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 ? ?

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  cm -2 s -1 (2003) Projection: 8  cm -2 s -1 (2004) Batavia, Illinois Chicago REACHED 10 Fermilab

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

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/

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.

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.

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.

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

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

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 ± ± ± ±

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) = GeV Lower Mass Limit H ±± (R) = 98.2 GeV H ±± (L) = GeV

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

ICHEP04, Beijing, August 16, 2004 Sudeshna Banerjee 13 Total background 1.1 ± 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 Expected Number 5.8 m H = 100 GeV

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 ± 0.2 Low Mass Region m ll < 80 GeV 0.8 ± ± 0.2 Expected Number m H = 100 GeV

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

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/ ) CDF H L,R ±± Mass limits submitted to Phy. Rev. Lett. in June 2004 (hep-ex/ )

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

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 < Data Candidates pb -1 integrated luminosity used Expected Number GeV 130 GeV mHmH

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 ± ± Mass Limit for Quasi-Stable Doubly charged Higgs is 134 GeV

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