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

2. Arguments for a “low mass” Higgs
114 < mh < in SM
LEP saw enhancement at 115 GeV.
SUSY favors mh<135GeV

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

4. 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

5. pb ->

6. 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 !!!

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

8. 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”

9. 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%

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