1 / 30

MSSM Higgs Searches at LEP

Tord Ekelöf Uppsala University Sweden. MSSM Higgs Searches at LEP. What is the rational for supersymmetry? SM has problems with quadratic divergencies (mass hiarchy problem) Supersymmetry l eads to coupling unification at high energy Supersymmetry needed for superstrings->supergravity->

topper
Download Presentation

MSSM Higgs Searches at LEP

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Tord Ekelöf Uppsala University Sweden MSSM Higgs Searches at LEP Fourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001

  2. What is the rational for supersymmetry? SM has problems with quadratic divergencies (mass hiarchy problem) Supersymmetry leads to coupling unification at high energy Supersymmetry needed for superstrings->supergravity-> unification of general relativity and quatum field theory Fourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001

  3. e+, e+ Z,W H0 Z,W e- e-, Introduction • SM One Higgs Field Doublet • One physical Higgs H • Production • Higgsstrahlung • Vector boson fusion, small • Decay H->bb, , W*W*... • MSSM Two Higgs Field Doublets • Five physical Higgs h0 A0 H0 H+ H- e+ Z0 Z0 e- H0 Fourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001

  4. MSSM free parameters • MSUSY Sfermion mass parameter at EW scale •  SUSY Higgs mass parameter • M2 SU(2) gaugino mass param at EW scale • Xt Stop mixing term=At- tan, At trilinHt • tan ratio between vacuum expectation values of Higgs field doublets • mA A Higgs boson mass • mg Gluino mass • On tree level mh calculable from (mA,tan) and mh< mz. In one and two loop corrections to production cross-sections and branching ratios all free parameters are involved. Can make mh larger. ~ ~ ~ Fourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001

  5. A0 A0 Z0 Z0 Z0 Z0 h0 h0 h0 h0 e- e- e+ Z0 Z0 e+, e+ e- h0 Z,W • MSSM Higgs production • h0 • Higgsstrahlung, SMsin2(-) • Vector boson fusion, small • Higgs pair production, SMcos2(-) • A0 • Higgs pair production, SMcos2(-) • h0 decay if 2mA<mh • H0 • Higgsstrahlung if  large, SMcos2(-) • H+H- • Pairproduction h0 Z,W e- e+ e-, e+ A0 h0 A0 e+ Z0 Z0 e- H0 e+ H+ Z0 e- H- Fourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001

  6. -   • MSSM Higgs decay • h • “standard” h0->bb, +- • invisible, LSP/Majoron h0->1010, JJ • fermiophobic, 2HDM type I h0-> • flavour independent, MSSM large  h0->cc, ss, gg • A • “standard” A0->bb, +- • bosonic A0->Z0h0 • H+- • “standard”, 2HDM if at LEP2 H+-->cs,  • bosonic, 2HDM type I H+-->W*A0 - - - Fourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001

  7. MSSM Bench Mark Scenarios • Three points in the MSSM parameter space • plus general parameter space scan Parameter1. mhmax2. no mixing3. large general MSSM scan unit GeV MSUSY 1000 1000 400 200 to 1000  -200 -200 1000 -500 to +500 M2 200 200 400 200 to 1000 Xt =At- tan  2MSUSY 0 -300 -2MSUSY to 2MSUSY mg 0.8MSUSY 0.8MSUSY 200 mA 4-1000 4-1000 4-1000 4 to 1000 tan 0.4-50 0.4-50 0.4-50 0.4 to 50 Fourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001

  8. 1. Mhmax scenario • Designed to maximize the largest h0 mass value as function of tan with the aim to obtain the most conservative exclusion of tan, or , conversely, to possibly exclude MSSM by excluding h0 up to a maximal limit mhmax< 130 GeV, which depends on the exact value of mtop=174.3+-5.1 GeV. • 2. No-mixing scenario • Same as mhmax but with no mixing in the stop sector to see the effect of mixing, mhmax<114 GeV • 3. Large- scenario • In this scenario h0 (or H0) does not decay to b quarks in certain parameter-space regions. Motivates flavor independent search. mhmax<108 GeV Fourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001

  9. Searches for h and A with data collected up to 209 GeV • e+e-->Zh same as SM with production cross section reduced by sin2(-) and different decay BRs • e+e-->hA has cross section proportional to cos2(-) with final states bbbb (dominates), +-bb and bb+-. Cross-section largest when mAmh. - - - - Fourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001

  10. LEP combined distribution of CLb in the mhmaxscenario Along the mAmh diagonal Distribution of confidence (tan>20, cos2(-) 1) level in the (mA,mh) plane Fourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001

  11. LEP combined CLs in the mhmaxscenario Along the mAmh diagonal Distribution of exclusion (tan>20, cos2(-) 1) in the (mA,mh) plane mA>91.9(95.0) GeV mh>91.0(94.6) GeV observed expected observed expected Fourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001

  12. LEP combined exclusion plots in the mhmax scenario in tan vs mh, mA and mH+ planes excluded region 0.4(0.5)<tan <2.4(2.6) Fourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001

  13. Exclusion plots in the mhmaxscenario in tan vs mh planes for A, D and O ALEPH DELPHI OPAL mh> 89.6(91.7) 89.8(89.0) 79.3(85.1) tan> 0.7 0.49(0.54) 0.80(1.1) tan< 2.2 2.36(2.36) 1.7(1.9) OPAL Fourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001

  14. LEP combined exclusion for the no mixing scenario in the mA vs mh and the tan vs mh andmA planes mh>91.5(95.0) mA>92.2(95.3) excluded 0.7(0.8)<tan <10.5(16.0) Fourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001

  15. Exclusion plots in the no mixing scenario in tan vs mh planes for A, D and O ALEPH DELPHI OPAL mh> 89.8(89.0) 80.9(85.6) tan> 0.5 0.59(0.72) 1.2(1.2) tan< 6.0 9.36(9.36) 3.8(4.6) OPAL Fourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001

  16. Production and decay of charged Higgs bosons 2HDMs predict s-channel pair-production of H+H- with a tree-level cross-section which is fully determined by (mH+,s) and with H+H- decay into cscs, cs- and +-. No prediction for the BR(H+->+). In tree-level MSSM mH+>mW and mH+>mA. Search for qqqq, qqp and p final states. Use equal masses constraint, acoplanarity, H+ zero spin,  polarization (A,D) and cs identification (D). - - - - - - / / Fourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001

  17. Searches for charged Higgs, exclusion plots from of A, D, L & O ALEPH DELPHI L3 OPAL mH+<78.0(76.9) 73.8(75.4) 65.6(75.1) 72.2(74.5) Fourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001

  18. 1-CLb for charged Higgs, ADO and ALDO and for different BR(H->) Fourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001

  19. Combined ALDO searches for charged Higgs, mass limit and cross-section limit mH+>78.6(78.8) Combimed searches for charged Higgs BR(H->) vs H+ mass, and cross-section limit Fourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001

  20. The L3 charged Higgs excess at 68 Gev Fourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001

  21. Comparison with charged Higgs hadronic decay mass distributions in A, D and O    Fourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001

  22. Neutral Higgs flavour-independent hadronic decays In both the SM and in the MSSM the neutral Higgs decay predominantly into bb or +-. In MSSM large- scenario and certain other 2HDMs Higgs decays into cc or gg can become predominant. Same as SM analysis of e+e-->Z0H0, with H0->qq but without imposing requirement on the qq flavour. SM production cross-section and BR(H->had)=1 assumed. - - - - - Fourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001

  23. Flavour-independent search for a neutral Higgs ALEPH ALEPH mHinv>109.4(109.8) OPAL mHinv>101.8(107.3) Fourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001

  24. Higgs decay into photon pairs - fermiophobic Higgs In the MSSM h0 can decay into two photons via a quark or W-boson loop, but rates are low ~10-3. In other models, like 2HDM Type I, h0 only couples to gauge bosons (i.e not to fermions) for certain choices of parameter values. Analysis made assuming SM Higgs production cross-section and BR(Higgs->qq or l+l-) set to 0. - Fourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001

  25. Search for Higgs decaying into photon pairs ALEPH mH>105.4 OPAL mH>105.5 (106.4) L3 () mH>104.3 (104.4) L3 (,WW) mH> 104.8 (108.4) Fourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001

  26. LEP combined data for h° -> 2 Fourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001

  27. Higgs decay to invisible particles e+e+->Z0h0 where Z0 ->qq or l+l- at SM cross-section h0->1010 , lightest neutralinos (R parity cons., LSPs) or h0->JJ , Majorons or h0->other invisible (undetectable) particles, BR=100%. Mmiss=recoil mass, Mvis=visible mass M2miss=s-2mZEviss/Mvis+mZ2 - Fourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001

  28. Searches for invisibly decaying Higgs For BR(H->inv.)=100% ALEPH minv>114.1(112.6) DELPHI minv>113.0(110.7) OPAL minv>107.0(107.4) For BR(H->inv.)=any DELPHI minv=112.7 Fourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001

  29. LEP combined data for h°->invisible Fourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001

  30. Conclusion NO MSSM/2HDM HIGGS FOUND Combined results of the four LEP experiemnts MSSM mhmax mh>91.0 (94.6) GeV All limits at 95%CL mA>91.9 (95.0) GeV 0.5<tan<2.4 (0.5<tan<2.6) excluded Charged Higgsm>78.6 (78.8) GeV Flavour blind Higgs m>112.9 (113.0) GeV Photonic Higgs m>108.2 (109.0) GeV Invisible Higgs m>114.3 (113.6) GeV All results still preliminary Fourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001

More Related