Bulletin of the American Physical Society
78th Annual Meeting of the Southeastern Section of the APS
Volume 56, Number 9
Wednesday–Saturday, October 19–22, 2011; Roanoke, Virginia
Session NB: Particle Physics II |
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Chair: Craig Group, University of Virginia Room: Crystal Ballroom B |
Saturday, October 22, 2011 8:30AM - 8:42AM |
NB.00001: Search for a Fourth Generation t' Quark via Wb Decays into a Lepton Plus Jets Final State in 7 TeV pp Collisions Charles Jenkins The CMS Experiment at the LHC is currently observing 7 TeV center of mass energy pp collisions. One of the many beyond the standard model searches being conducted by CMS is for evidence of a fourth generation top-like quark (t'). If this object exists, it is expected to decay as: t' $\to $ W b. In pp collisions the top-like quark would be produced with its anti-quark (pp$\to $t't\={ }'$\to $W+bW-b\={ }). This search looks for this decay where one of the W bosons decays leptonically (W$\to $lepton neutrino) and the other hadronically (W$\to $qq\={ }). This analysis studies two channels: muon+jets and electron+jets. Results from a sample of 684 pb-1 muon+jets and 573pb-1 electrons+jets will be presented. [Preview Abstract] |
Saturday, October 22, 2011 8:42AM - 8:54AM |
NB.00002: Techniques for Higgs Hunting at D0 Huong Ngyuen This talk will discuss several techniques employed to increase sensitivities in searches for the standard model Higgs boson at the D0 Experiment, including kinematic fits, matrix element methods, and kinematically motivated divisions of data. Examples from recent data analysis work will be presented. [Preview Abstract] |
Saturday, October 22, 2011 8:54AM - 9:06AM |
NB.00003: Angular Distribution of Z$^{0}$ Bosons in Z$^{0}$+Jet Events Luis Lebolo The Z$^{0}$ boson center-of-mass angular distribution is measured in proton-proton collisions at $\sqrt{s}$ = 7~TeV, at the CERN LHC. The advantage of studying the angular distribution is that the partonic cross section is solely a function of $\hat{s}$ and $cos\hat{\theta}$; it does not depend on the details of the parton distribution functions. The data sample, recorded with the CMS detector, corresponds to an integrated luminosity of approximately 36~pb$^{-1}$. Events in which there is a Z$^{0}$ and at least one jet, with a transverse momentum threshold of 20~GeV and absolute rapidity less than 2.5, are selected for this analysis. Only the Z$^{0}$'s muon decay channel is studied. Within experimental and theoretical uncertainties, the measured angular distribution is in agreement with next-to-leading order perturbative QCD predictions. This analysis extends the phase space available to previous Tevatron studies by probing larger values of $\hat{s}$ and center-of-mass rapidities. [Preview Abstract] |
Saturday, October 22, 2011 9:06AM - 9:18AM |
NB.00004: Identifying Electromagnetic Events in the Forward Hadron Calorimeter Christopher Frye The Forward Hadron Calorimeter (HF) of the Compact Muon Solenoid (CMS) at the Large Hadron Collider (LHC) lies in a region not covered by an inner tracking system, and we can rely only on the shapes of showers that hit the HF to determine whether or not they are due to electromagnetic particles. We review the current method of distinguishing shower types in the HF, and we bring attention to a drawback that will become present as the luminosity of the LHC increases and creates a need for tighter shower-shape cuts. We provide a method to correct this drawback, and we analyze the effectiveness of various tight cuts at isolating signal from background. [Preview Abstract] |
Saturday, October 22, 2011 9:18AM - 9:30AM |
NB.00005: Precision Measurement of anti-B0bar-$>$D*+ Lepton Neutrino Branching Fraction Christopher Buchanan, Shannon Eynon, Rafi Qumsieh, Romulus Godang We present a precision measurement of the exclusive anti-B0 meson decays to D*+, lepton, and anti-neutrino using 476 million B-meson anti-B-meson pairs. The data sample collected with the BABAR detector at the PEP-II asymmetric-energy B-Factory at SLAC National Accelerator Laboratory. The anti-B0 mesons are reconstructed using a partial reconstruction in which the D* four-momentum is inferred from the slow pion. This allows for a much higher statistical precision on this branching fraction. We use a single and double tag method to measure this important branching fraction. [Preview Abstract] |
Saturday, October 22, 2011 9:30AM - 9:42AM |
NB.00006: CP Violation in B Decays at BABAR Romulus Godang We report on the study of the decay B+ to D0(D0bar) K+ where the D0 or D0bar meson decaying to Kpipi and Kpipi0, with the Atwood Dunietz and Soni (ADS) and Gronau, London, and Wyler (GLW) methods. We measure the ratios Rads, R+, and R- since the processes B+ to D0barK+ and B+ to D0K+ are proportional to Vcb and Vub, respectively, are sensitive to rB and to the weak phase angle gamma. [Preview Abstract] |
Saturday, October 22, 2011 9:42AM - 9:54AM |
NB.00007: Measurement of the Branching Fraction of Y(4S) to Neutral B Pairs Rafi Qumsieh, Christopher Buchanan, Shannon Eynon, Romulus Godang We measure a model independent measurement of the branching fraction of Upsilon(4S) to neutral B pairs. We use a sample of 476 million B-meson anti-B-meson pairs collected at the Upsilon(4S) resonance with the BABAR detector at the PEP-II asymmetric-energy B-Factory at SLAC National Accelerator Laboratory. The B mesons are reconstructed through the channel of anti-B0 decays to D*+ lepton anti-neutrino using a partial reconstruction method. Our result does not depend on any branching fraction, the reconstruction efficiency, and the ratio of the charged and neutral B meson. This measurement is an important input for normalizing many B mesons decay. [Preview Abstract] |
Saturday, October 22, 2011 9:54AM - 10:06AM |
NB.00008: Angular Distribution of Photons in $\gamma$+Jet Events Vanessa Gaultney The angular distribution of prompt photons in events with at least one jet in the center-of-mass frame for pp collisions at $\sqrt{s} = $7 TeV is presented. A template method is used to distinguish between signal and the dominant background from jets fragmenting into neutral mesons. Measuring the angular distribution is a direct probe of the partonic cross section for prompt photon production and is free of the parton distribution functions that are normally associated with an inclusive cross section measurment typically used for next-to-leading order predictions. The $|\hat{\eta}|$ distribution in the center-of-mass frame ranging from 0-2.1 ($|cos \hat{\theta}|$ 0-0.97) is examined and compared to next-to-leading order QCD predictions, the highest angular limit reached since the last measurement of angular distributions nearly a decade ago. [Preview Abstract] |
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