Search for new physics in events with two soft oppositely charged leptons and missing transverse momentum in proton–proton collisions at √s=13TeV

Abstract

A search is presented for new physics in events with two low-momentum, oppositely charged leptons (electrons or muons) and missing transverse momentum in proton-proton collisions at a centre-of-mass energy of 13TeV. The data collected using the CMS detector at the LHC correspond to an integrated luminosity of 35.9fb−1. The observed event yields are consistent with the expectations from the standard model. The results are interpreted in terms of pair production of charginos and neutralinos ( χ±1and χ02) with nearly degenerate masses, as expected in natural supersymmetry models with light higgsinos, as well as in terms of the pair production of top squarks ( t), when the lightest neutralino and the top squark have similar masses. At 95% confidence level, wino-like χ±1/ χ02masses are excluded up to 230GeVfor a mass difference of 20GeVrelative to the lightest neutralino. In the higgsino-like model, masses are excluded up to 168GeVfor the same mass difference. For tpair production, top squark masses up to 450GeVare excluded for a mass difference of 40GeVrelative to the lightest neutralino.