1. Pamela Ferrari0 0 Recontres de Moriond ‘05 QCD and Hadronic interactions QCD and Hadronic interactions Recontres de Moriond-La Thuille 12-19 March 2005 Searches for Higgs in the MSSM CP-conserving and CP-violating scenarios at LEP P.Ferrari (CERN) on behalf of the LEP experiments -model introduction -the CP-conserving MSSM -the CP-violating MSSM -2HDM

2. Pamela Ferrari1 1 Recontres de Moriond ‘05 2 Higgs Doublet Models Simplest extension of SM are 2HDMs and no FCNC Two complex scalar field doublets Φ 1 and Φ 2, 5 scalar Higgses: - Real parts mix with  -> CP even scalars h 0,H 0 - Imaginary part -> CP odd scalar A 0 - Two charged scalars H +- Two production processes :  hZ =sin 2 (  )  SM HZ  HZ =cos 2 (  )  SM HZ  HA =cos 2 (  )  SM HZ  =ratio of VEV of scalar fields The type of 2HDM determined by the couplings of Φ 1, Φ 2 to fermions: - Only  1 couples to fermions 2HDM (I) -  1 (  2 ) couples to down (up) type fermions 2HDM(II) Z0Z0 e-e- e+e+ Z*Z* h,H A0A0 e-e- Z*Z* h e+e+ Higgsstrahlung Pair-Production

3. Pamela Ferrari2 2 Recontres de Moriond ‘05 The MSSM 2HDM(II) are interesting since by adding supesymmetry CP-conserving MSSM CP-conserving MSSM is interesting since it provides framework for unification of Gauge interactions and stability of universe at EW scale m h <140 GeV after radiative corrections to explain matter-antimatter asymmetry in universe we need CP-violation >> than in SM Justifies introduction of CP-violation in MSSM: can be done via radiative corrections (in particular from 3 rd generation s-quarks)

4. Pamela Ferrari3 3 Recontres de Moriond ‘05 CP-violation in MSSM Mass eigenstates and CP-eigenstates do not coincide: H 1,H 2,H 3 are mixtures of CP-even and CP-odd Higgs fields Only CP eigenstates h,H can couple to Z But H 1 is the propagating particle Lightest Higgs boson might have escaped detection at LEP2: H 1 might decouple almost completely from the Z Search for both H 1 Z and H 2 Z production

5. Pamela Ferrari4 4 Recontres de Moriond ‘05 Experimental searches b-tagging HZ (H  bb) (Z  qq ) (H  bb,  )  ( Z   ) (H  bb,qq) (Z  ee  (H   )  ( Z  qq), (H  bb,  )  ( Z   ) Flavour independent HZ (H  qq) Z (H 2  H 1 H 1  ) Z dominant when kinematically allowed b-tagging pair production H 2 H 1 (H 2  bb) (H 1  bb ) (H 2   )  (H 1  bb ) (H 2  H 1 H 1  bbbb )((H 1  bb ) Flavour independent H 2 H 1 used only for 2HDM(II) scan (H 2  qq) (H 1  qq ) Additional constraints Z width, decay mode independent search for HZ, light Higgs from Yukawa production ALEPH, DELPHI, OPAL & L3 data @ 91 GeV<  s< 209 GeV Interpreted in MSSM CPC and CPV and 2HDM(II)

6. Pamela Ferrari5 5 Recontres de Moriond ‘05 MSSM CPC benchmarks MSSM CPC benchmarks - No mixing ( 2TeV) reversed  sign motivated by (g-2)  - m h -max+ with reversed  sign motivated by (g-2)  - constrained m h -max reversed sign for A t and X t motivated by Br(b->s  ) - gluophobic gg->h suppressed - small  eff h->bb,  suppressed 7 parameters: (Carena et al. hep-ph/9912223) m top = 179.3 GeV ( 178.0  4.3 GeV CDF & D0) M SUSY sfermion mass at EW scale  Higgs mixing parameter M 2 gaugino mass at EW scale m g gluino mass X t = Stop mixing parameter A b =A t = Xt +  cot  trilinear Higgs-squark coupling Traditional scans: - No mixing: in stop sector - m h max: yields maximal bound on m h TH - Large  : suppressed h-> bb Regions where Hadron colliders might have problems in detecting the Higgs Favoured by (g-2)  and Br(b->s  ) New scans: envisaged for final LEP combination but not yet done

7. Pamela Ferrari6 6 Recontres de Moriond ‘05 CPC m h -max scan 2 calculations used:  FeynHiggs 2.0: 2-loop diagrammatic approach & OS scheme S.Heinemeyer et al. hep-ph/0212037  SUBHPOLE: 1-loop renormalization group, scheme M.Carena et al hep-ph/9912223 FeynHiggs is chosen: more accurate, conservative results LHWG-Note/2004-01 m h (GeV/c 2 ) m A (GeV/c 2 ) tan  Obs92.994.80.9-1.5 Exp94.895.10.8-1.6 Expected exclusion

8. Pamela Ferrari7 7 Recontres de Moriond ‘05 No-mixing & large  scans No-mixing & large  scans Large  No-mixing 0.37<1-CL b <0.65 Nearly excluded LHWG-Note/2004-01 m h (GeV/c 2 ) m A (GeV/c 2 ) tan  Obs93.393.30.4-5.6 Exp95.095.00.4-6.5 For m h ~80 GeV and tan  <0.7, m A <  threshold: A decays uncertain h  bb small No-mixing

9. Pamela Ferrari8 8 Recontres de Moriond ‘05 Did we miss the Higgs? No excess larger than 3   2  @ m h ~98 GeV  2  @ m h ~115 GeV. Recent interpretations: M.Drees hep-ph/0502075 G.L. Kane et al. hep-ph/0407001 Explain this kind of “excess” within  CP-conserving MSSM  CP-violating MSSM  2HDM LHWG-Note/2004-01

10. Pamela Ferrari9 9 Recontres de Moriond ‘05 Example of new scans Example of new scans OPAL Eur.Phys.J.C37:49-78,2004 Only OPAL data: exclusion will be larger for LEP combination Large regions of the parameters space are excluded

11. Pamela Ferrari10Pamela Ferrari10 Recontres de Moriond ‘05 Phases of A t,A b and m g introduce CP violation in the Higgs potential via loop effects leading off-diagonal contributions to higgs mass matrix CP-violating MSSM CP-violating MSSM Theoretically: argA u ≠0 most general case, can be motivated by Baryogenesis. Size of CP violating effects proportional to: benchmark: large argA u ≠0, large , relatively small m SUSY the CP violation increases with m t ~ ~

12. Pamela Ferrari11Pamela Ferrari11 Recontres de Moriond ‘05 CPX benchmark tan  m H +( GeV)  (GeV) m SUSY (GeV) M 2 (GeV) |A q | (TeV) arg(A q ) m g (TeV) arg(m g ) 0.6–404–100020005002001 90 o 1 Maximal CP violation EDM measurements of n and e fullfilled Feynhiggs and CPH are a priori equivalent: Feynhiggs has more advanced one-loop corrections CPH (CPV version of SUBHPOLE) is more precise at the two-loop level In each parameter space point the most conservative result is used All implemented in HZHA with ISR and interference between identical final states from Higgstrahlung and boson fusion process Carena et al., Phys.Lett B495 155(2000)

13. Pamela Ferrari12Pamela Ferrari12 Recontres de Moriond ‘05 CPX scan m t (GeV/c 2 ) Expected tan  Observed tan  174.3>2.9>3.0 179.3>2.6>2.7 183.0>2.5>2.5 No lower m H 1,2 limit m t dependent 95%CL on tan  : LHWG-Note/2004-01 m t =178.0  4.3 GeV CDF & D0 For heavy H 2 :  H 1  H SM  m H 1 > 115 GeV ~

14. Pamela Ferrari13Pamela Ferrari13 Recontres de Moriond ‘05 CPX scan LHWG-Note/2004-01 Strong reduction of exclusion increasing m t  CP-violation: for example 4<tan  <10, where both H 1 Z & H 2 Z are open No excess larger than 3  found

15. Pamela Ferrari14Pamela Ferrari14 Recontres de Moriond ‘05 Signal generated with HZHA Free parameters: 1 < m h < 130 GeV 1 < m h < 130 GeV 3 GeV <m A < 2 TeV 3 GeV <m A < 2 TeV  /2,   /4,0 0.4< tan  <40 0.4< tan  <40 m H and m H  kinematically unaccessible Excluded rectangular region for 1<m h <55 GeV when 3<m A <63 GeV But for m A > 63 values of m h down to 0 are still allowed ! No tan  exclusion independent of m h /m A OPAL general 2HDM(II) scan 2HDM(II) have no constraint derived from SUSY: h  bb is not dominant decay,e.g for  =0 BR(h  bb/  )=0  flavour-indep. searches h  bb is not dominant decay,e.g for  =0 BR(h  bb/  )=0  flavour-indep. searches large regions of the parameter space cannot be exlcuded by LEP large regions of the parameter space cannot be exlcuded by LEP light Higgs not ruled out hep-ex/0408097

16. Pamela Ferrari15Pamela Ferrari15 Recontres de Moriond ‘05 Conclusions At LEP we have searched for Higgses in several extensions of SM: CP-conserving MSSM CP-violating MSSM 2HDM No evidence of the presence of a signal has been found Still there is room for the presence of a light Higgs: In CP-violating MSSM In 2HDMs In 2HDMs Some theoretical papers interpreting small data-background discrepancy (about 2  ) in the context of specific CPC MSSM scenarios ( require quite some tuning) as well as CPV MSSM and 2HMD.

17. Pamela Ferrari16Pamela Ferrari16 Recontres de Moriond ‘05 Back-up

18. Pamela Ferrari17Pamela Ferrari17 Recontres de Moriond ‘05 SM vs MSSM excess The excesses at m h =98 & 115 GeV Observed in MSSM are the same that where observed in the SM searches: m h ~98 GeV 2.3  excess 1-CL b = 2% from all hZ channels Not Compatible with a SM signal. m h ~115 GeV 1.7  excess 1-CL b = 9% from ALEPH hZ 4-jet channel Compatible with a SM signal. 1-CL b gioves the Probability of a local fluctuation of background. Probability that a fluctuation appears anywhere within a certain mass range is given by:

19. Pamela Ferrari18Pamela Ferrari18 Recontres de Moriond ‘05 m h max scans m h max scans m t =174.3,179,183 GeV

20. Pamela Ferrari19Pamela Ferrari19 Recontres de Moriond ‘05 No-mixing

21. Pamela Ferrari20Pamela Ferrari20 Recontres de Moriond ‘05 Useful searches for CPV MSSM

22. Pamela Ferrari21Pamela Ferrari21 Recontres de Moriond ‘05 CPH vs FEYNHIGGS  The largest discrepancy occurs for large tan  where Feynhiggs predicts a higher x-section for Higgstrahlung  Data/background discrepancy in intemediate tan  region: due to excess at m h ~98 GeV which is the m H 2 mass in this region

23. Pamela Ferrari22Pamela Ferrari22 Recontres de Moriond ‘05 CPX-phases Exclusion decreases With increasing argA t,b (CP-Violation)

24. Pamela Ferrari23Pamela Ferrari23 Recontres de Moriond ‘05 2HDM scan

25. Pamela Ferrari24Pamela Ferrari24 Recontres de Moriond ‘05 2HDM scan tan  exclusion No tan  exclusion independent from m h and m A

26. Pamela Ferrari25Pamela Ferrari25 Recontres de Moriond ‘05