Bulletin of the American Physical Society
2006 APS April Meeting
Saturday–Tuesday, April 22–25, 2006; Dallas, TX
Session E13: Jet and Fragmentation Studies |
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Sponsoring Units: DPF Chair: Andreas Kronfeld, Fermilab Room: Hyatt Regency Dallas Cumberland G |
Saturday, April 22, 2006 3:30PM - 3:42PM |
E13.00001: Inclusive Jet Production using the Midpoint Algorithm in Run II at CDF Craig Group We present a preliminary measurement of the inclusive jet cross section for jets with transverse momenta above 60 GeV/c and with rapidity up to $|Y|$=2.1. The analysis is performed with approximately 800 pb$^{-1}$ of data taken in proton-antiproton collisions at $\sqrt{s}$=1.96 TeV using the upgraded Collider Detector at Fermilab in Run II. This luminosity is more than twice that of our previous measurement. In addition, the rapidity range has been expanded to include the forward region. The results are compared with next to leading order perturbative QCD predictions based on the CTEQ6.1 parton distribution functions. [Preview Abstract] |
Saturday, April 22, 2006 3:42PM - 3:54PM |
E13.00002: Study of $q\bar q \gamma$ and $gg\gamma$ Fragmentation Using Hadron Production In Radiative $\Upsilon$ Decays Hannah Swift Using data collected by the CLEO III detector at the Cornell Electron Storage Ring, we compare hadron production on the $\Upsilon$ resonances to that of the underlying continuum for the $\Lambda$, $p$, $\bar p$, $\phi$ and $f_2$. By examining radiative $\Upsilon$ decays versus photon tagged quark-antiquark events, we have a direct comparison of gluon versus quark fragmentation, allowing us to probe the differing manner in which gluons and quarks hadronize. [Preview Abstract] |
Saturday, April 22, 2006 3:54PM - 4:06PM |
E13.00003: Two-particle momentum correlations in jets at the Tevatron Sergo Jindariani, Andrey Korytov, Alexandre Pronko Presented are the measurements of two-particle momentum correlations in jets produced in p-pbar collisions at center of mass frame energy 1.96 TeV. Studies were performed for charged particles within a restricted opening angle of 0.5 rad around the jet axis and for dijet events with masses ranging from about 60 to 600 GeV. Comparison of the experimental results to the theoretical predictions obtained for partons within the framework of the resummed perturbative QCD (Next-to-leading Log Approximation) shows that the parton momentum correlations do survive the hadronization stage of jet fragmentation, thus giving further support to the hypothesis of Local Parton-Hadron Duality. [Preview Abstract] |
Saturday, April 22, 2006 4:06PM - 4:18PM |
E13.00004: Study of Cell Energy Thresholds in CMS Calorimeters for Jet Reconstruction James Dolen, R. Demina, C. Justus, P. Tipton, M. Zielinski, A. Bhatti Noise in the calorimeter of the Compact Muon Solenoid (CMS) can have a significant impact on the reconstruction of low P$_{T}$ jets. Since noise is associated with individual readouts of calorimeter channels, and the average noise levels vary significantly for different compartments, it is natural to suppress energies of individual hits when building towers for reconstruction of jets and MET. We have proposed new thresholds for calorimeter hits, which are effective in reducing noise contributions to jets, while removing less real jet energy than the often-used cuts on whole towers. The effect of these new thresholds on efficiency, resolution, and fake rate will be presented. [Preview Abstract] |
Saturday, April 22, 2006 4:18PM - 4:30PM |
E13.00005: Study on the Effects of Layered Threshold Cuts on Noise in the CMS Calorimeter Dylan Predergast, R. Demina, J. Dolen, R. Harris, P. Tipton, M. Zielinski Low P$_{T}$ jets are important for understanding new physics at the LHC. In this low P$_{T}$ region, noise can play a substantial role. In order to optimize the energy cuts that best reduce this noise, a quantization of how much noise is in each section of the calorimeter was required. We were then able to compare different energy cuts on different sections of the calorimeter to see where harder or softer cuts needed to be placed. This study used single muon samples to simulate ``noise-only'' events. We found $\sim $8.5 GeV of noise in the calorimeter. We decided on a layered jet energy cut scheme that reduced this noise to $\sim $1.4 GeV. [Preview Abstract] |
Saturday, April 22, 2006 4:30PM - 4:42PM |
E13.00006: Forward Proton Detection at D\O Murilo Rangel Quantum Chromo-Dynamics (QCD) has been a very successful model describing the strong interaction, but its success has been limited primarily to the perturbative regime. About 40\% of the total proton-antiproton cross section at the Tevatron consists of the non-perturbative processes of elastic and diffractive scattering. These processes are better described by the phenomenology of a color singlet exchange of a particle with quantum numbers of the vacuum called the pomeron (Regge theory). The D0 experiment (http://www-d0.fnal.gov) is currently taking data with a forward proton detector (FPD) to better study this process. The FPD data is being used to study the diffractive phenomenology, which has attracted both experimental and theoretical attention. This data provides a unique opportunity to study many topics in the diffractive regime, for instance events which contain a double pomeron exchange. This talk will present FPD data acquired during the last year, focusing on the methods for eliminating background and noise and emphasizing the detector capabilities to explore this interesting physics regime. [Preview Abstract] |
Saturday, April 22, 2006 4:42PM - 4:54PM |
E13.00007: Calibrating the CMS Electromagnetic Calorimeter using $\pi^0$'s Jingzhi Zhang, D. Gong, Y. Kubota, R. Rusack, Y. Gerstein Calibration defines the ultimate performance of the CMS electromagnetic calorimeter (ECAL) at the LHC. The individual calibration of all 75848 crystal channels to the desired precision of 0.5\% is a challenge. $\pi^0\to \gamma\gamma$ has a very large production rate and a substantial sample can be accumulated relatively easily. Here we present a study on calibrating this detector in-situ using inclusive $\pi^0$'s. [Preview Abstract] |
Saturday, April 22, 2006 4:54PM - 5:06PM |
E13.00008: QEDXQCD Exponentiation and Shower/ME Matching at High Energies B.F.L. Ward, Scott A. Yost We present the theory of QEDXQCD exponentiation and how permits the proper shower/ME matching in precision LHC physics scenarios. Applications to single heavy gauge boson production at hadron colliders are illustrated. [Preview Abstract] |
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