Higgs Sensitivity:Higgs Sensitivity:Final Combined ResultsFinal Combined Results
CDF and D0 Higgs Sensitivity Committees
18 June 2003
Recent Developments
• have new numbers for both lbb (from CDF) and bb (from D0) with bug fixes, etc.
• incorporate NN enhancement to lbb: multiply Sx0.90, Bx0.63 (C. Neu thesis)
• incorporates extended lepton and b tagging into lbb (with high eta roll-off; Winer, MMP)
• use improved mass resolution for lbb (Dorigo, Scodellaro)
• incorporate llbb into ZH channel
• combine all channels
WH channel
• extended lepton/b tagging
• 10% mass resolution
• NN factor applied: 1.6xS, 1.6xB
b tagging
•include efficiency out to ||=2, but must incorporate realistic “rolloff”
•SHW assumed flat efficiency out to ||=2
•assume no degradation due to multiple interactions
Statistical methods
Two approaches, both using mass spectrum:
• Bayesian - integrate likelihood, taking into account systematics by integrating them out
• CLs - used by LEP 2, takes into account systematics by maximizing likelihood at zero signal and SM cross section value; frequentist limit
• CLs method agrees with Bayesian for 95% CL exclusion, but find ~10% lower luminosity thresholds for discovery
ZH channel from D0
•incorporate llbb by scaling signal and background by 1.33
•uses NN for selection
•sensitivity better than SHW report
•significant acceptance from WH channel! Need to ensure that there
is no acceptance overlap with lbb channel
HSG vs SHW at 115 GeV
WH (lbb) ZH (bb)
HSG SHW HSG SHW
signal 3.8 4.6 3.6 5.5
tt 12.9 7.8 2.0 3.0
tqb/tb 7.4 5.3 1.1 5.0
Wbb/Zbb 23.1 7.7 3.1 13.8
WZ/ZZ 2.3 1.4 3.5 3.3
QCD - - 9.0 25.1
bkgd 46 22 19 50
S/B 0.56 0.98 0.83 0.78
mass window: 98-130 GeV
Pseudoexperiment results - WH
Pseudoexperiment results - ZH
WH, ZH combined (CDF + D0)
Higgs Sensitivity Versus Mass
bands are ~30% wide to account for systematics and statistical method
HSG compared with SHW
bands are ~30% wide to account for systematicsand statisticalmethod