Bulletin of the American Physical Society
APS April Meeting 2011
Volume 56, Number 4
Saturday–Tuesday, April 30–May 3 2011; Anaheim, California
Session C8: Electroweak and Gauge Boson Physics |
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Sponsoring Units: DPF Chair: Chris Quigg, Fermi National Accelerator Laboratory Room: Grand F |
Saturday, April 30, 2011 1:30PM - 1:42PM |
C8.00001: Measurement of Z$\rightarrow$ee differential cross sections in proton-proton collisions at sqrt(s)=7 TeV with the ATLAS detector Hao Liu We report the differential cross-section measurements of the Z$\rightarrow$ee with respect to the transverse momentum and rapidity of Z boson produced in proton-proton collisions at $\sqrt{s}=7$ TeV with the ATLAS detector. The analysis is based on a dataset corresponding to an integrated luminosity of approximately 36.6 pb$^{-1}$ collected in year 2010. The results are compared with theoretical expectations. [Preview Abstract] |
Saturday, April 30, 2011 1:42PM - 1:54PM |
C8.00002: ABSTRACT WITHDRAWN |
Saturday, April 30, 2011 1:54PM - 2:06PM |
C8.00003: Drell-Yan cross section measurement in the muon channel at the LHC Alexey Svyatkovskiy The first measurement of the Drell-Yan differential cross-section in the muon channel at $\sqrt{s} = 7$ TeV is presented. A data set of 36~pb$^{-1}$ of $pp$ collisions collected by the CMS detector at the LHC during the year 2010 was used for this measurement. Dedicated data-driven methods to estimate the trigger, reconstruction and identification efficiencies and the QCD background were employed. The differential Drell-Yan muon pair production cross-section was measured in the mass range 15--600 GeV and a comparison with theoretical predictions is presented. [Preview Abstract] |
Saturday, April 30, 2011 2:06PM - 2:18PM |
C8.00004: Measurement of the forward-backward charge asymmetry ($A_{\rm FB}$) for $\ell^+\ell^-$ pairs produced via an intermediate $Z/\gamma^*$ at $\sqrt{s} = 7$ TeV in the CMS Youn Roh We present the first measurement of the forward-backward charge asymmetry ($A_{\rm FB}$) for $\ell^+\ell^-$ pairs produced via an intermediate $Z/\gamma^*$ at $\sqrt{s} = 7$ TeV in the CMS experiment in $pp$ collisions. At present, we consider $A_{\rm FB}$ for $e^+e^-$ and $\mu^+\mu^-$ final states separately and compare them with the standard model calculations. Our results are based on an integrated luminosity of $\sim$36 pb$^{-1}$. [Preview Abstract] |
Saturday, April 30, 2011 2:18PM - 2:30PM |
C8.00005: Measurement of the $Z/\gamma^*Z/\gamma^*$ production cross section using the fully charged leptonic decay channel from $p\bar{p}$ collisions at $\sqrt{s} =1.96$ TeV using the D0 detector Ryan Hooper We present a measurement of the $\sigma(Z/\gamma^*Z/\gamma^*)$ production cross section in $p\bar{p}$ collisions at a center-of-mass energy of $\sqrt{s} = 1.96$ TeV, by observing the four charged lepton final state where $Z/\gamma^*Z/\gamma^*\rightarrow\ell^+\ell^-\ell'^+\ell'^-$ ($\ell,\ell'=e$ or $\mu$). This study utilizes $6.4\pm0.3$ fb$^{-1}$ of data collected by the D0 experiment at the Fermilab Tevatron Collider, where we observe ten candidate events with an expected background of $0.35\pm0.04$ events. The p-value of background only fluctuating to the observed number of events or greater is less than $1.3\cdot10^{-9}$ ($> 6\sigma$ gaussian equivalent). The resulting high mass ($M_1(Z/\gamma^*) > 70$ GeV, $M_2(Z/\gamma^*) > 50$ GeV) cross section measurement is $\sigma(p\bar{p}\rightarrow Z/\gamma^*Z/\gamma^*) = 1.35^{+0.50}_{-0.40}(stat)\pm0.15 (syst)$ pb. This result represents the most precise measurement to date for this rare process. We also show various kinematic distributions of our ten candidate events which illustrate that we are at the beginning stages of utilizing $Z/\gamma^*Z/\gamma^*$ phenomena to probe for new physics. [Preview Abstract] |
Saturday, April 30, 2011 2:30PM - 2:42PM |
C8.00006: Angular Coefficients Measurement of Drell-Yan Dielectron Pairs at CDF Jiyeon Han We report on the measurement of the angular distributions of final state electrons in $p\bar{p} \rightarrow \gamma^*/Z \rightarrow e^+e$ events produced in the $Z$ boson region mass range of 66 to 116 GeV/c2 from 2.1 $fb^{-1}$ of proton anti-proton collisions at $\sqrt{s} = 1.96$ TeV taken by the CDF detector at Fermilab. The transverse momentum ($P_T$) dependent angular coefficients A0, A2, A3, and A4 are compared with several predictions based on Quantum Chromodymnamics (QCD). The $P_T$ dependence of A0 and A2 is in agreement with the predictions of perturbative QCD and shows that the production of $Z$ bosons at large $P_T$ proceeds via a combination of the quark-antiquark annihilation and the quark-gluon Compton processes. We find a good agreement with the Lam-Tung relation (A0 = A2), which implies that the spin of the gluon is 1. [Preview Abstract] |
Saturday, April 30, 2011 2:42PM - 2:54PM |
C8.00007: Measurement of $W\rightarrow \ell \nu$ charge asymmetry in proton-proton collisions at $\sqrt{s}=7$~TeV with the ATLAS detector Verena Martinez Outschoorn We present a measurement of the asymmetry in the production rates of positively and negatively charged $W$ bosons in $pp$ collisions at $\sqrt{s}=7$~TeV with the ATLAS detector. The $W$ candidates are reconstructed in the $\ell \nu$ final state, where $\ell=e,\mu$. In a sample corresponding to a total integrated luminosity of $35$ pb$^{-1}$, the differential charge asymmetry as a function of the pseudorapidity $\eta$ of the decay lepton is measured. The lepton charge asymmetry is compared to Standard Model predictions using different parton distribution function predictions. [Preview Abstract] |
Saturday, April 30, 2011 2:54PM - 3:06PM |
C8.00008: Measurement of the W Boson Production Cross-Section in pp Collisions at 7 TeV with the ATLAS Experiment Srivas Prasad We present a measurement of the W boson cross-section in the electron and muon decay channels, using $7\,\mathrm{TeV}$ proton-proton collisions at the LHC. The dataset used in the analysis corresponds to an integrated luminosity of $35\,\mathrm{pb}^{-1}$, collected by the ATLAS detector during 2010. The major backgrounds come from $\mathrm{W}\to\tau\nu$, $\mathrm{Z}\to\mu\mu$ where a lepton is lost, and from QCD, particularly from heavy flavor decays. Lepton kinematic, isolation, missing energy and transverse mass criteria are adopted to extract the signal, and the cross-sections and kinematic distributions are compared with next-to-leading order Standard Model expectations. [Preview Abstract] |
Saturday, April 30, 2011 3:06PM - 3:18PM |
C8.00009: Measurement of $Z+b$ jet production at D0 Ashish Kumar The inclusive $Z+b$ jet production is an important background to searches for the Higgs boson in associated $ZH$ production at the Fermilab Tevatron collider. We present measurements of the ratio of inclusive cross sections for $p\bar{p}\rightarrow Z+b$ jet to $p\bar{p}\rightarrow Z+$ jet production as well as the inclusive $Z+b$ jet cross section. The measurements use a data sample from $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV corresponding to an integrated luminosity of 6.2 fb$^{-1}$ collected by the D0 detector. $Z$ bosons are selected in the electron and muon decay modes. Events containing a $Z$ plus at least one $b$ jet are discriminated from $Z+$charm and light jet(s) events by a novel technique that exploits the properties of the tracks associated to the jet. The measurements are compared with the next-to-leading order theoretical predictions. [Preview Abstract] |
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