Search strategies for pair production of heavy Higgs bosons decaying invisibly at the LHC

摘要

The search for heavy Higgs bosons at the LHC represents an intenseexperimental program, carried out by the ATLAS and CMS collaborations, whichincludes the hunt for invisible Higgs decays and dark matter candidates. Nosignificant deviations from the SM backgrounds have been observed in any ofthese searches, imposing significant constraints on the parameter space ofdifferent new physics models with an extended Higgs sector. Here we discuss analternative search strategy for heavy Higgs bosons decaying invisibly at theLHC, focusing on the pair production of a heavy scalar $H$ together with apseudoscalar $A$, through the production mode $q \bar q \to Z^\ast \to HA$. Weidentify as the most promising signal the final state made up of $4b +E_T^\text{miss}$, coming from the heavy scalar decay mode $H \to hh \to b \barb b \bar b$, with $h$ being the discovered SM-like Higgs boson with $m_h=125$GeV, together with the invisible channel of the pseudoscalar. We work withinthe context of simplified MSSM scenarios that contain quite heavy sfermions ofmost types with ${\cal O}(10)$ TeV masses, while the stops are heavy enough toreproduce the 125 GeV mass for the lightest SM-like Higgs boson. By contrast,the gauginos/higgsinos and the heavy MSSM Higgs bosons have masses near the EWscale. Our search strategies, for a LHC center-of-mass energy of $\sqrt{s} =$14 TeV, allow us to obtain statistical significances of the signal over the SMbackgrounds with values up to $\sim$ 1.6$\sigma$ and $\sim$ 3$\sigma$, fortotal integrated luminosities of 300 fb$^{-1}$ and 1000 fb$^{-1}$,respectively.