Hiroshima Higgs Workshop 2006, Jan. 17 – 19, 2006 Higgs Searches at the Tevatron Kazuhiro Yamamoto (Osaka City University) for the CDF Collaboration 1.Tevatron and CDF 2.SM Higgs 3.MSSM Higgs 4.Future Prospects

Hiroshima Higgs Workshop 2006, Jan. 17 – 19, 2006 Introduction Higgs boson –Last missing brick in the SM –Indispensable for Generating masses of particles Keeping the theory renormalizable at EW scale –Junction piece to the beyond-SM Standard Model (SM) One neutral higgs : h Minimal Supersymmetric Extension of Standard Model (MSSM) Two higgs doublet gives Two neutral CP-even : h, H One neutral CP-odd : A Two charged : H +, H -

Hiroshima Higgs Workshop 2006, Jan. 17 – 19, 2006 Tevatron Accelerator Complex  s = 1.96 TeV # of p and p bunches : 36 x 36 Bunch spacing : 396 ns Recycler as the 2 nd p accumulator Recently implemented new technology : –Slip stacking (MI) –Electron cooling (Recycler) CDF D0 Tevatron Main Injector and Recycler

Hiroshima Higgs Workshop 2006, Jan. 17 – 19, 2006 Tevatron Status Achieving typical luminosity of : –peak : 1.5 ~ 1.7 x cm -2 s -1 –weekly integrated : 15 ~ 20 pb -1 Run II record luminosity : –peak : 1.79 x cm -2 s -1 –weekly integrated : 26 pb -1 Integrated luminosity : –1540 pb -1 delivered –1230 pb -1 on tape –360 pb -1 analyzed ( as of Jan. 2008) World record of hadron collider

Hiroshima Higgs Workshop 2006, Jan. 17 – 19, 2006 CDF II Detector

Hiroshima Higgs Workshop 2006, Jan. 17 – 19, 2006 SM Higgs at the Tevatron pp collision,  s = 1.96TeV Gluon fusion gg  h : 0.7 pb ( M h = 120 GeV/c 2 ) Vector-boson associated production qq’  Wh : 0.16 pb ( M h = 120 GeV/c 2 ) qq  Zh : 0.10 pb ( M h = 120 GeV/c 2 ) Huge QCD background –Need triggering on high- p T leptons from W/Z ’s or higgs

Hiroshima Higgs Workshop 2006, Jan. 17 – 19, 2006 SM Higgs Decay Low mass Higgs (< 130 GeV/c 2 ) –bb dominant  reconstruction of 2 b jets –gg  h  bb swamps on QCD background –Vh production is promising High mass Higgs (130 ~ 200 GeV/c 2 ) –WW dominant  multi-lepton signature

Hiroshima Higgs Workshop 2006, Jan. 17 – 19, 2006 SM Higgs Search at CDF Analysis-ongoing channels 320pb -1 analysis done Analysis in progress 290pb -1 analysis done 360pb -1 analysis done 194pb -1 analysis done

Hiroshima Higgs Workshop 2006, Jan. 17 – 19, 2006 Signature –High p T isolated lepton + missing E T + 2 jets Selection –ISO cal < 0.1p –Missing E T > 20 GeV –2 taggable jets (require 1 or more b-tags) Single b-tag is more sensitive Example of double b-tagged events with large missing E T

Hiroshima Higgs Workshop 2006, Jan. 17 – 19, 2006 Dijet invariant mass in the inclusive single tag sample 95% C.L. upper limits on the WH cross section

Hiroshima Higgs Workshop 2006, Jan. 17 – 19, 2006 Most sensitive channel in Run I and recent analyses at CDF Large missing E T Two jets (at least one b-tag) Selection –1 st jet E T > 40 GeV, 2 nd jet E T > 20 GeV, no other jets w/ E T > 15 GeV –Missing E T > 70 GeV –At least one b-tagged jet Missing E T b-jet y x

Hiroshima Higgs Workshop 2006, Jan. 17 – 19, 2006 Blind analysis on  (Missing E T, 2 nd Jet) and lepton existence Control Region 1 – QCD h. f. Control Region 2 - EWK

Hiroshima Higgs Workshop 2006, Jan. 17 – 19, 2006 Signal Region95% C.L. upper limit on the ZH production Consistent with SM Observed 6 events b/w 80 ~ 120 GeV/c 2 for 120 GeV Higgs.

Hiroshima Higgs Workshop 2006, Jan. 17 – 19, 2006  Large cross section of gluon- fusion and large branching fraction of H  WW at large M H Search for high p T opposite sign dilepton with large missing E T Scalar nature of Higgs results in angular alignment between final state leptons.  Small dilepton invariant mass M H =160GeV/c 2

Hiroshima Higgs Workshop 2006, Jan. 17 – 19, 2006 Binned maximum likelihood method on the  distribution to extract the signal production limit. 95% C.L. upper limit on the Higgs production

Hiroshima Higgs Workshop 2006, Jan. 17 – 19, 2006 Search for like-sign dilepton having at least one high-p T lepton Good signature to discriminate non- Higgs SM events –Most SM events result in opposite sign Understanding fake leptons and conversion electrons was necessary.

Hiroshima Higgs Workshop 2006, Jan. 17 – 19, 2006 Signal search on the p T12 and p T2 plane. –p T12 : vector sum of p T of the leading lepton and the 2 nd leading lepton –p T2 : p T of the 2 nd leading lepton 95% C.L. upper limit on the WH production Update with higher luminosity is ongoing.

Hiroshima Higgs Workshop 2006, Jan. 17 – 19, 2006 Summary of the Cross Section Limits on Higgs Production at the Tevatron Analyses with 200 ~ 300pb -1 data completed. Updates with 500pb -1 ~ 1fb -1 are in progress. Run II goal is 8fb -1.

Hiroshima Higgs Workshop 2006, Jan. 17 – 19, 2006 Limit from indirect measurements Relation among M W, M t, and M H via the radiative correction M W =  GeV/c 2 New result of M t from CDF/D0 : M t =  2.9 GeV/c 2

Hiroshima Higgs Workshop 2006, Jan. 17 – 19, 2006 Limit from indirect measurements (2) EW global fit by LEP EWWGSM or MSSM ? M H < 186 GeV/c 95% C.L. MSSM is favorable for now.

Hiroshima Higgs Workshop 2006, Jan. 17 – 19, 2006 MSSM Higgs at the Tavatron Neutral Higgs at large tan  : –  (= h/H/A ) and  Z production suppressed. –gg/ bb  , gg/ qq’   bb enhanced by ~ (1/cos  ) 2 ~ tan 2 . –Br(    )  10% Br(   bb )  90% in a wide mass range. Charged Higgs –M H + < M t – M b t  H + b –M H + > M t – M b pp  tbH +

Hiroshima Higgs Workshop 2006, Jan. 17 – 19, 2006 MSSM Higgs Search at CDF Analysis-ongoing Channels Analysis in progress 310pb -1 analysis done 192pb -1 analysis done

Hiroshima Higgs Workshop 2006, Jan. 17 – 19, 2006  Selection of  events –One  decays to e or  (  e or   ) –The other  decays to hadrons (  h ) Requirements –E T > 10 GeV, p T > 8GeV/c for e –p T > 10 GeV/c for  –For hadronic  : Isolated narrow jet No tracks b/w 10 o and 30 o from the seed track Jet invariant mass < 1.8GeV/c 2 Opposite electric charge against e or  1 or 3 tracks in the inside cone

Hiroshima Higgs Workshop 2006, Jan. 17 – 19, 2006 Visible mass distribution Calculated 95% C.L. upper limit on the cross section times branching ratio by fitting mass spectrum for Higgs signal. Consistent with SM expectation - 8.4±0.9 expected, 11 observed

Hiroshima Higgs Workshop 2006, Jan. 17 – 19, 2006 Interpret the cross section limit as constraints of M A and tan . Benchmark cases of  0 (+200).

Hiroshima Higgs Workshop 2006, Jan. 17 – 19, 2006 When M H ± < M t + M b, a top quark can decay to a charged higgs. Charged higgs decays to , cs, t*b  Wbb, and Wh(A)  Wbb. This gives discrepancy to SM t  Wb decay ratio.

Hiroshima Higgs Workshop 2006, Jan. 17 – 19, 2006 If a charged higgs exists, anomaly appears in the top cross section and the final state components. 4 channels used for H ± search with 192 pb -1. Observed events Background Expected SM events dilepton 132.7±0.711 lepton + jets (exactly 1 b-tag) ±2.554 lepton + jets ( >=2 b-tags) 80.94± lepton + tau 213±0.22 Latest CDF results No discrepancy to SM

Hiroshima Higgs Workshop 2006, Jan. 17 – 19, 2006 Obtained constraints on the tan  – M H + plane. Two benchmark cases for typical SUSY parameters below: A t = A b =  /tan  A t = A b = sqrt(6)M SUSY +  /tan  M SUSY = 800 GeV/c 2,  = -200 GeV/c 2, A  = 500 GeV/c 2, M 1 = 0.498*M 2, M 2 = 200 GeV/c 2, M 3 = 800 GeV/c 2, M Q = M U = M D = M E = M L = M SUSY Same scenarios as h 0 search by LEP2 (hep-ph/ )

Hiroshima Higgs Workshop 2006, Jan. 17 – 19, 2006 Future Prospects Tevatron upgrade Luminosity is steadily increasing ! Luminosity upgrading plan

Hiroshima Higgs Workshop 2006, Jan. 17 – 19, 2006 Future Prospects (2) Tevatron upgrade (2) We are here ! Red line : Design plan (All technical challenges success) Blue line : Base plan (Simple extrapolation as of the end of FY04) We are on the track of the design plan for now !

Hiroshima Higgs Workshop 2006, Jan. 17 – 19, 2006 Future Prospects (3) SM Higgs Sensitivity Projection For M H = 115 GeV –~2fb -1 for exclusion –~4fb -1 for 3  evidence Assumption –All Higgs channels combined at CDF and D0 –No systematics

Hiroshima Higgs Workshop 2006, Jan. 17 – 19, 2006 Future Prospects (4) MSSM Neutral Higgs Sensitivity Projection Sensitivity for CDF and DO combined. Same techniques and same channels as current analysis assumed. Improvements expected with investigating : –    h  h and  e   – pp   bb  bbbb CDF Run II Preliminary

Hiroshima Higgs Workshop 2006, Jan. 17 – 19, 2006 Conclusions Tevatron luminosity is steadily increasing. –More than 1fb -1 has already been delivered. ~300pb -1 analyses completed. –Data being processed for 1fb -1 challenge. (Planning to show some results in the summer conf. this year.) Obtained some cross section limits on SM and MSSM Higgs bosons. Can we see any signs of Higgs before the LHC ? –Need to do all we can do …

Hiroshima Higgs Workshop 2006, Jan. 17 – 19, 2006 Backup Slides

Hiroshima Higgs Workshop 2006, Jan. 17 – 19, 2006 Improvement WH  l bbZH  bbZH  llbb Mass resolution1.7 Continuous b-bag (NN)1.5 Forward b-tag1.1 Forward leptons Track-only leptons NN selection WH signal in ZH Product of above CDF + D0 combination2.0 All combined