Bulletin of the American Physical Society
APS April Meeting 2013
Volume 58, Number 4
Saturday–Tuesday, April 13–16, 2013; Denver, Colorado
Session G11: Tevatron, Higgs and top |
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Sponsoring Units: DPF Chair: Nikos Varelas, University of Illinois at Chicago Room: Governor's Square 17 |
Sunday, April 14, 2013 8:30AM - 8:42AM |
G11.00001: The Tevatron's Legacy Thomas Junk The Tevatron, a $p{\bar{p}}$ collider operating initially at a center of mass energy of 1.8 TeV from 1988 to 1996, and at 1.96 TeV from 2001 until 2011, was a groundbreaking, innovative accelerator. It hosted two very productive collider experiments, CDF and D0. Highlights of the physics program are summarized, focusing on those measurements with impacts that last into the LHC era. Experimental techniques and results are summarized in the areas of the physics of the top quark, the electroweak gauge bosons, $B$ hadrons, charm hadrons, and QCD interactions. A selection of results from the searches for the Higgs boson and also for new particles and interactions is presented. [Preview Abstract] |
Sunday, April 14, 2013 8:42AM - 8:54AM |
G11.00002: Jet Energy Resolution in Higgs Boson Searches at the D0 Experiment Savanna Shaw Standard model Higgs boson searches at the D0 experiment at the Fermilab Tevatron collider are primarily sensitive to associated production of the Higgs boson with a vector boson where the Higgs boson decays to a pair of $b$-quarks, when the mass of the Higgs boson is $M_H<135$ GeV. The most powerful variable for separating signal from background events in $H \rightarrow b\bar{b}$ searches is the invariant mass of the dijet system. The resolution with which we can reconstruct this mass depends strongly on the energy resolution of our jets. This jet energy resolution depends on the resolution of our calorimeter, as well as properties of the jet such as whether a jet contains a neutrino from the decay of a $b$ quark. We will present the techniques used to improve the jet energy resolution, and show how these improvements affect the sensitivity of the search for the Higgs boson using the D0 detector. [Preview Abstract] |
Sunday, April 14, 2013 8:54AM - 9:06AM |
G11.00003: Selection of Higgs Boson candidates in the WH channel decaying into a lepton, neutrino, and a pair of $b$-quark jets at D0 detector Ryuji Yamada, Michael Cooke, Alexander Abbinante, Anthony Podkowa, Benjamin Rabe A search is described for Standard Model Higgs boson events in the $WH$ associated production channel, with subsequent decay into a lepton, a neutrino, and two $b$ jets, using 9.7~fb$^{-1}$ of data collected with the D0 detector at the Fermilab Tevatron collider. The search yields an estimated 33 candidate events decaying in this channel with exactly two jets. Among them we estimate 7.7 Higgs boson events with two tight $b$-tagged jets and 11.6 events with one tight $b$ tag. After pre-selection of data, we determine the most likely Higgs boson candidate events using the results of a multivariate analysis. We will explain the characteristics of these events, and show event displays of the most likely Higgs boson candidate events. The same technique can be applied to other channels. [Preview Abstract] |
Sunday, April 14, 2013 9:06AM - 9:18AM |
G11.00004: Search for the Higgs boson in final states with tau-jets Ian Howley Using 9.7~fb$^{-1}$ of data collected using the D0 detector at the Fermilab Tevatron collider, we present a search for the standard model Higgs boson in final states of a lepton ($e$ or $\mu$), a hadronically decaying tau lepton and at least two jets. Several Higgs boson production and decay processes contribute in different proportions as a function of Higgs boson mass. Subsamples of enriched $H \rightarrow W^+W^-$ and $H \rightarrow \tau^+\tau^-$ events are created and a new multivariate method is discussed that reduces the variability of boosted decision tree (BDT) trainings across the mass spectrum. The ratio of 95\% C.L. Higgs boson cross section lower limits from the data to that expected in the standard model is obtained for both subsamples separately and combined. This limit is the most stringent measurement involving $H \rightarrow \tau^+\tau^-$ from the Tevatron. [Preview Abstract] |
Sunday, April 14, 2013 9:18AM - 9:30AM |
G11.00005: Probing spin and parity in the $WH \rightarrow \ell \nu b\bar{b}$ channel at DZero Emily Johnson Standard model Higgs boson searches at the Fermilab Tevatron collider are sensitive to both the rate and kinematic characteristics of Higgs boson production. Using existing searches for Higgs bosons produced in association with vector bosons and with the Higgs boson decaying to pairs of bottom quarks (e.g., $WH \rightarrow \ell \nu b\bar{b}$), we probe the spin-parity value of the Higgs boson. By exploiting the differences in observable kinematics, we attempt to discern the difference between the SM Higgs boson ($J^{P}=0^{+}$), a pseudo-scalar ($J^{P}=0^{-}$) and a graviton-like signal ($J^{P}=2^{+}$). Using up to $9.7$~fb$^{-1}$ of integrated luminosity collected by the D0 detector, we extract p-values for the relative likelihood of the $J^{P}=0^{-}$ and $2^{+}$ hypotheses. [Preview Abstract] |
Sunday, April 14, 2013 9:30AM - 9:42AM |
G11.00006: Composite description of standard-model particles Jaime Besprosvany Finding the Higgs boson, a scalar particle of which there are experimental clues, would confirm the mass-generation mechanism in the standard model. The standard model successfully predicts mass values for the W and Z bosons that carry the short-range electroweak interaction. However, the scalar boson and fermion masses are unknowns as their masses arise from independent Lagrangian terms. The similar order of magnitude of the masses of the W, Z, top quark, and the recently measured scalar excitation, suggests connections among them. Here we present a composite model that describes these particles, based on their properties. [Preview Abstract] |
Sunday, April 14, 2013 9:42AM - 9:54AM |
G11.00007: Is Radiative Electroweak Symmetry Breaking Consistent with a 125 GeV Higgs Mass? Zhi-Wei Wang, Tom Steele The mechanism of radiative electroweak symmetry breaking occurs through loop corrections, and unlike conventional symmetry breaking where the Higgs mass is a parameter, the radiatively-generated Higgs mass is dynamically predicted. Pad\'e approximations and an averaging method are developed to extend the Higgs mass predictions in radiative electroweak symmetry breaking from five- to nine-loop order in the scalar sector of the Standard Model, resulting in an upper bound on the Higgs mass of $141\,{\rm GeV}$. The mass predictions are well-described by a geometric series behaviour, converging to an asymptotic Higgs mass of $125\,{\rm GeV}$ consistent with the recent ATLAS/CMS observations. [Preview Abstract] |
Sunday, April 14, 2013 9:54AM - 10:06AM |
G11.00008: How top quark dipole moments affect Higgs decay Lance Labun, Johann Rafelski The dipole moments of the top quark are sensitive to beyond standard model influences and enter directly in top production in lepton and hadron colliders. We show that the top dipole moments also strongly affect the Higgs-2 photon and Higgs-2 gluon effective couplings: The Higgs-2 photon decay rate can be enhanced by up to a factor 2 at leading order if the top magnetic moment is near zero, and the Higgs-2 gluon decay rate is suppressed by $10\%$ with only a $3\%$ change in the top chromomagnetic moment. In the context of the suggested enhancement of Higgs-2 photon decay at the LHC, these results motivate independent measurement of the top quark dipole moments. We suggest a way to look for Higgs-2 gluon decay as a step toward constraining the top chromomagnetic moment. [Preview Abstract] |
Sunday, April 14, 2013 10:06AM - 10:18AM |
G11.00009: FCNC Top Quark Production Via Anomalous Couplings Elwin Martin, Nikolaos Kidonakis We calculate flavor-changing neutral current (FCNC) processes with top-quark production via anomalous couplings at various energies. We update progress on the FCNC processes $p \bar{p} \to tZ$ and $p \bar{p} \to t \gamma$. We go beyond leading order and include soft-gluon corrections through next-to-leading order. [Preview Abstract] |
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