1. 1 High energy photon pairs: L1/HLT Studies Vladimir Litvin, Toyoko Orimoto Caltech, CMS Group Meeting 13June 2007

2. 2 HLT Egamma Decrease in EG HLT efficiencies with increasing mass resonance due to tight cut on energy deposition in HCAL for EG objects… If E > 6 GeV in HCAL for cluster from ECAL Barrel (8 GeV for ECAL Endcap), then the HLT object is considered *not* an EG object.. Currently this cut is too tight for very high energy diphotons Utilize an H/E cut instead… Two additional bits were added in 1_3_1_hlt5 for high energy EM stream, based on a 5% H/E cut

3. 3 H/E Selection Check signal and born/box background efficiencies with different H/E cuts (CMSSW_1_3_1_hlt4) HLT photon bits with H/E cut: HLT1Photon HLT2Photon

4. 4 Next Steps Ongoing: Looking at comparison between hlt2-hlt3-hlt4-(hlt5) Production: CMSSW_1_3_1_hlt5 Produce gamma+jet and QCD backgrounds with generator preselection (working on filter now) Working on gamma+jets and 2gamma+jets Alpgen samples with Delhi Univ (S. Bhattacharia) Analysis: Energy correction Try to reproduce results from PTDR CSA07: Diphoton skim for CSA07 implemented, as part of QCDAnalysis package