PPD/Southampton seminarB W Kennedy, RAL PPD23 Nov 2001 Survey of Higgs searches at CMS B W Kennedy, RAL/PPD 23 November 2001

PPD/Southampton seminarB W Kennedy, RAL PPD23 Nov 2001 Contents Short tour of the CMS detector Standard model Higgs search strategy MSSM Higgs search strategy Summary and conclusions

PPD/Southampton seminarB W Kennedy, RAL PPD23 Nov 2001 UK groups in CMS Bristol Brunel ICSTM RAL

PPD/Southampton seminarB W Kennedy, RAL PPD23 Nov 2001 Overview of CMS

PPD/Southampton seminarB W Kennedy, RAL PPD23 Nov 2001 Experimental challenges Enormous data rate Fast detectors Fast triggering Almost all data rejected by trigger Underlying events Radiation environment Small signals, large backgrounds

PPD/Southampton seminarB W Kennedy, RAL PPD23 Nov 2001 SM Higgs Searches Search strategy depends on m H Need high enough BR and low enough background Current limits on m H Upper limit very model-dependent almost certainly < 1TeV Lower limit From LEP, m H > GeV, 95% cl LEP Combined likelihood ratio

PPD/Southampton seminarB W Kennedy, RAL PPD23 Nov 2001 SM Higgs branching ratios MZMZ Higgs mass (GeV) Branching ratio H H ZZ

PPD/Southampton seminarB W Kennedy, RAL PPD23 Nov 2001 SM Higgs width SM Higgs width Higgs is narrow for m H < 2m Z, but very wide at higher masses

PPD/Southampton seminarB W Kennedy, RAL PPD23 Nov 2001 Summary of SM searches 1 years data taken at high LHC luminosity H WW l l

PPD/Southampton seminarB W Kennedy, RAL PPD23 Nov 2001 H (100 GeV) Cleanest channel for light H (mH < 140GeV), but needs excellent ECAL resolution

PPD/Southampton seminarB W Kennedy, RAL PPD23 Nov 2001 H ZZ* 4 (130GeV) Clean channel - good for light H, and gold-plated for m H > 2m Z. H ZZ* 4e is equally good. For m H > 800GeV, increasing H and decreasing statistics kill this channel

PPD/Southampton seminarB W Kennedy, RAL PPD23 Nov 2001 Heavy H 4 l signal Signal expected in 1 year of high-luminosity running, for m H = 600 and 800 GeV. Note considerable increase in H from 600GeV to 800GeV

PPD/Southampton seminarB W Kennedy, RAL PPD23 Nov 2001 H b-bbar (100GeV) High statistics, but large background.

PPD/Southampton seminarB W Kennedy, RAL PPD23 Nov 2001 SM Higgs discovery plot Combination of decay channels will provide at least 5 significance over whole mass range for SM Higgs pb -1 corresponds to 1 year of high- luminosity LHC running.

PPD/Southampton seminarB W Kennedy, RAL PPD23 Nov 2001 Supersymmetric Higgs h 0 looks like light SM H 0 (as long as M A > 400GeV) SM H search strategy applies Use h 0 for clean signal H 0, A 0, H are complicated Signatures depend on masses and tan Two experimental approaches Decays to SM particles - similar to SM analysis Decays to sparticles

PPD/Southampton seminarB W Kennedy, RAL PPD23 Nov 2001 MSSM discovery contours Incomplete coverage of m A - tan plane - note hole at low tan for 80< m A <250GeV. (May partly be filled by searching for sparticle decay modes.) CMS/ATLAS are unlikely to provide the final word on the SUSY Higgs sector.

PPD/Southampton seminarB W Kennedy, RAL PPD23 Nov 2001 Summary and conclusions Standard-model H 0 (or SM-like h 0 ) will be discovered at LHC over the whole allowed mass range Some or all MSSM Higgses may be discovered, but some regions of MSSM parameter space cannot be covered

PPD/Southampton seminarB W Kennedy, RAL PPD23 Nov 2001

PPD/Southampton seminarB W Kennedy, RAL PPD23 Nov 2001 CMS Date rate Raw data rate bytes/sec - about 10 6 CD-ROMs/sec Event builder rate bit/sec Equivalent to all global Telecom networks

PPD/Southampton seminarB W Kennedy, RAL PPD23 Nov 2001 Underlying events

PPD/Southampton seminarB W Kennedy, RAL PPD23 Nov 2001 Radiation environment

PPD/Southampton seminarB W Kennedy, RAL PPD23 Nov 2001 Trigger and DAQ statistics 40 MHz beam-crossing rate ~ 1GHz interaction rate Level-1 trigger 100 kHz rate 0.25% % rejected Level-2 trigger 10 kHz rate 0.025% % rejected Level-3 trigger 100 Hz rate stored % % rejected In hardware In software

PPD/Southampton seminarB W Kennedy, RAL PPD23 Nov 2001 Trigger acceptance

PPD/Southampton seminarB W Kennedy, RAL PPD23 Nov 2001 ECAL energy resolution

PPD/Southampton seminarB W Kennedy, RAL PPD23 Nov 2001 MSSM contours enlarged m t =175GeV m SUSY = 1TeV

PPD/Southampton seminarB W Kennedy, RAL PPD23 Nov 2001 Sparticle decay contours enlarged A0,H leptons Relies on 0 being light enough Also depends on slepton mass