A heavy scalar of mass 270 GeV and its possible connection to the 750 GeV excess

Abstract

Run 1 of the LHC saw many interesting and surprising results, hinting at physics beyond the Standard Model. One of these is the search for lepton pairs in association with high missing energy, which produced a sizeable excess in its rate from both the ATLAS and CMS collaborations. While ATLAS and CMS interpret this using a supersymmetric model, we have shown that the excess can partly be explained by the existence of a new heavy scalar boson, H. This heavy scalar can decay to weak vector bosons and also Standard Model Higgs bosons and missing energy, making it a prime candidate in the search for high pT di-lepton pairs. An analysis is performed to determine the rate of di-lepton production with large missing energy for opposite sign pairs. We show that the heavy scalar produces a non-negligible rate, but cannot fully explain the excesses. For this reason, we look also to incorporating a full two Higgs doublet model to enhance this rate, where the pseudo-scalar A in the spectrum of new particles is considered to be a candidate for the Run 2 di-photon excess at 750 GeV.