Bulletin of the American Physical Society
2007 APS April Meeting
Volume 52, Number 3
Saturday–Tuesday, April 14–17, 2007; Jacksonville, Florida
Session Y14: QCD Jets |
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Sponsoring Units: DPF Chair: Rob Roser, Fermi National Accelerator Laboratory Room: Hyatt Regency Jacksonville Riverfront City Terrace 10 |
Tuesday, April 17, 2007 1:30PM - 1:42PM |
Y14.00001: D0 Jet Measurements Duncan Brown Jet production mechanisms are studied in proton-antiproton collisions at center-of-mass energies of $\sqrt{s}$ = 1.96 TeV. The data analyzed were collected by the D{\O} Experiment at the TeVatron and correspond to an integrated luminosity of about 1 fb$^{-1}$. Jets are selected using an iterative cone algorithm with $R_{cone}=0.7$ and the results are compared to theoretical models within the framework of perturbative QCD. [Preview Abstract] |
Tuesday, April 17, 2007 1:42PM - 1:54PM |
Y14.00002: Parton level calculations vs. detector level jets: incorporating STAR inclusive jet $A_{LL}$ measurements into global parton analyses Michael Miller Measurements from RHIC of longitudinal spin asymmetries $A_{LL}$ are now available in various reaction channels with increasing statistical precision and are beginning to constrain the integral of the gluon helicity distribution $\Delta $G. In order to extract the maximal information from these measurements, they must ultimately be incorporated into global parton analyses in which theoretical calculations under various assumptions are compared to the world's data from both fixed target deep inelastic scattering and polarized p+p collisions. Using the STAR inclusive jet $A_{LL}$ and cross section measurements as an example, we study how both measurement bias (finite efficiency and transverse momentum resolution) and non-perturbative processes (underlying event and hadronization) affect the comparison of data and theory. While these phenomena may not represent the largest source of uncertainty in global analyses, e.g. compared to uncertainties in functional form of $\Delta $G(x), it is imperative they be quantified. We study the reduced $\chi ^{2}$ distributions when these effects are (i) neglected, (ii) incorporated as systematic uncertainties on the measurement and (iii) used to modify the theoretical prediction via an analytic folding procedure. The latter provides a natural mechanism to account for these effects via a straightforward subroutine call in a global fit. [Preview Abstract] |
Tuesday, April 17, 2007 1:54PM - 2:06PM |
Y14.00003: Jet Energy Scale Determination at D0 Andres Tanasijczuk Many physics measurements at a hadron collider critically depend on an accurate knowledge of the energy of jets resulting from the fragmentation of quarks and gluons generated in the hard interaction. The precise determination of the jet energy scale is a challenging project, involving corrections for physics, instrumental and jet algorithm-dependent effects. We present the most recent determination of the jet energy scale at the D0 experiment during Run II of the Tevatron proton- antiproton collider. We review the procedure followed, the estimated systematic uncertainties, as well as the validation studies performed. The experience gained by the Tevatron experiments in achieving percent-level determination of the jet energy scale should be of great value for the LHC. [Preview Abstract] |
Tuesday, April 17, 2007 2:06PM - 2:18PM |
Y14.00004: A neural net based algorithm to identify b and c jet with the CDF detector Paolo Mastrandrea A sophisticated vertexing algorithm is used to select all the displaced vertices and charged particles produced in the decays of heavy flavor hadrons present in b and c quark jets. The information on tracks and vertices is then used in a neural net to enhance the b to light-jet and b to c-jet discrimination. An additional neural net uses information from traditional tagging algorithms used in CDF (including soft leptons) to produce a final discriminant variable for b and c jets identification. The procedure to validate the algorithm using CDF data will be discussed in this talk. [Preview Abstract] |
Tuesday, April 17, 2007 2:18PM - 2:30PM |
Y14.00005: Jet Fragmentation at CDF Sergo Jindariani Presented are the latest results of jet fragmentation studies at the Tevatron using the CDF Run II detector. Studies include indirectly global event shapes in p-pbar collisions, the distribution of transverse momenta (Kt) of particles in jets, b-jet shapes and two-particle momentum correlations. Results are compared to parton shower Monte Carlos and recent NLLA calculations as well as earlier experimental results from the Tevatron and e+e- colliders. [Preview Abstract] |
Tuesday, April 17, 2007 2:30PM - 2:42PM |
Y14.00006: Measurement of the Inclusive Z+jet(s) Production Cross Section at CDF Oriol Salto, Monica D'Onofrio, Mario Martinez We present preliminary results on inclusive Z-boson plus jets production in $\rm p\bar{p}$ collisions at $\rm \sqrt{s}$ = 1.96 TeV. The measurements are based on 1 fb$^{-1}$ of data collected by the CDF experiment in Run II. The analysis is performed in the context of studies on irreducible backgrounds in searches for new physics in final states with jets and missing transverse energy. The measured cross sections are compared to pQCD NLO predictions. [Preview Abstract] |
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