Search for supersymmetry in events with at least one photon, missing transverse momentum, and large transverse event activity in proton-proton collisions at 13TeV with the CMS detector in 2016

Abstract

In this thesis, a search for supersymmetry (SUSY) is presented. Events from proton-proton collisions at the CERN LHC with a center-of-mass energy of 13 TeV are considered, measured with the CMS detector. The data correspond to an integrated luminosity of 35,9 /fb, recorded in the year 2016. SUSY is an extension to the standard model of particle physics (SM), which predicts new particles, such as for example gravitinos or gluinos. In the models considered in this thesis, events with photons and gravitinos in the final state are expected. Gravitinos cannot be detected, such that non-negligible missing transverse momentum is measured in the event. If the events are produced via the strong interaction, jets are expected in addition. Events with at least one high-energy photon, large transverse jet activity, and a large missing transverse momentum are selected. The contribution of SM events is estimated using data control regions and simulated events. To increase the sensitivity of the analysis, the selection is divided into six regions. No significant excess of events above the SM prediction is observed. The analysis is interpreted among others in terms of simplified models of gluino pair production with different scenarios for the decay probabilities of thegluinos. The gluinos can decay in several steps to photons, gravitinos, and jets. Depending on the mass of the neutralino, gluino masses up to 1.5 - 2 TeV are excluded with a confidence level of 95 %. This analysis sets up to now the most stringent limits for low neutralino masses in the scenarios considered.