DM) [1,2] in the universe

  • The SM background events are generated using the MadGraph5_amc@nlo v2.2.2 or v2.3.3 generator [34–36] at leading order (LO) in perturbative quantum chromodynamics (QCD), except ttγ and tγ, which are generated at next-to-leading order (NLO)

  • The physics objects used in this calculation are produced by a jet-finding algorithm [57,58] applied to all charged-particle tracks associated to the vertex, plus the corresponding pTmiss computed from those jets

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Summary

Introduction

The standard model (SM) of particle physics successfully describes many phenomena, but lacks several necessary elements to provide a complete description of nature, including a source for the relic abundance of dark matter (DM) [1,2] in the universe. New colored states, such as gluinos (g) and top squarks (t), the superpartners of the gluon and the top quark, respectively, are expected to have masses on the order of 1 TeV to avoid fine tuning in the SM Higgs boson mass-squared term. We include additional signal regions that exploit high jet multiplicities for sensitivity to high-mass gluino models, and we rely more on observed data for the background estimations. These improvements enable us to explore targeted signal models that produce b quarks in the final state and are expected to improve sensitivity to the models explored in Refs.

Detector and simulation
Event reconstruction and selection
Background estimation
Lost-lepton and τh backgrounds
Misidentified photon background
Background from Z(νν)γ events
Background from γ +jets events
Results and interpretations
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