Review of MSSM Higgs boson searches at LEP

Review of MSSM Higgs boson searches at LEP Vanina Ruhlmann-Kleider CEA/DAPNIA/SPP 1) 2) 3) Physics at LHC 2006 MSSM with CP conservation MSSM with CP violation Conclusions 3 July 2006 1

CP-conserving MSSM scenarios 3 neutral Higgs bosons: h, H, A at tree level, 2 parameters : h. Z: low tan large tan & m. A CP-eigenstates tan , m. A h. A: interm. /large tan & low m. A HZ: large tan & low m. A Higgs decays: invisible, , ee, , , KK, cc, , bb, AA, hadrons Physics at LHC 2006 3 July 2006 2

The MSSM underlying parameters at higher order mtop and the SUSY breaking parameters, assumed to be unified at some scale : SU(2), U(1) gaugino mass terms unified at MGUT sfermion mass terms : unified at MEW squark trilinear couplings : unified at MEW mixing parameter in the stop sector : gluino mass and Higgs mixing parameter M 2 at MEW Msusy at MEW A at MEW X = A - cot Mğ and Total: 8 parameters mtop is measured ; M 2, Msusy, Mğ, et X are chosen to define a “scenario”; tan and m. A are free to vary (tan [0. 4, 50] and m. A [0. 02, 1000] Ge. V). NB: radiative corrections in the Feynman-diagrammatic approach (the most complete at two-loop order) Physics at LHC 2006 3 July 2006 3

The scenarios : 3 LEP / 5 LHC scenarios o o mhmax: sparticules at high mass (M 2, Msusy, Mğ large), et X such that mh range is maximal (mtop=174. 3 Ge. V: mh < 132. 9 Ge. V). LHC variants: 1) - , 2) - & X -X No mixing: counterpart of mhmax with X=0; mh range reduced (mtop=174. 3 Ge. V: mh < 115. 5 Ge. V). LHC variant: 1) - , Msusy 2 Msusy o Large : at least one Higgs (h, A or H) kinematically accessible (mtop=174. 3 Ge. V: mh < 108. 0 Ge. V) but Br(bb, ) vanish at large tan. o Gluophobic scenario: gg h (strongly) suppressed tan , m. A o Small eff : Brh(bb, ) suppressed at large tan , moderate m. A Physics at LHC 2006 3 July 2006 4

The mhmax scenario(s) mtop 95%CL 99. 7%CL mtop=174. 3 Ge. V, 95% CL limits: mh > 92. 8 Ge. V, m. A > 93. 4 Ge. V insensitive to mtop tan exclusion : 0. 7 – 2. 0 sensitive to mtop LHC variants: ~identical mass limits, looser tan constraints Physics at LHC 2006 3 July 2006 5

The no mixing scenario(s) unexcluded holes: h AA, m. A<3 Ge. V, mh~80 Ge. V lack of searches at LEP 2 mtop=174. 3 Ge. V, 95% CL limits: mh, m. A > 93. 6 Ge. V (tan >0. 7) tan exclusion : 0. 4 – 10. 2 (m. A>3 Ge. V) very sensitive to mtop: scenario fully excluded at mtop=169. 3 Ge. V (H within reach) LHC Physics at LHC 2006 variant: tighter mass 3 July and 2006 tan limits 6

The large scenario excluded at 95% CL, not at 99. 7% CL: o h. Z only remaining process o BR(h bb) suppressed o mh~108 Ge. V close to the sensitivity of the flavour-blind searches This strip grows with increasing mtop theoretically forbidden mtop=174. 3 Ge. V or smaller: scenario fully excluded at 95%CL thanks to: H searches and flavour-blind analyses Physics at LHC 2006 3 July 2006 7

The gluophobic and small scenarios mtop=174. 3 Ge. V , 95% CL limits: mh > 90. 5 Ge. V, m. A > 96. 3 Ge. V mh > 87. 3 Ge. V, m. A > 98. 8 Ge. V tan exclusion : 0. 4 – 5. 4 tan exclusion : 0. 4 – 4. 2 moderately sensitive to mtop Physics at LHCNB: 2006 h, A not degenerate 3 in. July mass 2006 at large tan 8

CP-conserving MSSM scenarios, conclusions: o o 8 representative scenarios scanned with ADLO results on neutral Higgs boson searches at LEP 1 & LEP 2 ; improved sensivity thanks to H searches and flavour-blind analyses (esp. for low mtop) o mass limits are set at large tan and ~ O(90) Ge. V in mh, m. A o tan limits are set by the LEP mhmax scenario : tan exclusion (95%CL) : 0. 7 – 2. 0 for mtop=174. 3 Ge. V Physics at LHC 2006 3 July 2006 9

CP-violating MSSM scenarios 3 neutral Higgs bosons: H 1, H 2, H 3 mixtures of CP-eigenstates at tree level, 2 parameters : tan , m. H H 1 Z: low tan , large tan & m. H 1 H 2: interm. /large tan & low m. H 1 H 2 Z: low/interm. tan & low m. H 1 wrt CPC case: more processes a priori, but some ZZHi couplings can be suppressed similar decays, but Hj Hi. Hi is enhanced Physics at LHC 2006 3 July 2006 10

The MSSM underlying parameters o The usual eight MSSM underlying parameters : • at tree level : tan , m. H± • through radiative corrections : mtop and the SUSY breaking parameters: M 2, Msusy, Mğ, and At, b o Additional CPV parameters : • two CPV phases : arg(At, b) and arg(Mğ) Dominant CPV effects scale as: mtop 4 Im( At, b)/(v 12+v 22)32 2 Msusy 2 low Msusy, large and arg(At, b)~90 o the CPX scenario: Msusy=500 Ge. V, =4 Msusy=2 Te. V, |At, b|=Mğ=2 Msusy=1 Te. V, M 2=200 Ge. V and arg(At, b)=arg(Mğ)=90 o o + 10 variants to study the dependence with arg(At, b), and Msusy. NB: radiative corrections in the renormalization group and Feynman-diagrammatic approaches (presently at the same stage 3 of. July developpement) Physics at LHC 2006 11

CPC ! 60° Dependence with the CP -violating phases 0° 90° Phases ~90°: H 1 Z suppressed large tan : H 1 H 2 interm. tan : H 2 Z, esp. H 2 H 1 H 1 Physics at LHC 2006 slight excess of data lack of sensitivity 3 July 2006 12

2 Te. V Dependence with 1 Te. V 4 Te. V At intermediate tan : =1 Te. V: two processes left =2 Te. V: one process left =4 Te. V: no process left Physics at LHC 2006 3 July 2006 13

174. 3 Ge. V Dependence with mtop 169. 2 Ge. V 179. 4 Ge. V At intermediate tan : H 1 Z, H 2 Z and H 1 H 2 suppression gets stronger with increasing mtop Physics at LHC 2006 3 July 2006 14

CP-violating MSSM scenarios, conclusions: o o 11 representative scenarios scanned with ADLO results on neutral Higgs boson searches at LEP 1 & LEP 2 ; Significant effects require arg(At, b)=90°, 135°, mtop 174 Ge. V, and |At, b|/ Msusy 2 8 ; CPV = redundancy lost reduced sensitivity of LEP at intermediate tan down to the lowest masses No absolute mass limits ! tan limits are set by the CPX scenario : tan > 2. 9 (95% CL) for mtop=174. 3 Ge. V o Results are qualitatively the same in the renormalization group and Feynman-diagrammatic approaches. Physics at LHC 2006 3 July 2006 15

Conclusions From the neutral Higgs boson searches at LEP applied to a set of representative MSSM scenarios : o If CP is conserved in the Higgs sector: • absolute mass limits around 90 Ge. V in mh, m. A ; • low tan region not favoured (0. 7 – 2. 0 excluded in the LEP mhmax scenario for mtop=174. 3 Ge. V). o If CP is not conserved in the Higgs sector: • No absolute mass limits (at intermediate tan ) ! • low tan region still not favoured (tan <2. 9 excluded in the CPX scenario for mtop=174. 3 Ge. V); • Calculations of radiative corrections not yet as complete as in the CP -conserving case. Physics at LHC 2006 3 July 2006 16

Higgsstrahlung Introduction o Higgs boson searches at LEP: Direct searches : Pair-production • Only 3 production processes • Almost all decays can be exploited (+ WW, ZZ fusion) • model-independent constraints on x Br • model scans : SM, MSSM, 2 HDM Yukawa production o Indirect constraints through EW precision measurements In this talk: SM + MSSM neutral Higgs boson direct searches published in April 2006 Physics at LHC 2006 3 July 2006 17

Current summary about the SM Higgs boson: Direct searches : MH ≥ 114. 4 Ge. V (95% CL) MH [115, 118] Ge. V ? Physics at LHC 2006 EW precise measurements: MH ≤ 175 Ge. V (95% CL) (status as of spring 2006) 3 July 2006 18

The Standard Model after LEP results: Physics at LHC 2006 New physics scale 3 July 2006 19

95% CL upper bounds on x Br H 1 Z dominant decays : direct decays in bb or Physics at LHC 2006 3 July 2006 H 2 H 1 20

95% CL upper bounds on x Br non dominant decays : the example of the H 2 H 1 H 1 cascade H 2 Z Physics at LHC 2006 H 2 H 1 3 July 2006 21

The gluophobic and small scenarios gluo. scen. Br(MSSM)/ Br(SM) predictions NB: tth ttbb and WW fusion channels enhanced Physics at LHC 2006 small NB: h channel unsuppressed 3 July 2006 22

CPH vs Feyn. Higgs weaker exclusion more one-loop and two-loop order corrections in Feyn. Higgs phase dependence more complete in CPH than in Feyn. Higgs Physics at LHC 2006 3 July 2006 23