Showing papers by "Edmond L. Berger published in 1989"
TL;DR: To help motivate future experiments and assist in their design, predictions of the polarization asymmetry for a range of reasonable choices of the polarized gluon density are provided.
Abstract: Inclusive direct photon production at large transverse momentum in proton-proton interactions with a longitudinally polarized beam and target is an incisive probe of the polarized gluon density in a proton To help motivate future experiments and assist in their design, we provide predictions of the polarization asymmetry for a range of reasonable choices of the polarized gluon density The cross sections are small at fixed-target energies, but the effort to measure them is necessary if the polarized gluon density /Delta//ital G/(/ital x/,/ital Q//sup 2/) is to be determined In order to obtain our predictions, we parametrize spin-dependent parton densities and compute their evolution with /ital Q//sup 2/ Our densities provide good agreement with the spin-dependent structure function /ital g//sub 1//sup /ital p//(x,/ital Q//sup 2/) measured in deep-inelastic lepton scattering
32 citations
TL;DR: A relation between the asymmetry in /ital W//sup /plus minus minus//rapidity distributions and the ratio of deep-inelastic lepton-hadronscattering structure functions is derived and the production rates of weak bosons also becomesensitive to production via the charm quark.
Abstract: Weak bosons are produced in hadron collisions by quarks and antiquarks withaverage fractional momenta /ital x/=/ital M//sub /ital W/,/ital Z/// /radical/s . When /radical//ital s/is increased by a factor of 3, the average value of /ital x/ shifts fromabout 0.15 at CERN /ital pp/bar // collider energies to 0.05 at the FermilabTevatron, i.e., from a regime where valence quarks dominate to a regime wheresea quarks dominate the production features of weak bosons. We investigatesystematically the problem of calculating /ital W/ and /ital Z/ cross sections inthis new regime, paying special attention to the ratio/sigma/(/ital W/)//sigma/(/ital Z/) which is necessary for determining the ratio oftotal widths /Gamma/(/ital W/)//Gamma/(/ital Z/) from hadron-collider data. Weemphasize that with the increased statistics in /ital pp/bar // experiments, theparton fluxes responsible for the production of weak bosons can be controlledinternally by a study of the asymmetry of the rapidity distribution of the/ital W/ boson. We derive a relation between the asymmetry in /ital W//sup /plus minus//rapidity distributions and the ratio/ital F//sub 2//sup /ital n///F/sub 2//sup p/ of deep-inelastic lepton-hadronscattering structure functions. The production rates of weak bosons also becomesensitive to production via the charm quark. This calculation raises someinteresting theoretical issues. We discuss both problems inmore » detail. We alsostudy the implications of our results for the determination of the number oflight neutrinos and the mass of the top quark via a measurement of the/ital W/-to-/ital Z/ event ratio.« less
26 citations
TL;DR: The experiments could take advantage of recent advances in the technology of polarized {sup 6}LiD, and provide important constraints on the polarization asymmetry of the gluon density in a nucleon.
Abstract: Predictions are presented of the polarization asymmetry in prompt photon production at large transverse momentum in the scattering of longitudinally polarized protons from longitudinally polarized deuteron targets. Data would provide important constraints on the polarization asymmetry of the gluon density in a nucleon. The experiments could take advantage of recent advances in the technology of polarized $^{6}\mathrm{Li}$D.
11 citations
7 citations
01 Jan 1989
TL;DR: A review of heavy quark production in p p, π - p, and pp interactions at fixed target and collider energies is presented in this paper, including contributions through next-to-leading order in QCD perturbation theory.
Abstract: A review is presented of heavy quark production in p p, π - p, and pp interactions at fixed target and collider energies. Calculations of total cross sections are described including contributions through next-to-leading order in QCD perturbation theory. Comparisons with available data on charm and bottom quark production show good agreement for reasonable values of charm and bottom quark masses and other parameters. Open issues in the interpretation of results are summarized. A discussion is presented of signatures, backgrounds, and expected event rates for top quark production.