1. 2001-11-23 Tord.Ekelof@tsl.uu.seFourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001 1 MSSM Higgs Searches at LEP Tord Ekelöf Uppsala University Sweden

2. 2001-11-23 Tord.Ekelof@tsl.uu.seFourth 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

3. 2001-11-23 Tord.Ekelof@tsl.uu.seFourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001 3 Introduction SMOne Higgs Field Doublet –One physical Higgs H Production –Higgsstrahlung – Vector boson fusion, small DecayH->bb, , W*W*... MSSMTwo Higgs Field Doublets –Five physical Higgsh 0 A 0 H 0 H + H - Z0Z0 e+e+ e-e- Z0Z0 H0H0 e +, e -, e+e+ e-e- Z,W H0H0

4. 2001-11-23 Tord.Ekelof@tsl.uu.seFourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001 4 –MSSM free parameters M SUSY Sfermion mass parameter at EW scale  SUSY Higgs mass parameter M 2 SU(2) gaugino mass param at EW scale X t Stop mixing term=A t -  tan , A t trilinHt tan  ratio between vacuum expectation values of Higgs field doublets m A A Higgs boson mass m g Gluino mass –On tree level m h calculable from (m A,tan  ) and m h < m z. In one and two loop corrections to production cross-sections and branching ratios all free parameters are involved. Can make m h larger. ~ ~ ~

5. 2001-11-23 Tord.Ekelof@tsl.uu.seFourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001 5 MSSM Higgs production –h 0 Higgsstrahlung,  SM sin 2 (  -  ) Vector boson fusion, small Higgs pair production,  SM cos 2 (  -  ) –A 0 – Higgs pair production,  SM cos 2 (  -  ) h 0 decay if 2m A <m h –H 0 Higgsstrahlung if  large,  SM cos 2 (  -  ) –H + H - Pairproduction e+e+ h0h0 e-e- A0A0 h0h0 Z0Z0 h0h0 Z0Z0 e-e- A0A0 h0h0 Z0Z0 h0h0 Z0Z0 e+e+ h0h0 A0A0 A0A0 e+e+ e-e- e +, e -, Z,W Z0Z0 e+e+ e-e- Z0Z0 h0h0 e+e+ e-e- Z0Z0 H0H0 Z0Z0 e+e+ e-e- Z0Z0 H+H+ H-H-

6. 2001-11-23 Tord.Ekelof@tsl.uu.seFourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001 6 MSSM Higgs decay –h “standard” h 0 ->bb,  +  - invisible, LSP/Majoron h 0 ->  1 0  1 0, JJ fermiophobic, 2HDM type I h 0 ->  flavour independent, MSSM large  h 0 ->cc, ss, gg –A “standard” A 0 ->bb,  +  - bosonic A 0 ->Z 0 h 0 –H +- “standard”, 2HDM if at LEP2 H +- ->cs,  bosonic, 2HDM type I H +- ->W*A 0  - -- -

7. 2001-11-23 Tord.Ekelof@tsl.uu.seFourth 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 Parameter 1. m h max 2. no mixing 3. large  general MSSM scan unit GeV M SUSY 1000 1000 400 200 to 1000  -200 -200 1000 -500 to +500 M 2 200 200 400 200 to 1000 X t =A t -  tan  2M SUSY 0 -300 -2M SUSY to 2M SUSY m g 0.8M SUSY 0.8M SUSY 200 m A 4-1000 4-1000 4-1000 4 to 1000 tan  0.4-50 0.4-50 0.4-50 0.4 to 50

8. 2001-11-23 Tord.Ekelof@tsl.uu.seFourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001 8 1. M h max scenario Designed to maximize the largest h 0 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 h 0 up to a maximal limit m h max < 130 GeV, which depends on the exact value of m top =174.3+-5.1 GeV. 2. No-mixing scenario Same as m h max but with no mixing in the stop sector to see the effect of mixing, m h max <114 GeV 3. Large-  scenario In this scenario h 0 (or H 0 ) does not decay to b quarks in certain parameter-space regions. Motivates flavor independent search. m h max <108 GeV

9. 2001-11-23 Tord.Ekelof@tsl.uu.seFourth 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 sin 2 (  -  ) and different decay BRs e + e - ->hA has cross section proportional to cos 2 (  -  ) with final states bbbb (dominates),  +  - bb and bb  +  -. Cross- section largest when m A  m h. - -- -

10. 2001-11-23 Tord.Ekelof@tsl.uu.seFourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001 10 LEP combined distribution of CL b in the m h max scenario Along the m A  m h diagonal Distribution of confidence (tan  >20, cos 2 (  -  )  1) level in the (m A, m h ) plane

11. 2001-11-23 Tord.Ekelof@tsl.uu.seFourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001 11 LEP combined CL s in the m h max scenario Along the m A  m h diagonal Distribution of exclusion (tan  >20, cos 2 (  -  )  1) in the (m A, m h) plane m A >91.9(95.0) GeV m h >91.0(94.6) GeV observed expected observed expected

12. 2001-11-23 Tord.Ekelof@tsl.uu.seFourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001 12 LEP combined exclusion plots in the m h max scenario in tan  vs m h, m A and m H+ planes excluded region 0.4(0.5)<tan  <2.4(2.6)

13. 2001-11-23 Tord.Ekelof@tsl.uu.seFourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001 13 OPAL Exclusion plots in the m h max scenario in tan  vs m h planes for A, D and O ALEPH DELPHI OPAL m h > 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)

14. 2001-11-23 Tord.Ekelof@tsl.uu.seFourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001 14 LEP combined exclusion for the no mixing scenario in the m A vs m h and the tan  vs m h and m A planes m h >91.5(95.0) m A >92.2(95.3) excluded 0.7(0.8)<tan  <10.5(16.0)

15. 2001-11-23 Tord.Ekelof@tsl.uu.seFourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001 15 OPAL Exclusion plots in the no mixing scenario in tan  vs m h planes for A, D and O ALEPH DELPHI OPAL m h > 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)

16. 2001-11-23 Tord.Ekelof@tsl.uu.seFourth 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 (m H+,  s) and with H + H - decay into cscs, cs  - and  +  -. No prediction for the BR(H+- >  + ). In tree-level MSSM m H+ >m W and m H+ >m A. Search for qqqq, qq  p and  p final states. Use equal masses constraint, acoplanarity, H+ zero spin,  polarization (A,D) and cs identification (D). // - - - - - -

17. 2001-11-23 Tord.Ekelof@tsl.uu.seFourth 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 m H+ <78.0(76.9) 73.8(75.4) 65.6(75.1) 72.2(74.5)

18. 2001-11-23 Tord.Ekelof@tsl.uu.seFourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001 18 1-CL b for charged Higgs, ADO and ALDO and for different BR(H->  )

19. 2001-11-23 Tord.Ekelof@tsl.uu.seFourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001 19 Combimed searches for charged Higgs BR(H->  ) vs H + mass, and cross- section limit m H+ >78.6(78.8) Combined ALDO searches for charged Higgs, mass limit and cross-section limit

20. 2001-11-23 Tord.Ekelof@tsl.uu.seFourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001 20 The L3 charged Higgs excess at 68 Gev

21. 2001-11-23 Tord.Ekelof@tsl.uu.seFourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001 21 Comparison with charged Higgs hadronic decay mass distributions in A, D and O   

22. 2001-11-23 Tord.Ekelof@tsl.uu.seFourth 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 - ->Z 0 H 0, with H 0 ->qq but without imposing requirement on the qq flavour. SM production cross-section and BR(H->had)=1 assumed. - - - - -

23. 2001-11-23 Tord.Ekelof@tsl.uu.seFourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001 23 Flavour-independent search for a neutral Higgs ALEPH m Hinv >109.4(109.8) OPAL m Hinv >101.8(107.3)

24. 2001-11-23 Tord.Ekelof@tsl.uu.seFourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001 24 Higgs decay into photon pairs - fermiophobic Higgs In the MSSM h 0 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, h 0 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. -

25. 2001-11-23 Tord.Ekelof@tsl.uu.seFourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001 25 ALEPH m H >105.4 OPAL m H >105.5 (106.4) L3 (  ) m H >104.3 (104.4) L3 ( ,WW) m H > 104.8 (108.4) Search for Higgs decaying into photon pairs

26. 2001-11-23 Tord.Ekelof@tsl.uu.seFourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001 26 LEP combined data for h° -> 2 

27. 2001-11-23 Tord.Ekelof@tsl.uu.seFourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001 27 Higgs decay to invisible particles e+e+->Z 0 h 0 where Z 0 ->qq or l + l - at SM cross-section h 0 ->  1 0  1 0, lightest neutralinos (R parity cons., LSPs) or h 0 ->JJ, Majorons or h 0 ->other invisible (undetectable) particles, BR=100%. M miss =recoil mass, M vis= visible mass M 2 miss =s-2m Z E vis  s/M vis +m Z 2 -

28. 2001-11-23 Tord.Ekelof@tsl.uu.seFourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001 28 Searches for invisibly decaying Higgs For BR(H->inv.)=100% ALEPH m inv >114.1(112.6) DELPHI m inv >113.0(110.7) OPAL m inv >107.0(107.4) For BR(H->inv.)=any DELPHI m inv =112.7

29. 2001-11-23 Tord.Ekelof@tsl.uu.seFourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001 29 LEP combined data for h°->invisible

30. 2001-11-23 Tord.Ekelof@tsl.uu.seFourth Nordic LHC Physics Workshop Stockholm 22-24 Nov 2001 30 Conclusion NO MSSM/2HDM HIGGS FOUND Combined results of the four LEP experiemnts MSSM m h max m h >91.0 (94.6) GeV All limits at 95% CL m A >91.9 (95.0) GeV 0.5<tan  <2.4 (0.5<tan  <2.6) excluded Charged Higgs m>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