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

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Presentation on theme: "PPD/Southampton seminarB W Kennedy, RAL PPD23 Nov 2001 Survey of Higgs searches at CMS B W Kennedy, RAL/PPD 23 November 2001."— Presentation transcript:

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

2 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

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

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

5 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

6 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

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

8 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

9 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

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

11 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

12 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

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

14 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.

15 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

16 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.

17 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

18 PPD/Southampton seminarB W Kennedy, RAL PPD23 Nov 2001

19 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

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

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

22 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

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

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

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

26 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


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