Bulletin of the American Physical Society
2009 APS April Meeting
Volume 54, Number 4
Saturday–Tuesday, May 2–5, 2009; Denver, Colorado
Session C13: W and Z Physics I |
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Sponsoring Units: DPF Chair: Laura Reina, Florida State University Room: Plaza Court 3 |
Saturday, May 2, 2009 1:30PM - 1:42PM |
C13.00001: Search for a scalar or vector particle decaying into $Zg$ in $p\bar{p}$ collisions at $\sqrt{s}$ = 1.96 TeV Russ Averin We present a search for a narrow scalar or vector resonance decaying into $Zg$ with subsequent $Z$ decay into a pair of electrons or muons. The data for this search were collected with the D0 detector at the Fermilab Tevatron ppbar collider at a center of mass energy of 1.96 TeV. Using about 1 fb$^{-1}$ of data, we observe 49 (50) candidate events in the electron (muon) channel, in good agreement with the standard model prediction. From the combination of both channels we derive 95\% C.L. upper limits on the cross section times branching fraction into $Zg$. These limits range from 0.19 (0.20) pb for a scalar (vector) resonance mass of 600 GeV/c$^2$ to 2.5 (3.1) pb for a mass or 140 GeV/c$^2$. [Preview Abstract] |
Saturday, May 2, 2009 1:42PM - 1:54PM |
C13.00002: Measurement of the ZZ/WZ/WW Diboson cross section in MET+jets final states at CDF Gene Flanagan, Vadim Rusu, Sasha Pronko We present the first measurement of the Di-boson production cross section in the MET+2jet channel in 2.5 fb$^{-1}$ of integrated luminosity of the Fermilab Tevatron's proton-antiproton collisions taken by the CDF II detector. We select events with two jets with $E_T>25$ GeV and significant missing transverse energy, MET. The measurement in this signature is very challenging due to presence of large QCD multi-jet background with fake MET. We use advance techniques to suppress this background by removing events where MET has low significance compared to signal. The MET significance is calculated on event by event basis and takes into account jet energy resolution. [Preview Abstract] |
Saturday, May 2, 2009 1:54PM - 2:06PM |
C13.00003: A study of $Z\rightarrow b\bar{b}$ at Tevatron Suneel Dutt, Suman Bala, Per Jonsson The energy measurement of b-quark jets suffers from biases due to the peculiarities of hadronization and decay of origionating B-hadron. The impact of these effects can be estimated by reconstructing the mass of $Z\rightarrow b\bar{b}$. From the sample of 2$fb^{-1}$ of Data collected by D0 experiment $p \bar{p}$ collisions at Tevatron, we will show how Z signal can be identified and measured. The measurement of reconstructed mass of Z can be used to determine the jet energy scale factors for b-quark jets which allows a reduction of uncertainity in high $p_{T}$ physics analysis. This analysis can help to explore suitable triggering and other necessary tools for Low mass Higgs discovery at Tevatron. [Preview Abstract] |
Saturday, May 2, 2009 2:06PM - 2:18PM |
C13.00004: Vetoing Two Photon Backgrounds with the BeamCal at the ILC Jack Gill, Uriel Nauenberg, Gleb Oleinik $\widetilde{\tau}_1^+\widetilde{\tau}_1^-$ production is a benchmark reaction for ILC detectors. $\widetilde{\tau}_1^\pm$ decays can result in two lepton final states. The same final state can be produced by Standard Model $\gamma^{*}\gamma^{*}$ processes. This makes vetoing $\gamma^{*}\gamma^{*}$ events important for any $\widetilde{\tau}_1^\pm$ reconstruction. Three types of background are considered, and cuts presented which lead to vetoing of these backgrounds. The efficacy of the veto is considered in the light of adding MIP sensitivity to the BeamCal. [Preview Abstract] |
Saturday, May 2, 2009 2:18PM - 2:30PM |
C13.00005: ABSTRACT WITHDRAWN |
Saturday, May 2, 2009 2:30PM - 2:42PM |
C13.00006: Electroweak backgrounds in Di-Photon Analyses at CMS Bernadette Heyburn, Andrew Askew, Yuri Gershtein, Gail Hansen, Robert Stringer, Uriel Nauenberg, Shilei Zang, Daniele Del Re, Shahram Rahatlou, Michael Balazs, Brad Cox New physics could be revealed in a final state with two high $E_T$ photons and large missing transverse energy, for example in Gauge Mediated SUSY breaking theories. Here we present a strategy for coping with the relevant electroweak backgrounds. Electroweak backgrounds are primarily from $W\gamma$ and $Wj$ events where the W decays into an electron and neutrino. If an electron track is not reconstructed, the electron will pass the photon identification. By determining the photon identification efficiency from $Z\rightarrow ee$ events, we can estimate the missing $E_T$ background by scaling electroweak events with respect to the signal. [Preview Abstract] |
Saturday, May 2, 2009 2:42PM - 2:54PM |
C13.00007: Measurement of $W$ boson mass using the ratio method at D0 Feng Guo We measure the ratio of the $W$ and $Z$ boson mass using data collected in the DO Run II at Fermilab Tevatron collider. Our method uses scaled transverse mass spectrum $M_T$ of the $Z$ boson as templates. The $M_W/M_Z$ mass ratio is extracted by fitting to the templates. We will discuss the different corrections needed in this method and compare them with the standard method of $W$ mass measurement. Preliminary results of the measured $W$ boson mass and the uncertainties will be given. [Preview Abstract] |
Saturday, May 2, 2009 2:54PM - 3:06PM |
C13.00008: Search for WW and WZ Production Using the K Nearest Neighbor in Charged Lepton Neutrino Plus Jets Final State at CDF Viviana Cavaliere We present a search for WW and WZ production in lepton-neutrino plus jets final states produced in $p\bar p$ collisions with $\sqrt{s}=1.96$ TeV at Fermilab, Tevatron, using approximately 3 $fb^{-1}$ of data with the CDF II detector. This channel is yet to be observed at hadron colliders. We make use of a new statistical technique (K-nearest neighbour algorithm) to disentangle this process from the large single W plus jets background. This technique takes advantage of the full available information on each event exploiting all the available statistic without rejecting any event. The associated production of a Higgs boson with $W$ boson is topologically similar to our final states and the technique developed in this analysis can also be applied to that search. [Preview Abstract] |
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