Low Mass Higgs @ LHC Why low mass Low Mass Higgs @ LHC Why low mass? Production characteristics Decay characteristics Overview of search strategies or who does what and how does it hang together

Arguments for a “low mass” Higgs 114 < mh < 200 @95%CL in SM LEP saw enhancement at 115 GeV. SUSY favors mh<135GeV

SM Higgs at LHC: ~10-40pb NLO Cross sections M. Spira et al. gg fusion IVB fusion

Other SM Physics Xsections (crude guestimates) Total Xsection = 1011pb b-quark pT>30GeV = 106pb W-> e/mu nu = 5x104pb Top-quark = 860pb => Always gives WW WW from QCD = 100pb Higgs = 10pb

pb ->

SM Higgs Decays WW favored over ZZ by a factor 4-50 !!! … When WW channel opens up pronounced dip in the ZZ BR … WW favored over ZZ by a factor 4-50 !!!

CMS L1 Trigger Di-electron/photon Di-muon => Only di-photon, WW, and ZZ decays matter

W,Z, and tau decays W: Z: Tau: 10% to lepton & neutrino for each e,mu,tau 70% to di-jet Z: 3.4% each ee, mu mu, tau tau 20% for di-neutrino 70% for di-jet Tau: 35% for e or mu plus 2 neutrinos 50% for other “1-prong”

Some di-boson BR’s ll = ee or mumu tt = tau tau = two isolated tracks jj = di-jet BR(WW -> lnu lnu) = 4x1% = 4% BR(ZZ -> llll) = 4x0.1 % = 0.4% BR(ZZ -> lltt) = 4x0.08% = 0.3% BR(ZZ -> llnunu) = 2x0.7% = 1.4% BR(ZZ -> lljj) = 2x2.4% = 4.8%

Higgs Search Strategies 2 leptons & missing ET Shih-Chieh’s thesis at CDF Covers 3% of total BR(H->llnunu) Di-lepton & di-jet Matthew @ CDF for mH = 150GeV sweatspot Covers 2.4% x 8% = 0.2% Traditional 4 leptons Covers 0.4% x 8% = 0.03% @ 150GeV sweatspot ll track track may double this if we’re lucky ? Kevin @ CDF in WZ mostly