Search for Charged Higgs Bosons at the Tevatron =============================================== Christian Schwanenberger 1) Title 2) Motivation for Top Quark physics 3) The top discovery was made only with a hand full of events. 4) Today we have several thousand top quark candidates in our analysis samples. 5) We can perform precision measurements such as the top quark mass measurement. 6) We can also perform sensitive searches for new physics beyond the SM. 7) The LHC will be a top factory: we look into a bright future of top quark physics, 8) The Tevatron collider 9) Top analyses overview at the Tevatron 10) In this talk we concentrate on searches for charged Higgs bosons 13) Top pair production modes 14) Top pair decay channels 15) Signal and backgrounds for the l+jets channel. Signal is taken from MC simulations. For the W+jets background we can only take the shape from the MC. Multijets background is taken from data. 16) Summary of top pair cross section measurements in different channels. All agree with each other and with the SM prediction. At this point NNLO calculations are needed from theory to get to a similar error than experiments. 17) Overview about single top production mechanisms and display of a candidate event. 18) Summary of single top observation, cross section measurements of CDF and D0 and the Tevatron combination for cross section and the CKM matrix element |Vtb| 19) The same technique which allowed to extract the single top production signal out of a huge W+jets background can, in principle, be used to discover associated Higgs production as well. 20) It also allows to search for charged Higgs bosons decaying into a top and a bottom quark 22) There was no evidence for charged Higgs bosons decaying into top and b quarks. Reconstructing the charged Higgs mass, one was able to exclude a region in tan(beta) and M_H+ in a Type I 2HDM. 24) Lighter charged Higgs bosons can be searched for in top quark decays. In the MSSM the branching ratios for such decays are enhanced for high and low tan(beta). MC simulations for the decay H+ -> t* bbar are currently missing! 25) We use the combination of ttbar cross section measurements in the l+jets, dilepton and tau+lepton final states to search for charged Higgs bosons. 26) Hadronically decaying charged Higgs bosons (shown are branching fractions of 30% and 60%) would lead to a decrease in the number of events in all channels. The data favors the SM. 27) Same as 25). 28) Tauonically decaying charged Higgs bosons (shown are branching fractions of 30% and 60%) would lead to a decrease in the number of events in the l+jets and dilepton channels but to an increase in the tau+lepton final state. The data favor the SM. 29) ttbar cross section ratios are used for searches for charged Higgs bosons in top decays. Since many uncertainties such as the luminosity uncertainty cancel, this is an attractive analysis for early LHC data. 30) Upper limits on t -> H+ b branching ratios are derived for leptophobic and tauonic charged Higgs bosons. 31) Leptophobic charged Higgs bosons are searched for using the invariant dijet mass to reconstruct the H+ mass. Upper limits on the branching ratio are derived. 32) Topological information is combined into a multivariate discriminant to separate between ttbar and other backgrounds. The output discriminant shows that ttbar is enhanced at large values of the discriminant while the other background peaks at low values. 33) The existence of a charged Higgs boson would lead to a disappearance of events in the l+jets channel - and be visible in the Likelihood discriminant. Clearly the data prefer the SM. 34) An upper limit on the t -> H+ b branching ratio is derived for the m_h^max MSSM benchmark scenario. 35) Performing a global fit to the ttbar cross section measured in all different channels which are used for the cross section combination the sensitivity to charged Higgs bosons is enhanced. No hint for a deviation from the SM prediction is found. 36) Upper limits on the t -> H+ b branching ratio are derived assuming a purely tauonic, a purely leptophobic or a mixture of different fractions of tauonic and leptophobic Higgs decays. 37) The measurement is systematically limited. The largest sources for systematic uncertainties are due to the ttbar cross section and luminosity error. 38) For the purely tauonic H+ decay a simultaneous fit to the t -> H+ b branching ratio and to the ttbar cross section reduces the uncertainties considerably. The gain in sensitivity is approximately 20%. 40) For purely leptophobic charged Higgs decays, excluded regions as a function of tan(beta) and M_H+ are given. MHDMs could provide an explanation of such a scenario. 41) For purely tauonic charged Higgs bosons we give excluded regions as a function of tan(beta) and M_H+ for 2 MSSM benchmark scenarios: no-mixing and m_h^max-scenario. 42) In a CPX benchmark scenario it can be achieved, that the whole Higgs sector is strangephilic in a narrow region for high tan(beta). 43) Since all Tevatron searches for the neutral Higgs boson rely on either b-tagging or tau identification, they would miss a strangephilic neutral Higgs boson where H -> s sbar is dominating. If nature had realized such a scenario, one could only find the charged Higgs easily. 44) The excluded regions in this strangephilic CPX benchmark scenario as a function of tan(beta) and M_H+ is given. The charged Higgs boson decays - dependent on tan(beta) - either hadronically or tauonically. 45) In this particular scenario, around tan(beta)=38 the Higgs sector is strangephilic with a close to 100% branching ratio B -> c sbar. The limits represent the first Tevatron H+ limits on a CP-violating MSSM scenario. 47) Conclusion: there are still many ways to improve charged Higgs analyses at the Tevatron in the future: add data, add more decay channels, include topological information about the charged Higgs boson into the analyses. Furthermore, more interesting SUSY models should be tested. The results will be combined with MSSM searches for neutral Higgs bosons at the Tevatron.