Bulletin of the American Physical Society
2009 APS April Meeting
Volume 54, Number 4
Saturday–Tuesday, May 2–5, 2009; Denver, Colorado
Session W9: Top and Higgs Physics |
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Sponsoring Units: DPF Chair: Raymond Brock, Michigan State University Room: Governor's Square 11 |
Tuesday, May 5, 2009 10:45AM - 10:57AM |
W9.00001: Search for non-standard model top antitop resonance production in the all-hadronic channel at CDF Yuri Oksuzian We present an updated result of a search for resonant top-antitop pair production and subsequent decay in the all-hadronic channel. We examine the top-antitop invariant mass spectrum observed in CDF data from 1.96 TeV $p\overline p$ collisions at the Fermilab Tevatron. We apply a powerful reconstruction technique where the observed event kinematics are constrained according to the full standard model top-antitop production and decay matrix element. This technique provides excellent mass resolution. Also, probability densities from the per-event matrix element calculation are used as discriminants to reduce and control the large backgrounds of the all-hadronic channel. [Preview Abstract] |
Tuesday, May 5, 2009 10:57AM - 11:09AM |
W9.00002: Search for Charged Higgs Bosons in Decays of Top Quarks Diego Menezes We present a search for charged Higgs bosons in the mass range $80 < m_{H^{\pm}} < 155$~GeV, assuming the decay $H^{+} \rightarrow \tau^{+} \nu_\tau$ (and its charge conjugate). Using 0.9~fb$^{-1}$ of lepton+jets data collected by the D0 detector, at the Fermilab Tevatron $p\bar{p}$ collider, we find no evidence for signal, and exclude branching ratios $B(t \rightarrow H^+b)$ at $95\%$ confidence level. [Preview Abstract] |
Tuesday, May 5, 2009 11:09AM - 11:21AM |
W9.00003: Search for Neutral Supersymmetric Higgs Bosons in bbb(b) Final States in $p\bar{p}$ Collisions at $\sqrt{s}$=1.96 TeV Prolay Mal We present a search for Higgs bosons in the bh($\to$bbar) and bbh($\to$bbar) channels at a center-of-mass energy of $\sqrt{s}=$1.96~TeV using up to 4~fb$^{-1}$ of data collected with the D0 detector. In many supersymmetric models the cross section for production of neutral Higgs bosons in association with bottom quarks is greatly enhanced compared to the Standard Model, and over much of the parameter space the dominant decay process is $\to bbar$. We search for an excess of events above the multijet background in events with 3 and 4 $b$-jets. Understanding the multijet background in this channel is particularly challenging. [Preview Abstract] |
Tuesday, May 5, 2009 11:21AM - 11:33AM |
W9.00004: Measurement of the $W$ boson helicity fractions in $t\overline{t}$ production in dilepton channel at CDF Roman Lysak We analyze $W$ boson helicity fractions of $t\overline{t}$ candidates selected from final states where both $W$ bosons are decaying leptonically. The analysis is based on 3~fb$^{-1}$ of data collected with the CDF detector at the Tevatron. The $W$ helicity fractions are determined by a comparison of angular distributions of leptons in the $W$ rest-frame with templates corresponding to left-handed, right-handed and longitudinal fractions exclusively. This is the first measurement of $W$ helicity fractions in this channel using kinematic reconstruction at CDF. [Preview Abstract] |
Tuesday, May 5, 2009 11:33AM - 11:45AM |
W9.00005: Measurement of forward-backward asymmetry in top quark production at CDF Glenn Strycker We measure a forward-backward charge asymmetry in the rapidities of top quarks produced in $p\bar p$ collisions at $\sqrt s$=1.96 TeV. The $t\bar t$ kinematics are reconstructed in ~800 lepton+jets events collected in a 3 $fb^{-1}$ exposure with CDF detector at Fermilab. We present two independent techniques -- a model independent unfold and a likelihood fit to a linear asymmetry in the production angle $(1+Acos(\alpha))$ -- that give consistent results for the parton level asymmetry in both the laboratory and $t\bar t$ rest frames. The results are compared to the small charge asymmetry expected in QCD at NLO. [Preview Abstract] |
Tuesday, May 5, 2009 11:45AM - 11:57AM |
W9.00006: Measurement of The Top Quark Electric Charge Jeong Ku Lim In the Standard Model, the decay of the top quark: $t \to b W^+$ gives an electric charge of $2/3$ for the top quark. However the decay $t \to \bar{b}W^+$ does not violate any fundamental laws and it predicts a top quark charge of $4/3$. We provide a measurement of the electric charge of the top quark using $t \bar{t}$ events in the lepton + 4 jets final state using events 4~$fb^{-1}$ of D0 data. [Preview Abstract] |
Tuesday, May 5, 2009 11:57AM - 12:09PM |
W9.00007: Search for a Light NMSSM Higgs Boson at CDF Scott Wilbur We present a search for an NMSSM Higgs boson as proposed by Dermisek and Gunion [1]. This model invokes a light Higgs with a mass of order 100~GeV/$c^2$, which decays into two CP-odd Higgs bosons with $m_a < 2m_b$. This CP-odd Higgs is expected to decay principally into two $\tau$ leptons, leaving a four-$\tau$ final state. This decay chain evades the LEP limit of $m_H > 114$~GeV/$c^2$ and is well motivated by the LEP data. \\[4pt] [1] Dermisek, Gunion Phys. Rev. D75, 075019 (2007) [Preview Abstract] |
Tuesday, May 5, 2009 12:09PM - 12:21PM |
W9.00008: Search for Neutral Supersymmetric Higgs Bosons in b$\tau\tau$ Final States in $p\bar{p}$ Collisions at $\sqrt{s}$=1.96 TeV Sarah Schlobohm, Aran Garcia-Bellido We present a search for Higgs bosons produced via the associated $p\bar{p}\to h+b \to\tau+\tau+b$ process at a center-of-mass energy of $\sqrt{s}=$1.96~TeV using up to 4~fb$^{-1}$ of data collected with the D0 detector at the Fermilab Tevatron collider. In supersymmetric models Higgs boson production cross sections can be significantly enhanced compared to the Standard Model; additionally the Higgs boson has a significant branching ratio to tau leptons at all masses. This hybrid ``b-tau'' channel complements the di-tau search channel, in particular providing sensitivity around the $Z$ mass. Particular focus will be given to the case where one of the taus decays hadronically and the other to an electron. [Preview Abstract] |
Tuesday, May 5, 2009 12:21PM - 12:33PM |
W9.00009: Search for Fermiophobic Higgs in $4\gamma$ + X Final State at CDF Atsunari Hamaguchi We present a search for a fermiophobic Higgs boson ($h_{f}$) based on the Type I Two Higgs Doublet Model in which one of the two Higgs doublets has no couplings to fermions. Previous fermiophobic Higgs searches have not been able to exclude a very light $h_{f}$ in the region of large $\tan \beta$ (the ratio between the two vacuum expectation values in the theoretical model). We describe results of searches using the $p\overline{p} \rightarrow H^{\pm} h_{f} \rightarrow W^{*} h_{f} h_{f} \rightarrow 4\gamma + X$ production and decay channel which we expect to be sensitive to this previously unexcluded region. [Preview Abstract] |
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