Article

Inclusive Measurements of Inelastic Electron and Positron Scattering from Unpolarized Hydrogen and Deuterium Targets

Journal of High Energy Physics (Impact Factor: 6.22). 05/2011; 1105((2011)):1-39. DOI: 10.1007/JHEP05(2011)126

ABSTRACT Results of inclusive measurements of inelastic electron and positron scattering from unpolarized protons and deuterons at the HERMES experiment are presented. The structure functions F
2p
and F
2d
are determined using a parameterization of existing data for the longitudinal-to-transverse virtual-photon absorption cross-section ratio. The HERMES results provide data in the ranges 0.006 ≤ x ≤ 0.9 and 0.1 GeV2 ≤ Q
2 ≤ 20 GeV2, covering the transition region between the perturbative and the non-perturbative regimes of QCD in a so-far largely unexplored kinematic region. They are in agreement with existing world data in the region of overlap. The measured cross sections are used, in combination with data from other experiments, to perform fits to the photon-nucleon cross section using the functional form of the ALLM model. The deuteron-to-proton cross-section ratio is also determined.

Download full-text

Full-text

Available from: Vahagn Gharibyan, Aug 22, 2015
0 Followers
 · 
177 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: Recent QCD results from electron–proton interactions at HERA and JLAB are presented. Inclusive cross-section measurements as well as studies of the hadronic final state like jet production or the production of heavy quarks are discussed. The results are compared with perturbative QCD predictions and their impact on the determination of the parton density functions of the proton as well as of the strong coupling α s is discussed.
    Pramana 10/2012; 79(4). DOI:10.1007/s12043-012-0364-8 · 0.72 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A measurement of the virtual-photon asymmetry A 2(x,Q 2) and of the spin-structure function g 2(x,Q 2) of the proton are presented for the kinematic range 0.004<x<0.9 and 0.18 GeV2<Q 2<20 GeV2. The data were collected by the HERMES experiment at the HERA storage ring at DESY while studying inclusive deep-inelastic scattering of 27.6 GeV longitudinally polarized leptons off a transversely polarized hydrogen gas target. The results are consistent with previous experimental data from CERN and SLAC. For the x-range covered, the measured integral of g 2(x) converges to the null result of the Burkhardt–Cottingham sum rule. The x 2 moment of the twist-3 contribution to g 2(x) is found to be compatible with zero.
    European Physical Journal C 03/2012; 72(3):7. DOI:10.1140/epjc/s10052-012-1921-5 · 5.44 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We outline the many quarkonium-physics opportunities offered by a multi-purpose fixed-target experiment using the p and Pb LHC beams extracted by a bent crystal. This provides an integrated luminosity of 0.5 fb-1 per year on a typical 1cm-long target. Such an extraction mode does not alter the performance of the collider experiments at the LHC. With such a high luminosity, one can analyse quarkonium production in great details in pp, pd and pA collisions at sqrt(sNN)~115 GeV and at sqrt(sNN)~72 GeV in PbA collisions. In a typical pp (pA) run, the obtained quarkonium yields per unit of rapidity are 2-3 orders of magnitude larger than those expected at RHIC and about respectively 10 (70) times larger than for ALICE. In PbA, they are comparable. By instrumenting the target-rapidity region, the large negative-xF domain can be accessed for the first time, greatly extending previous measurements by Hera-B and E866. Such analyses should help resolving the quarkonium-production controversies and clear the way for gluon PDF extraction via quarkonium studies. The nuclear target-species versatility provides a unique opportunity to study nuclear matter and the features of the hot and dense matter formed in PbA collisions. A polarised proton target allows the study of transverse-spin asymmetries in J/psi and Upsilon production, providing access to the gluon and charm Sivers functions.
    Few-Body Systems 04/2012; 53(1). DOI:10.1007/s00601-012-0445-8 · 1.51 Impact Factor
Show more