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The Standard Model (SM) with a single Higgs boson is the simplest scenario to give masses to the weak bosons to explain the electroweak symmetry breaking, yet nature has always given us more puzzles to ruin our naive wishes. 3 fermion families, the beautifully minimal SU(5) GUT turned out to be not what nature had in mind, to name a few. The Higgs sector may well also hold more rich secrets than the minimal SM would suggest, and additional Higgs doublets are well known extensions of the SM which are just as likely. In the popular extension of the Higgs sector with Two Higgs Doublet Models that includes Minimal Super-Symmetric Model (MSSM) as a special case, the extended Higgs sector is necessarily extended to with two doublets with includes the lightest neutral Higgs h0 behaving very similar to the SM Higgs, while there are additional heavy neutral Higgs H0,A0 and charged H+-. The ratio of u/d vacuum polarization values is denoted as tan(beta) in the MSSM and the experimental constraints favor a largish . Among the remaining parameter space not ruled out by existing searches, a large fraction is in the regime with moderate or large tan(beta) . This results in with preferred large couplings of A0/H0 to b quark in particular while couplings to top quark and W/Z are suppressed. An interesting consequence is that the production of H/A in association with b quarks being significantly enhanced by a factor proportional to tan2(beta) to allow possible early observations. Further more, the decays of H/A are dominated by bb(bar) mode followed by tau pairs and all other modes much smaller. This also puts a premium on the search for the H/A -> bb(bar) decay mode. The early studies of the MSSM Higgs production concentrated on the bbH/A production:
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Our analysis is therefore a search for H/A decays to bb(bar) and an additional associated b quark from production. The analysis challenge starts with the trigger as the cross section of just 3 jets with rather moderate Pt has a substantial QCD background. b-tags at trigger and analysis level become a crucial element. This analysis is aimed for the release of results for June 2015 is association with the The initial analysis with the ATLAS 8 TeV data from Run 1 led to the Stanford Ph.D thesis of Katie Malone in 2015, while the ongoing much improved analysis with 13 TeV data from Run 2 is targeting for result release for 2017 winter conferences.
Working Information
Run 1 Analysis team: Katie Malone, Giacinto Piaquadio, Tim Barklow and Su Dong (former analyst: Emanuel Strauss)
Run 2 Analysis team: Tim Barklow, Su Dong + collaborating groups from Poland and Serbia.
bH analysis working Twiki (ATLAS internal)
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