Search for the pair production of light top squarks in the $\mathrm{e}\mu$ final state in proton-proton collisions at $\sqrt{s} = 13~\mathrm{TeV}$

A search for the production of a pair of top squarks in proton-proton collisions at the CERN LHC is presented. This search targets a region of the parameter space where the kinematics of top squark pair production and top quark pair production are very similar, due to the mass of the neutralino being small. The search is performed with $36.9~\mathrm{fb}^{-1}$ of proton-proton collisions collected by the CMS detector, using events containing one opposite-sign electron-muon pair. The search is based on a precise estimation of the $\mathrm{t}\bar{\mathrm{t}}$ background, and the use of the $M_{\textrm{T2}}$ variable that combines the transverse mass of each lepton and the missing transverse energy. No excess of events is found over the standard model predictions and exclusion limits are placed at $95\%$ confidence level on the production of top squarks up to masses of 200 GeV for models with $m_{\widetilde{\mathrm{t}_1}}$ $-$ $m_{\widetilde{\chi}^{0}_{1}}$ $\simeq$ $m_{\mathrm{top}}$.