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Detect MSSM neutral Higgs bosons at LHC

Detect MSSM neutral Higgs bosons at LHC. Simonetta Gentile Università di Roma, La Sapienza, INFN. Outline. Motivation Supersymmetric (SUSY) Higgs Experimental status Search at LHC,what can be done: few examples Conclusions. Minimal Super Symmetric Model.

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Detect MSSM neutral Higgs bosons at LHC

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  1. Detect MSSM neutral Higgs bosons at LHC Simonetta Gentile Università di Roma, La Sapienza, INFN Simonetta Gentile, Les Rencontres de Physique de la Vallée d’Aoste, 29 February.

  2. Outline • Motivation • Supersymmetric (SUSY) Higgs • Experimental status • Search at LHC,what can be done: few examples • Conclusions Simonetta Gentile, Les Rencontres de Physique de la Vallée d’Aoste, 29 February.

  3. Minimal Super Symmetric Model The MSSM is the most investigated extension of SM provides: • The unification of coupling constants • SUSY provides a ColdDarkMatter candidate • Three neutral Higgs bosons: A, CP-odd, andCP-evenH,hthe lightest. Two charged H+, and H-. • Large loop corrections depend on SUSYparameters • Unconstrained MSSM has huge number (105) of parameters • in addition SM ones, making any phenomenogical analysis • very complicated • A simplified version at some GUT scale: CMSSM/mSUGRA Most of phenomenogical analysis models are based on that. Simonetta Gentile, Les Rencontres de Physique de la Vallée d’Aoste, 29 February.

  4. MSSM parameters constrains Phenomenology decribed at Born level bytan b ,mA • Msusy,sfermion mass at EW scale • M2, SU(2)L gaugino mass at EW scale • m, supersymmetric Higgs boson mass parameter. • tan b, the ratio of the two Higgs fields doublets • A0, a universal trilinear higgs-squarks coupling at EW scale. It is assumed to be the same for up-type squarks and for down types quarks. • mA, mass of CP-odd Higgs boson. • Mgluino, it affects loop corrections for stop and bottom • couplings: gMSSM = ξ · gSM • no coupling of A to W/Z • large tanb: large BR(h,H,Att,bb) a: mixing angle between CP even Higgs bosons (calculable from tanb and MA) Simonetta Gentile, Les Rencontres de Physique de la Vallée d’Aoste, 29 February.

  5. For MA< 135 GeV (Mhmax scenario) • The ligth MSSM Higgs is SM-like MA≈ Mh Masses • For MA> 150 GeV (decoupling limit) The heavy MSSM Higgsess: MA≈ MH ≈MH± Pythia 6.226 FeynHiggs2.2 Pythia 6.226 S.G, H.Bilokon,V.Chiarella,G.Nicoletti ATL-PHYS-PUB-2007-001 Sven Heinemeyer Atlas meeting 29.01.2008 Simonetta Gentile, Les Rencontres de Physique de la Vallée d’Aoste, 29 February.

  6. MSSM Higgs Production V*=W/Z • Main production mechanism ~SM • For high and moderate tanb theproduction with b quarks is enhanced • For mA >>mZ A/H behave very similar →decoupling region • A, H, H± cross section ~tanb2 Simonetta Gentile, Les Rencontres de Physique de la Vallée d’Aoste, 29 February.

  7. Production cross section • At small tanb gg→h,H,A dominant • Vector boson fusion process • pp→qq→qq+WW/ZZ→qq+h/H • important at m h~ m hmax • Higgsstrahlung neglegible • At high tanb associatedb quarks production dominates • pp → bb →h/H/A+ bb =h,H,A Abdelhak Djouadi arXiv:hep-ph/0503173v2 (2005) Simonetta Gentile, Les Rencontres de Physique de la Vallée d’Aoste, 29 February.

  8. Branching ratio • Decoupling region • MA≥ 150 GeV tanb ≈30 • or MA≥ 400-500 GeV tanb=3 Production rate • Decay bb dominates, • tt lower background • weaker sensitivy on • SUSY parameters Abdelhak Djouadi arXiv:hep-ph/0503173v2 (2005) Simonetta Gentile, Les Rencontres de Physique de la Vallée d’Aoste, 29 February.

  9. Branching ratio • Intense coupling region tanb ≈30 MA~ 120-140 GeV • Coupling to W,Z up quarks suppressed • Coupling down quark (b) and t enhanced • Decay bb,tt dominates • Decay mm possible Abdelhak Djouadi arXiv:hep-ph/0503173v2 (2005) Simonetta Gentile, Les Rencontres de Physique de la Vallée d’Aoste, 29 February.

  10. Benchmark scenarios • mhmax scenario It allows the maximum value for mh(Xt =2MSUSY). It can be obtained conservative tanb exclusion bounds • no-mixing scenario No mixing in scalar top sector (Xt =0) • small aeff scenario Hb coupling~ sinaeff/ cos b can be zero: aeff→0: Main decay mode vanishes, important search channel vanishes • gluophobic Higgs scenario hgg coupling is small: main LHC production mode vanishes. Simonetta Gentile, Les Rencontres de Physique de la Vallée d’Aoste, 29 February.

  11. MSSM Constrained: • Two Higgs doublets →h0, H, A, H+, H- • Three neutral Higgs bosons: H,A, CP-odd, andh the lightest CP-even. • Large loop corrections depend on SUSYparameters (expecially stop): Msusy, M2, m, tan b, A,mA,mgluino • Xt~ A= 61/2 Msusy, |m|<< Msusy for maximal top mixing • Xt=0 no mixing scenario • Measurement of Higgs masses, coupling and Br  test of theory • Varying mAtanβ,keeping all other SUSY parameters fixed. Simonetta Gentile, Les Rencontres de Physique de la Vallée d’Aoste, 29 February.

  12. Low tanb is not completely excluded: search for LHC with pp->A; A->Zh, gg, tt LEP legacy Mt [GeV]= 169.3 174.3 179.3 183.0 Excluded: (mhmaxscenario) mh>92.8 GeV mA>93.4 GeV tanb 0.7 2.0 Excluded MH±>78.6 GeV High tanb area for search at LHC with pp->bb h/ H/A h/H/A->mm, tt decays Simonetta Gentile, Les Rencontres de Physique de la Vallée d’Aoste, 29 February. Eur.Phys. J C 47, 547

  13. Tevatron results Exclusion Limits @ 95% CL CDF & D0 have not observed a Higgs signal yet Interpretation of the limits Simonetta Gentile, Les Rencontres de Physique de la Vallée d’Aoste, 29 February. Anton Anastassov Aspen 2008

  14. Quest & strategy Look for MSSM bosons in the entire parameter space. • Using the same analysis strategy for SM ,MSSM • Among all channels studied from ATLAS and CMS focus on: • pp→bb h/ H/ A– moderate and high tanb • h/ H/ A ->mm • h/ H/ A ->tt • pp→A at low tanb • A→Zh • Z→  (=e, m) • h→bb • pp→A/H→ c02,3,4 c02,3,4 Simonetta Gentile, Les Rencontres de Physique de la Vallée d’Aoste, 29 February.

  15. Light higgs boson L =30fb-1 h • VBF dominates at low luminosity • Large space covered by several • channel • Region around mh~ 95GeV • difficult • h→mm channel at low masses h/A/H CMS TDR L =300fb-1 NOT UPDATED Simonetta Gentile, Les Rencontres de Physique de la Vallée d’Aoste, 29 February. ATLAS

  16. bb h/A→bbmm • Associated h/A/H production with b-jets → large s • The adavange of tt channel due to the mass is counterbalanced by difficulty of identify t decays • (smaller detector acceptance, n in final state) • Excellent m resolution of detectors Production rate h→mm and h →tt signal background S.G., H.Bilokon, V.Chiarella,G.Nicoletti, Eur.Phys. J. C. 52, 229-245 (2007) Simonetta Gentile, Les Rencontres de Physique de la Vallée d’Aoste, 29 February.

  17. Atlas bb→h/Amm MA=110.31 GeV, Mh= 110 GeV, tanb=45 Atlas : tanb 15-50 mA 95-130 GeV • 2 m pT>20GeV • 2 jets pT>10GeV • 1 b-jet (pT>15GeV) • Mmm • m-isolation,no hadronic • activity • Background bbZ→bbmm • tt →bbmm • ZZ→bbmm Full detector simulation Corresponding to L=300fb-1 Simonetta Gentile, Les Rencontres de Physique de la Vallée d’Aoste, 29 February.

  18. Atlas Background evaluation • bbZ→bbmmlarge cross section (s≈ 22.8 pb) large theoretical uncertainties (≈ 25%) Proposed data driven method based on bbZ→bbee • Rate of signal suppresed by Background same rate: same production diagram, and lepton universality different inner bremsstrahlung and detector reconstruction Ratio stable & without large corrections factor Simonetta Gentile, Les Rencontres de Physique de la Vallée d’Aoste, 29 February.

  19. Atlas h/A/H significance reach L=300 fb-1 L=10 fb-1 L=30 fb-1 Mhmax scenario Simonetta Gentile, Les Rencontres de Physique de la Vallée d’Aoste, 29 February.

  20. Atlas Discovery contours 5 s at L =30 fb-1 ---- no systematic H+A h+A h+H+A ATLAS CMS TDR Simonetta Gentile, Les Rencontres de Physique de la Vallée d’Aoste, 29 February.

  21. Others channel:t decays • Full leptonic: bbH→bbtt→em+ETmiss • Lower rate than full hadronic or hadronic/lepton Br(t→lnn) ~0.17 • Clean signal and easy trigger • Higgs mass reconstruction using collinear approxomation • Approssimation method requires excellent missing ETresolution • Main background:Z+jet,ttbar,Zbb Simonetta Gentile, Les Rencontres de Physique de la Vallée d’Aoste, 29 February.

  22. Higgs Search in A→ Zh channel • Low tanb region • Final state Z→ ll (l = e,m) h →bb • Low tanb Mz+mh≤ MA≤2mtop (highest Br) • Depends strongly on MSSM parameters • Main backgrounds: Zbb,ttbar and Z+jet • Systematic can be important At Large value of M2 and m can dominate A→cc L=30fb-1 Z+jet tt 5s contour Zbb signal Simonetta Gentile, Les Rencontres de Physique de la Vallée d’Aoste, 29 February.

  23. Summary of CMS reach in MA-tanb Associated production Inclusiveproduction Simonetta Gentile, Les Rencontres de Physique de la Vallée d’Aoste, 29 February.

  24. ATLAS reach for MSSM Higgs bosons Atlas L=300fb-1 Not updated • whole plane covered in CP conserving benchmark scenarios • significant area where only h is observable • At least one Higgs boson observable • significant area where only h is observable • Difficult to distinguish from SM Simonetta Gentile, Les Rencontres de Physique de la Vallée d’Aoste, 29 February.

  25. LHCsearches for MSSM higgses Other discovery channels possible .. : • h→ gg inclusive production and production in association tth final states • h,A,H → mm inclusive and bb associated • H →bb in association with bb • h,A,H →tt with 2 ,  +t-jet and 2 t-jet final states. • ..... • gb → t H±, H± →tn • gg →tt → H± bWb • Note: • They only include SM-particles to Higgs interactions • This assumes no interaction between Higgs & sparticle sectors: • i.e., SUSY mass scales are heavy Simonetta Gentile, Les Rencontres de Physique de la Vallée d’Aoste, 29 February.

  26. SUSY & Higgs interplay If SUSY kinematically accessible, then real production of sparticles. • Higgs can decay directly to or come from decay of SUSY particles • Associated production modes: e.g, squark-squark-Higgs • SUSY particles suppress or enhance loop induced production or decays Higgs into sparticle decay modes can compete with SM modes: H/A →c02c02→ 4 ± X H± →c02c±1→ 3 ± X Pioneering papers: [1] F. Moortgat, S. Abdullin, D. Denegri”. hep-ph/0112046 [2] M.Bisset, F. Moortgat and S. Moretti “Eur.Phys.J.C30:419-434,2003. [3] C. Hansen, N. Gollub, K. Assamagan, T. EkelofEur.Phys.J.C44S2:1-9,2005. Simonetta Gentile, Les Rencontres de Physique de la Vallée d’Aoste, 29 February.

  27. A/H susy decays Access to low tanb with A/H->c20c20->4  + ETmiss CMS Chosen points in mSUGRA • Background • SUSY, SM: tt, ZZ, Zbb • Selections: • Lepton isolation • Jet veto • ETmiss, pT4l < 80 GeV • Z veto Point C after selections Simonetta Gentile, Les Rencontres de Physique de la Vallée d’Aoste, 29 February.

  28. A/H susy decays Access to low tanb with A/H->c20c20->4  CMS tanb = 5 150<m½ <250 30<m0 <120 tanb = 10 150<m½ <250 m0 <120 Simonetta Gentile, Les Rencontres de Physique de la Vallée d’Aoste, 29 February.

  29. A/H susy decays A,H →c02,3,4 c02,3,4→4 ±+ EmissT A,H →c+2 c-1,2 →4 ±+ EmissT =eμ s(pp →H/A) Br(A,H →4 ±+ N) tanb = 20 MA=500GeV M2[GeV] c20c20 c3,40c3,40 m [GEV] M.Bisset,N.Kersting,F.Moortgat,S.Moretti,arXi:0709.10029[hep –ph] Simonetta Gentile, Les Rencontres de Physique de la Vallée d’Aoste, 29 February.

  30. Search in a LHC detector Point A M0=125 GeV tanb=20 Point B M0=400 GeV tanb=20 M½=165GeV sign(m)=+1 A0=0 • Representive points studied: • MSSM representative Points • MSugra representative Points • Discovery potential in a typical LCH detector investigatedwith this selections: • 4 leptons |h |< 2.4 ,ET > 7.4 GeV • lepton Isolation • 2pairs of opposite sign • |MZ ±10 GeV| veto • 20 GeV<ET < 80 GeV • ETjet < 50 GeV Simonetta Gentile, Les Rencontres de Physique de la Vallée d’Aoste, 29 February.

  31. Reach for MSSM Higgs bosons in c02,3,4c02,3,4or c1,2+c2- pairs Point 2 MA=600 GeV tanb=35 M1=100GeV M2=200 GeV m=-200GeV Ml=150GeVMt= 250Gev mg=800GeV Mq=1000GeV Point 1 MA=500 GeV tanb=20 M1=90GeV M2=180 GeV m=-500GeV Ml=Mt= 250GeV mg=Mq=1000GeV Simonetta Gentile, Les Rencontres de Physique de la Vallée d’Aoste, 29 February.

  32. Discovery region for H/A →c02,3,4c02,3,4c1,2+c2- Set 1 superimposed to Atlas discovery reach with SM particles 1.H → ZZ* →4  2.tH →bH+,H+ →tn +cc 3.tth ,h →bb 4.h →gg 5.bbH/A, H/A →bb 6.H+ →tb +c.c. 7.H/A →m+m- 8.H/A →t+t- 9.gb →tH+, H+ →t+n 10.H →hh →bbgg 11. A →Zh →-bb 12.H/A →tt SM decays limit derived with hypotesis that H/A can’t decay in SUSY particles.DIFFERENT parameter!! Simonetta Gentile, Les Rencontres de Physique de la Vallée d’Aoste, 29 February.

  33. Discovery region for H/A →c02,3,4c02,3,4c1,2+c2- Set 2 superimposed to Atlas discovery reach with SM particles 1.H → ZZ* →4 2.tH →bH+,H+ →tn +cc 3.tth ,h →bb 4.h →gg 5.bbH/A, H/A →bb 6.H+ →tb +c.c. 7.H/A →m+m- 8.H/A →t+t- 9.gb →tH+, H+ →t+n 10.H →hh →bbgg 11. A →Zh →bb 12.H/A →tt SM decays limit derived with hypotesis that H/A can’t decay in SUSY particles.DIFFERENT parameter!! Simonetta Gentile, Les Rencontres de Physique de la Vallée d’Aoste, 29 February.

  34. Conclusions • Atlas & CMS are preparing for first collision data • Discovery potential of MSSM Higgs boson has been estimated by ATLAS and CMS. • A early discovery of a neutral MSSM boson in some channels (e.g.bb h/A→mm ) looks possible with integrated luminosity =10 fb-1 , i.e. after only one year of data taking. • First data has the possibilty to exclude/or confirm the entire MSSM • Others decay channel (as c20 c20) can be explored later for unexplored region of parameter plane. Simonetta Gentile, Les Rencontres de Physique de la Vallée d’Aoste, 29 February.

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