Multi-lepton signatures of additional scalar bosons beyond the Standard Model at the LHC

Following a prediction made in von Buddenbrock et al (2015 arXiv:1506.00612), Kumar et al (2017 J. Phys.: Conf. Ser. 802 012007), von Buddenbrock et al (2016 Eur. Phys. J. C 76 580), this paper focuses on multi-lepton signatures arising from two new hypothetical scalar bosons, H and S, at the Large Hadron Collider. These two new bosons are an extension to the Standard Model and interact with the SM Higgs boson, h. We consider two production modes for H, one being gluon fusion and the other being in association with top quarks. The decay mode is considered, where leptonic final states are studied. The CP properties of S are characterised by considering effective couplings derived from dimension six operators through SWW vertices. The nature of the S boson is considered in two separate contexts. Firstly in a simplified model, it is considered to have Higgs-like couplings. Secondly, we consider a heavy neutrino model and its interactions with the Z, W and S bosons. The predictions of the models are compared both to ATLAS and CMS results at and 13 TeV, where appropriate. The data is interpreted using a simplified model where all the signal comes from , assuming S to be Higgs-like, m _H = 270 GeV and m _S = 150 GeV. The combined result yields gives a best fit value for the parameter β _g (the strength of the Yukawa coupling of H to top quarks), . A number of regions of the phase space are suggested to the experiments for further exploration.