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MSSM Higgs in ATLAS

ATLAS. MSSM Higgs in ATLAS. Bill Murray, November 2001. Talk Overview. Introduction to MSSM Higgs What restrictions do we know? ATLAS benchmarks Beyond the benchmark Conclusions. Basics of SUSY Higgs. 5 Higgses: h, A, H, H + and H - Mass relations:

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MSSM Higgs in ATLAS

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  1. ATLAS MSSM Higgsin ATLAS Bill Murray, November 2001

  2. Talk Overview • Introduction to MSSM Higgs • What restrictions do we know? • ATLAS benchmarks • Beyond the benchmark • Conclusions

  3. Basics of SUSY Higgs • 5 Higgses: h, A, H, H+ andH- • Mass relations: • So MA and b (or tan b) fix 5 masses (at tree level….) Tree level

  4. Masses of SUSY Higgses MH LEP limit Mh Log tanb MH+ Maximal mixing MA

  5. Couplings of SUSY Higgs Tree level a is the h,H mixing h decouples for large MA

  6. Couplings of the h to t and Z h-top coupling h-Z coupling SM like for MA>150 Drops for MA<150

  7. Coupling of the h to the b/t/m h-bottom coupling Enhanced for low MA and high tan b. i.e. when the top and Z couplings decrease Gives h radiation off b quarks. Can be used at Tevatron as well as LHC...

  8. Coupling of H to the b/t/m and t Enhanced at high tanb for mH>125GeV H-bottom coupling H-top coupling

  9. Coupling of the A to the b/t/m A-bottom coupling Enhanced for any large tanb Careful - the A width also increases….

  10. Existing Limits • LEP `benchmark’ scenarios • No mixing • Maximal mixing Least restrictive • large m • Maximal Mixing has: MSUSY=1TeV, M2=200GeV, m=-200GeV, mgluino=800GeV, Xt=2MSUSY

  11. Maximal Mixing Limit Allowing MSSM scans (e.g. h00 decays) makes less than 1GeV difference in limit

  12. Limits on mA, tanb - large m Two parameters: tanb, MA m held to 1TeV Regions of reduced Higgs to b coupling Probably LEP will exclude this scenario eventually

  13. MSSM regions surviving LEP • A heavy: Decoupling region. • The h looks like the SM Higgs, mass below 130GeV • The A/H/H+ become quasi -degenerate in Mass • Mass scale NOT KNOWN • A light, tanb large. • The h may be hard to find • … but couples to down type (b,t,m) • The A/H/H+ become light and relatively easy to see

  14. What if there was a Higgs at 115? • Essentially the whole unexcluded MSSM plane allows for a CP even Higgs at 115, depending upon loops…. • No guidance here!

  15. Tevatron Potential • Can find h if we are in decoupling (heavy A) region, luminosity arrives, and mh<120 • For High tan b, see: Significant chance of 1 Higgs

  16. Signatures in ATLAS • All SM channels relevant (hgg, tthttbb, HZZ) • If A heavy, h behaves like SM Higgs (de-coupling) • H may appear in SM channels • Decays assuming super-partners too heavy : • A, mm, tt, H hh, H+tb, cs, tn, t  H+bcsb • May also have: • c20 hc10 ,h c10c10, A/H/H+ sparticles • Zoo of possible signatures, model dependent (h OK)

  17. Higgs from Weak Boson Fusion • Motivation: • Additional potential for Higgs boson discovery • Important for the measurement of Higgs boson parameters • (couplings to bosons, fermions (taus), total width) • Detection of an invisible Higgs • proposed by D.Zeppenfeld et al. (several papers...) • s = 4 pb (20% of total cross section for mH = 120 GeV) • however: distinctive signature of • - two high PT forward jets • - little jet activity in the central region Relevant to MSSM

  18. qqH qq WW  qq l n l n • - PYTHIASignal and background simulations • - El.weak backgrounds (t-channel vector boson exchange from matrix element calculation, D.Zeppenfeld et al.) • - ISR & FSR included (PYTHIA) • Basic cuts on isolated leptons: PT > 20 GeV • |  | < 2.5 • Basic cuts on tagging jets: PT > 20 GeV •  > 4.4 • Dominant background at that level: tt production PT(tot) H tt • Additional rejection: • Mjj (inv. Mass of tag jets) • PT (tot) = PT(l1) + PT(l2) + Ptmiss + PT(j1) + PT(j2) • (less sensitive to pile-up than jet-veto over large rap.) • Jet Veto ( no jets with PT > 20 GeV in |  | < 3.2 )

  19. Main background: remaining tt background (13.1 events) WW el. weak background ( 7.1 events) mH = 130 GeV mH = 160 GeV e m decays e m decays • Much to be done: • proper estimate of forward jet tag efficiencies in a full simulation, • combination with ee and mm ignature, optimization of cuts • For the same cuts: significance is worse than in orig. publ. by Zeppenfeld et al. (ISR/FSR effects, jet calibration, efficiencies) • However: confirmed that WBF channel has a large discovery potential

  20. qqH qq t t  qq l n n l n n Combined significance (ee, mm, em): mH (GeV) 110 115 120 125 130 140 150 10 fb-1 30 fb-1 2.2 2.6 2.6 2.4 2.3 1.3 0.6 s 3.8 4.3 4.3 4.1 3.8 2.7 1.4 s - Similar basic cuts as in WW analysis - Tau mass reconstruction using collinear approximation - Optimized cuts for em, ee and mm channels mH = 115 GeV 30 fb-1 all channels (em best channel) S = 17.3 events B = 11.4 events S/B > 1 Preliminary, no systematics yet, l-had channel to be added

  21. LHC discovery potential Assuming SUSY particles are heavy Not all channels shown No holes at low L (30fb-1) • Two or more Higgs can be observed over most of the parameter • space  disentangle SM / MSSM

  22. How many Higgses? For low MA no little h visible If we see h. or H, how do we know which it is?

  23. Discovery potential for 10 fb-1 5s contours Large part of plane can be explored in 2007 Hole

  24. Hole where h is hard to see bbhbbmm region expolits enhanced coupling Is cross section calculated properly? (bb structure functions?) Does experient allow for h width Can we plug this gap?? mh

  25. A and H bosons • Large tan b: bbA and bbH enhanced • sMSSM/sSM~5000 tanb=30, mA=300GeV • H/A seen through: • tt - 300 times rate, missing neutrinos • mm - Good mass measurement • Small tanb : Would have been fun…  measurement of many couplings • (including Hhh, AZh) Recall: mA > 200 GeV: A and H are ~ degenerate

  26. A/H    h+ h : Provides best reach for large mA. Signature: two stiff opposite-sign isolated tracks (PT > 40 GeV) PTmiss or 1 b-tagged jet (bbA/H) Main challenge: reject QCD jet background. (already at trigger-level) Feasible for mA > 300 GeV: (high PT hadrons, larger PTmiss, larger rejection from isolation)  RQCD ~ 1010  QCD background << 10% (tt + Z/*  ) mA = 500 GeV tan b = 25 mA = 500 GeV tan b = 25 b-tag requirement improves S/B CMS PTmissanalysis 30 fb-1 Mass resolution ~10%

  27. Going beyond the Benchmark • bsg gives MH+>~350GeV: Benchmark simple! • Susy particles light. • Huge parameter space • Reduce by assuming (normally) mSugra • Discussed in next 2 transparencies. • nMSSM • Much more complex - I know no coherent study • General 2 HDM • Much more complex - I know no coherent study

  28. ATLAS 300 fb-1 Higgs decays via SUSY particles If SUSY exists : search for H/A  0202  01 01 5 contours ATLAS: SUGRA scan m0 = 50 - 250 GeV m1/2 = 100 - 300 GeV tan b = 1.5 - 50 A 0 = 0 No CP violation Exclusions depend on MSSM parameters (slepton masses, m)

  29. How robust is this potential ? SUSY ON ATLAS forbidden • SUSY loops can enhance/suppress Higgs production • (e.g. gg  h) and decay (e.g. h  gg) • A/H/H  sparticles can compete with SM decays Preliminary study : mSUGRAimpact of SUSY on Higgs decays to SM particles is small : -- gg  h   10% smaller -- tth/Wh   30% smaller -- ttH  tt bb not affected -- BR (A/H/H  SM particles) reduced by at most 40% Larger effects outside mSugra However : impact of mixing on couplings not studied for all possible mixing scenarios  more work needed

  30. Searching for invisible Higgs ? Signal: qq qqVV qqH Hinvisible • Cut on: • Trigger (needs h of 4.9 for jets) • Large jet-jet mass >1200GeV/c2 • Large PT miss >100GeV/c • Isolation of PT miss • Finally fjj

  31. Invisible Higgs ? Assume no systematics in background...  is fraction of SM Higgs rate For MH (or MA), below 400GeV/c2 can see a SM Higgs going 50% to invisible But IMHO systematics serious

  32. Conclusions • LHC has a large discovery potential for MSSM Higgs Bosons • Some sign of MSSM Higgs sector should be observable • Two or more Higgs bosons accessible in many cases. • MA 200-500, tanb> 15 gives all 5 • Vector Boson fusion channel significantly enhances the discovery potential • Tau tau channel in the low mass region • Enhanced WW channels • Can it be used to see invisible Higgs decays ? • New promising channels also in the MSSM section • (Charged Higgs, had. Tau decays) • To be done: • Need improved calculations (K-factors for S and B) • MC work important (Follow Tevatron data  MC  LHC) • new topics (CP violation, ...) • Understand the measurements which can be made.

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