1. Charged Higgs Results from Tevatron Sudeshna Banerjee Tata Institute of Fundamental Research Mumbai, India For CDF and DØ Collaborations Fermilab, Chicago Beijing ICHEP04 Beijing, China Aug 16, 2004  What are Doubly Charged Higgs  How do we look for them at the Tevatron  Did we find them  What can we say about their properties from experimental data  What are Doubly Charged Higgs  How do we look for them at the Tevatron  Did we find them  What can we say about their properties from experimental data ? ?

2. ICHEP04, Beijing, August 16, 2004 Sudeshna Banerjee 2 Main Injector & Recycler Tevatron Booster pp p DØ CDF  p source p pp  s =1.96 TeV  t = 396 ns Luminosity: 4  10 31 cm -2 s -1 (2003) Projection: 8  10 31 cm -2 s -1 (2004) Batavia, Illinois Chicago REACHED 10 Fermilab

3. ICHEP04, Beijing, August 16, 2004 Sudeshna Banerjee 3  Doubly Charged Higgs Bosons appear in several models  L-R Symmetric models, Little Higgs model, MSSM  Higgs fields can be represented as a triplet in L-R symmetric models (along with neutral and singly-charged Higgs)  L-handed and R-handed Higgs fields are possible  In L-R Symmetric models, the Higgs triplets are only one of the Higgs multiplets that break symmetry between L- and R- handed weak interactions at low energy.  SUSY L-R models suggest low mass for a Doubly Charged Higgs (~100 GeV) Properties of Doubly Charged Higgs

4. ICHEP04, Beijing, August 16, 2004 Sudeshna Banerjee 4 Doubly-charged Higgs production cross section is enhanced substantially (~35%) due to NLO corrections. R-handed H++ cross section is smaller by a factor of ~2 due to different value of coupling of these particles to Z bosons. W-W Fusion : q W W H -- ++ q _ Small probability |  EW - 1| Is small, experimentally observed + H ++ q W W - q _ Pair Production : Dominant Production mode Cross section independent of Fermionic coupling  *    H -- q H ++ q _ Production of H ± ± M. Spira & M. Mühlleitner, hep-ph/0305288

5. ICHEP04, Beijing, August 16, 2004 Sudeshna Banerjee 5 A typical decay Couplings like WWH, HHH, HHW and H with hadrons are possible but with very small coupling constants (not considered). Experimental Signature of H ± ± decay A pair of like sign di-leptons (Yukawa coupling >10 -7 )    H -- * *  q H ++  q _ Decay of H ± ± Contamination from other Standard Model processes is low because of the requirement of two high p T leptons of same sign.

6. ICHEP04, Beijing, August 16, 2004 Sudeshna Banerjee 6  Z Z    with charge misidentification, probable for high p T tracks Possible Background Decay Channels Important modes are those which produce like sign leptons semileptonic decays  bb, t t, Z     Hadronic jets leptonic decays  WZ/ZZ one electron radiates a photon which then converts to e + e -, check for photon conversion vertices.  W + jets  Hadronic jets  Cosmic rayseliminated by demanding that the two muons originate at the beam line coincident in time with each other and with a p p collision. e ZZ eliminated by demanding isolated muons.

7. ICHEP04, Beijing, August 16, 2004 Sudeshna Banerjee 7 Search Strategy  Choose events triggered with two high p T dileptons. electron – energetic EM cluster muon – a high p T track matched with a stub in the muon counter + a MIP trace in the EM calorimeter  Make more stringent selection offline.  Generate signal events in different H ±± mass bins covering the search region.  Generate Monte Carlo samples for different background decay channels.  Use the same selection criteria on experimental data, signal and background samples.  If after final selection and background subtraction an excess is seen in experimental data, a discovery is claimed.  If no excess is seen, a limit on H ±± is calculated.

8. ICHEP04, Beijing, August 16, 2004 Sudeshna Banerjee 8 H ±±  channel (100 % BR assumed) Offline selection of events :  Two muons, matched to good tracks (p T > 15 GeV)  Calorimeter E T in outer cone around the muon trace should be small  p T of tracks around the muon track should be small   < 2.51 (requirement for events with less than 3 muons)  Two of the muons should have the same charge Preselection 113 pb -1 integrated luminosity used Search performed by DØ experiment Isolation Acolinearity Like sign requirement Signal Monte Carlo generation (PYTHIA 6.2)  Samples with H ±± mass ranging from 80 GeV to 200 GeV are generated in steps of 10 GeV  Total signal efficiency for the above selection = 47.5 % ± 2.5 %(not mass dependent) All efficiencies derived from data

9. ICHEP04, Beijing, August 16, 2004 Sudeshna Banerjee 9 preselection preselection + like sign muon requirement Z  events dominate Effect of Selection criteria (DØ ) b b events dominate reduces after isolation cut 101 data events 95 b b events

10. ICHEP04, Beijing, August 16, 2004 Sudeshna Banerjee 10 Final Yield (DØ ) like sign requirement preselection isolation acolinearity + + + Signal (mass = 100 GeV) Total background Data preselection isolation acolinearity like sign 9.4 8.5 7.5 6.5 5254 ± 47 4113 ± 43 368 ± 14 1.5 ± 0.4 5168 4133 378 3

11. ICHEP04, Beijing, August 16, 2004 Sudeshna Banerjee 11 Limit calculation depends on mass distribution for signal and background and experimental mass resolution CL (signal) = CL (signal+background)/CL(background ) 95% Systematic Uncertainties – MC (27%), theory (10%), Luminosity (6.5%), normalization (5%) Limit on H ± ± Mass (DØ ) (MCLIMIT - T. Junk, Nucl. Instrum. Methods A 434, 435 (1999)) Lower Mass Limit H ±± (R) = 98.2 GeV H ±± (L) = 118.4 GeV Lower Mass Limit H ±± (R) = 98.2 GeV H ±± (L) = 118.4 GeV

12. ICHEP04, Beijing, August 16, 2004 Sudeshna Banerjee 12 Search for H ± ± (CDF) Acceptance = (Kinematic + geometric) x  trig  ID Leptons are selected in the central   region H ++ Acceptance Search in all dilepton decay channals – e e, e ,    e  242 ± 14 pb -1  e e 235 ± 13 pb -1    240 ± 14 pb -1 Integrated luminosity used

13. ICHEP04, Beijing, August 16, 2004 Sudeshna Banerjee 13 Total background 1.1 ± 0.4 1.5 Observed Events = 1 e e decay channel (CDF) Backgrounds :  Z  e e, one electron radiates a photon which converts to e + e -  Hadronic jets  W + jet  WZ Low Mass Region High Mass Region m ee 80 GeV -0.6 +0.9 Expected Number 5.8 m H = 100 GeV

14. ICHEP04, Beijing, August 16, 2004 Sudeshna Banerjee 14 Total Background (e  ) Di-lepton mass distributions (CDF) Backgrounds : Hadromic jets, W+jet, WZ Total background (   ) Observed Events = 0 High Mass Region m ll > 80 GeV -0.4 +0.5 0.8 0.4 ± 0.2 Low Mass Region m ll < 80 GeV 0.8 ± 0.4 0.4 ± 0.2 Expected Number m H = 100 GeV 10.1 5.0

15. ICHEP04, Beijing, August 16, 2004 Sudeshna Banerjee 15 No events are found in the high mass regions of e e, e ,   samples. Limit on Higgs mass is calculated using Bayesian method with flat prior for signal and Gaussian prior for background and acceptance uncertainties. Limit Calculation (CDF) H+ +H+ + (R)  H+ +H+ + (L)  (e e = 133, e  = 115,  = 136) GeV (  = 115) GeV

16. ICHEP04, Beijing, August 16, 2004 Sudeshna Banerjee 16 Promptly Decaying H ±± Summary of mass limits D Ø H L,R ±± Mass limits submitted to Phys. Rev. Lett. in April 2004 (hep-ex/0404015) CDF H L,R ±± Mass limits submitted to Phy. Rev. Lett. in June 2004 (hep-ex/0406073)

17. ICHEP04, Beijing, August 16, 2004 Sudeshna Banerjee 17  No constraint on the lifetime of H ±±, can be long  Search for particles with c  > 3 m, no decay within the detector  They will behave like heavy stable particles, (muons but more ionising) Measurement of ionization – dE/dx measurement along the charged particle track in tracker and calorimeter. Background – Advantage is lack of Standard Model decays. Events expected from highly ionizing particles. Muons – data from cosmic rays (pure muon sample) Electrons – W e  Monte Carlo sample Hadronic decays for taus from Monte Carlo sample QCD contribution calculated from experimental data Long Lived Doubly Charged Higgs (CDF)  Main process of energy loss is ionization, dE/dx  (charge) 2

18. ICHEP04, Beijing, August 16, 2004 Sudeshna Banerjee 18  Tracker dE/dx >35 ns Loose cut : Tight cut :  Energy (EM) > 0.6 GeV  Energy (Had.) > 4 GeV Select events which have a good muon track with p T > 18 GeV. Require a second track with p T > 20 GeV offline. Long Lived Doubly Charged Higgs (CDF) Use loose cuts for setting mass limits And tight cuts for discovery. Loose Search Tight Search Total Background < 10 -5 10 -6 Data Candidates 0 0 206 pb -1 integrated luminosity used Expected Number 10.26.6 3.2 2.4 100 GeV 130 GeV mHmH

19. ICHEP04, Beijing, August 16, 2004 Sudeshna Banerjee 19 Mass Limit for Long Lived Higgs Bayesian upper limit on H ±± crosssection  H ±± Upper Limit on No. of Signal Events at 95% C.L. for 0 Observed Events Total H ±± Acceptance x Integrated Luminosity = For a H ±± mass of 130 GeV H ±± cross section is 0.057 ± 0.0066 ± 0.0030 Mass Limit for Quasi-Stable Doubly charged Higgs is 134 GeV

20. ICHEP04, Beijing, August 16, 2004 Sudeshna Banerjee 20 Tevatron has improved the limits on masses of H ±± There is scope for much more improvement in the coming years Tevatron has improved the limits on masses of H ±± There is scope for much more improvement in the coming years Conclusions Prompt Decays Limits on L-handed Higgs have gone up to ~ 130 GeV Limits on R-handed Higgs have gone up to ~ 113 GeV DØ plans to include e e and e  modes in future. Long Lived Higgs Limit on Higgs mass is 134 GeV Both experiments will redo the analyses with much more luminosity as good data is being collected at a steady rate at the Tevatron. LEP Results For both promptly decaying and long lived Higgs Mass Limit ~ 100 GeV Tevatron Results