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

Title: Hadrons and direct photon production in pp and pA collisions at the LHC and saturation effects

Abstract

We investigate hadrons and direct photon production in pp and pA collisions at the energies of RHIC and LHC within the color-dipole approach employing various saturation models. We show that greatest sensitivity to saturation effects is reached at very forward rapidities for pp collisions at LHC ({radical}(s)=14 TeV). The ratio of direct-photon to pion {gamma}/{pi}{sup 0} production can be about 20 divide 10 (at {eta}=7 divide 8). Therefore, direct photon production at forward rapidities should provide a rather clean probe. We calculate the rapidity dependence of the invariant cross section and find some peculiar enhancement at forward rapidities which is more pronounced for direct photon production. We show that this peak is further enhanced by saturation effects. We provide predictions for the nuclear modification factor R{sub pA} for pions and direct photon production in pA collisions at LHC energy at midrapidity. We show within various saturation models that the pion Cronin enhancement at RHIC is replaced by a moderate suppression at LHC energy at midrapidity due to gluon shadowing effects. Cronin enhancement of direct photons can survive at LHC energy within models with a larger saturation scale.

Authors:
 [1];  [1]
  1. Institut fuer Theoretische Physik, Universitaet Regensburg, 93040 Regensburg (Germany)
Publication Date:
OSTI Identifier:
21407977
Resource Type:
Journal Article
Journal Name:
Physical Review. D, Particles Fields
Additional Journal Information:
Journal Volume: 81; Journal Issue: 11; Other Information: DOI: 10.1103/PhysRevD.81.114032; (c) 2010 The American Physical Society; Journal ID: ISSN 0556-2821
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; 73 NUCLEAR PHYSICS AND RADIATION PHYSICS; BROOKHAVEN RHIC; CERN LHC; COLLISIONS; COLOR MODEL; CROSS SECTIONS; DIPOLES; FORECASTING; GLUONS; ION-ATOM COLLISIONS; PARTICLE PRODUCTION; PARTICLE RAPIDITY; PHOTONS; PIONS NEUTRAL; PROTON-PROTON INTERACTIONS; SATURATION; SENSITIVITY; TEV RANGE 10-100; ACCELERATORS; ATOM COLLISIONS; BARYON-BARYON INTERACTIONS; BOSONS; COMPOSITE MODELS; CYCLIC ACCELERATORS; ELEMENTARY PARTICLES; ENERGY RANGE; HADRON-HADRON INTERACTIONS; HADRONS; HEAVY ION ACCELERATORS; INTERACTIONS; ION COLLISIONS; MASSLESS PARTICLES; MATHEMATICAL MODELS; MESONS; MULTIPOLES; NUCLEON-NUCLEON INTERACTIONS; PARTICLE INTERACTIONS; PARTICLE MODELS; PARTICLE PROPERTIES; PIONS; PROTON-NUCLEON INTERACTIONS; PSEUDOSCALAR MESONS; QUARK MODEL; STORAGE RINGS; SYNCHROTRONS; TEV RANGE

Citation Formats

Rezaeian, Amir H, Departamento de Fisica y Centro de Estudios Subatomicos, Universidad Tecnica Federico Santa Maria, Casilla 110-V, Valparaiso, and Schaefer, Andreas. Hadrons and direct photon production in pp and pA collisions at the LHC and saturation effects. United States: N. p., 2010. Web. doi:10.1103/PHYSREVD.81.114032.
Rezaeian, Amir H, Departamento de Fisica y Centro de Estudios Subatomicos, Universidad Tecnica Federico Santa Maria, Casilla 110-V, Valparaiso, & Schaefer, Andreas. Hadrons and direct photon production in pp and pA collisions at the LHC and saturation effects. United States. https://doi.org/10.1103/PHYSREVD.81.114032
Rezaeian, Amir H, Departamento de Fisica y Centro de Estudios Subatomicos, Universidad Tecnica Federico Santa Maria, Casilla 110-V, Valparaiso, and Schaefer, Andreas. Tue . "Hadrons and direct photon production in pp and pA collisions at the LHC and saturation effects". United States. https://doi.org/10.1103/PHYSREVD.81.114032.
@article{osti_21407977,
title = {Hadrons and direct photon production in pp and pA collisions at the LHC and saturation effects},
author = {Rezaeian, Amir H and Departamento de Fisica y Centro de Estudios Subatomicos, Universidad Tecnica Federico Santa Maria, Casilla 110-V, Valparaiso and Schaefer, Andreas},
abstractNote = {We investigate hadrons and direct photon production in pp and pA collisions at the energies of RHIC and LHC within the color-dipole approach employing various saturation models. We show that greatest sensitivity to saturation effects is reached at very forward rapidities for pp collisions at LHC ({radical}(s)=14 TeV). The ratio of direct-photon to pion {gamma}/{pi}{sup 0} production can be about 20 divide 10 (at {eta}=7 divide 8). Therefore, direct photon production at forward rapidities should provide a rather clean probe. We calculate the rapidity dependence of the invariant cross section and find some peculiar enhancement at forward rapidities which is more pronounced for direct photon production. We show that this peak is further enhanced by saturation effects. We provide predictions for the nuclear modification factor R{sub pA} for pions and direct photon production in pA collisions at LHC energy at midrapidity. We show within various saturation models that the pion Cronin enhancement at RHIC is replaced by a moderate suppression at LHC energy at midrapidity due to gluon shadowing effects. Cronin enhancement of direct photons can survive at LHC energy within models with a larger saturation scale.},
doi = {10.1103/PHYSREVD.81.114032},
url = {https://www.osti.gov/biblio/21407977}, journal = {Physical Review. D, Particles Fields},
issn = {0556-2821},
number = 11,
volume = 81,
place = {United States},
year = {2010},
month = {6}
}