skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Gluon recombination in high parton density QCD: Inclusive pion production

Abstract

We argue that the collinear factorization of the fragmentation functions in high energy hadron and nuclei collisions breaks down at transverse momenta k{sub T} < or approx. Q{sub s}/g due to high parton densities in the colliding hadrons and/or nuclei. We calculate, at next-to-leading order in projectile parton density and to all orders in target parton density, the double-inclusive cross-section for production of a pair of gluons in the scalar J{sup PC}=0{sup ++} channel. Using the low energy theorems of QCD we find the inclusive cross-section for {pi}-meson production.

Authors:
 [1];  [1];  [2]
  1. Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011 (United States)
  2. (United States)
Publication Date:
OSTI Identifier:
21020282
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. D, Particles Fields; Journal Volume: 75; Journal Issue: 7; Other Information: DOI: 10.1103/PhysRevD.75.074022; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; CROSS SECTIONS; DENSITY; FACTORIZATION; GLUONS; LOW-ENERGY THEOREM; PARTICLE PRODUCTION; PIONS; QUANTUM CHROMODYNAMICS; RECOMBINATION; S QUARKS; SCALARS; TRANSVERSE MOMENTUM

Citation Formats

Li Yang, Tuchin, Kirill, and RIKEN BNL Research Center, Upton, New York 11973-5000. Gluon recombination in high parton density QCD: Inclusive pion production. United States: N. p., 2007. Web. doi:10.1103/PHYSREVD.75.074022.
Li Yang, Tuchin, Kirill, & RIKEN BNL Research Center, Upton, New York 11973-5000. Gluon recombination in high parton density QCD: Inclusive pion production. United States. doi:10.1103/PHYSREVD.75.074022.
Li Yang, Tuchin, Kirill, and RIKEN BNL Research Center, Upton, New York 11973-5000. Sun . "Gluon recombination in high parton density QCD: Inclusive pion production". United States. doi:10.1103/PHYSREVD.75.074022.
@article{osti_21020282,
title = {Gluon recombination in high parton density QCD: Inclusive pion production},
author = {Li Yang and Tuchin, Kirill and RIKEN BNL Research Center, Upton, New York 11973-5000},
abstractNote = {We argue that the collinear factorization of the fragmentation functions in high energy hadron and nuclei collisions breaks down at transverse momenta k{sub T} < or approx. Q{sub s}/g due to high parton densities in the colliding hadrons and/or nuclei. We calculate, at next-to-leading order in projectile parton density and to all orders in target parton density, the double-inclusive cross-section for production of a pair of gluons in the scalar J{sup PC}=0{sup ++} channel. Using the low energy theorems of QCD we find the inclusive cross-section for {pi}-meson production.},
doi = {10.1103/PHYSREVD.75.074022},
journal = {Physical Review. D, Particles Fields},
number = 7,
volume = 75,
place = {United States},
year = {Sun Apr 01 00:00:00 EDT 2007},
month = {Sun Apr 01 00:00:00 EDT 2007}
}
  • We argue that the collinear factorization of the fragmentation functions in high energy hadron and nuclei collisions breaks down at transverse momenta k{sub T} {le} Q{sub s}/g due to high parton densities in the colliding hadrons and/or nuclei. We calculate, at next-to-leading order in projectile parton density and to all orders in target parton density, the double-inclusive cross-section for production of a pair of gluons in the scalar J{sup PC} = 0{sup ++} channel. Using the low energy theorems of QCD we find the inclusive cross-section for {pi}-meson production.
  • Cited by 19
  • A new averaging method is used to combine previously published HERA-I data by the H1 and ZEUS Collaborations of neutral and charged current inclusive cross sections for e{sup {+-}}p scattering. The combination procedure takes into account the systematic error correlations in a coherent approach, leading to a significantly reduced overall cross section uncertainty. This precise combined HERA-I data set is then used as the sole input for a next-to-leading order (NLO) QCD parton distribution function (PDF) fit. The consistent treatment of systematic uncertainties in the combined data results in PDFs with greatly reduced experimental uncertainties compared to the separate analysesmore » of the H1 and ZEUS experiments. Model uncertainties, including those arising from parametrisation dependence, are also carefully considered. The resulting HERAPDFs have impressive precision compared to the global fits.« less
  • It is shown that measurement of the azimuthal asymmetry in semi-inclusive J/psi production may be a good test of the QCD parton model. An additional method of testing the gluon distribution functions in the model of photon-gluon fusion is proposed.
  • The process of deep-inelastic neutrino-nucleon scattering followed by the fragmentation of the possibly existing neutral current into pions is discussed. The quark-parton model allows for the consideration of characteristic effects of a general V and A neutral current. Charged-pion average multiplicities in $nu$ and nu-bar scattering on an isovector target are found to be equal to each other and equal to the corresponding charged-current multiplicities. They are expected to be x- and y-independent and may be accurately calculated (within 10%) from recent electroproduction data. The structure parameters of the neutral current are related to neutral- to charged- current ratios ofmore » $pi$/sup plus-or-minus/ charge asymmetries. The importance of the measurements of these asymmetries is emphasized. (AIP)« less