Bulletin of the American Physical Society
Inaugural Fall 2009 Meeting of the Prairie Section of the APS
Volume 54, Number 17
Thursday–Saturday, November 12–14, 2009; Iowa City, Iowa
Session G1: Particle Physics II |
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Chair: Robert Zwaska, Fermi National Accelerator Laboratory Room: IMU 335 (Iowa Room) |
Friday, November 13, 2009 2:00PM - 2:12PM |
G1.00001: $J/\psi$ Production Mechanism Measurements at PHENIX Todd Kempel Since the discovery of the $J/\psi$ meson in 1974, several attempts have been made to model the mechanism for its production. No model has yet been able to describe all available data, but experimental progress can be made by making cross section measurements at different energies and polarization measurements for all accessible $J/\psi$ transverse momenta. The capability of the RHIC accelerator to operate at high luminosities for center of mass energies of both 200 and 500 GeV gives an exciting opportunity for the PHENIX experiment to make a significant contribution to the search for a $J/\psi$ production mechanism. In addition to cross section and polarization measurements, $J/\psi$ production from transversely polarized $p+p$ collisions also provides the potential for a new probe of the production mechanism. [Preview Abstract] |
Friday, November 13, 2009 2:12PM - 2:24PM |
G1.00002: CMS HF PMT Abnormal Event Simulation Anthony Moeller Test beam results from 2004 showed that both muons and pions could penetrate through the entire Hadronic Forward (HF) calorimeter of the Compact Muon Solenoid (CMS), striking the PMT windows directly. The particles traveling through the window create Cherenkov radiation, depositing an abnormally large amount of energy compared to the energy collected from the HF. A detector simulation of HF created with Geant4 and CMS Software (CMSSW) was used to investigate this effect. Results for the particles used in test beam (electrons, muons and pions) are included. Also included are results from simple Pythia generated jets. Rates of abnormal events, timing information, as well as results from a few simple abnormal event rejection algorithms are presented. [Preview Abstract] |
Friday, November 13, 2009 2:24PM - 2:36PM |
G1.00003: Finite Size Scaling and Universality in SU(2) Lattice Gauge Theory at Finite Temperature Yuzhi Liu, Alan DenBleyker, Yannick Meurice, Alexander Velytsky We study the 4-th Binder cumulant on $N_\tau \times{N_\sigma}^3$ lattices for a pure SU(2) gauge theory. We use a finer $\beta$ resolution than previous studies in intervals shrinking with the volume in order to reduce the nonlinear effects. We compare different error analysis procedure for the Binder cumulant. We discuss the significance of the small discrepancies between our estimates of the critical exponents and the known values for the 3D Ising model. [Preview Abstract] |
Friday, November 13, 2009 2:36PM - 2:48PM |
G1.00004: Measurement of W Boson Helicity at ATLAS Suyog Shrestha The Standard Model predicts that the top quark almost always decays via the V-A charged current interaction to a W boson and a b quark. It also predicts the fractions of W bosons produced in each polarization state. A measurement of W boson helicity fractions significantly different from the SM values would be an indication of new physics. In this talk I will present results from a Monte Carlo study with an integrated luminosity of 730 pb-1 for the measurement of W boson helicity at ATLAS. [Preview Abstract] |
Friday, November 13, 2009 2:48PM - 3:00PM |
G1.00005: Volume Effect of Fisher zeros in the Nonlinear sigma model Haiyuan Zou, Yannick Meurice In lattice gauge theory, finite size scaling is an important tool to understand finite volume effects and to discriminate among different types of phase transitions. We discuss related issues for 2-dimensional O(N) sigma models in the large-N limit. These models have features similar to 4-dimensional SU(2) and SU(3) gauge theories (asymptotic freedom, mass gap, absence of phase transition at real coupling). We discuss the gap equation at finite volume for complex values of the't Hooft coupling. We show that the singular points of this equation correspond to the end of lines of complex zeros of the partition function. We discuss the scaling of the density of zeros with N and the volume. We briefly discuss the implications of these results for gauge theories. [Preview Abstract] |
Friday, November 13, 2009 3:00PM - 3:12PM |
G1.00006: What Happened to the Spin Crisis in High Energy Physics? Gordon Ramsey Twenty years ago the European Muon Collaboration (EMC) surprised the high-energy world with data that implied the spin of the proton is mostly carried by gluons and not the valence quarks. This resulted in a spate of activity to explain the apparent disagreement of theory and experiment. This paper reviews the theoretical and experimental developments since then to shed light on the spin structure of the proton and neutron. Future plans for extending this to heavier baryons will be discussed. [Preview Abstract] |
Friday, November 13, 2009 3:12PM - 3:24PM |
G1.00007: Study of CMS HF Candidate PMTs With Muons And Cerenkov Light in Electron Showers James Wetzel The response of four different types of PMTs to muons traversing the PMT window at different orientations is measured at CERN H2 test beam. These candidate PMTs for CMS HF upgrade show significantly lower response to PMT window incident muons compared to the currently installed HFPMT due to their thinner windows. For the four anode PMT, a simple and powerful algorithm to identify such events and recover the signal using the remaining quadrants is also presented. For the measurement of PMT responses to Cerenkov light, the HF calorimeter signal was mimicked by two different setups in electron beams and the candidate PMT performances were compared with each other and with HFPMT. Superior performance of particular candidate PMTs was observed against HFPMT. [Preview Abstract] |
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