Heavy quarkonium production: Nontrivial transition from pA to AA collisions

Journal Article · Sat Jan 15 00:00:00 EST 2011 · Physical Review. C, Nuclear Physics

DOI:https://doi.org/10.1103/PHYSREVC.83.014912· OSTI ID:21499363

Kopeliovich, B Z ^[1]; Potashnikova, I K; Schmidt, Ivan ^[1]; Pirner, H J ^[2]

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1. Departamento de Fisica Universidad Tecnica Federico Santa Maria, Instituto de Estudios Avanzados en Ciencias e Ingenieria, and Centro Cientifico-Tecnologico de Valparaiso, Casilla 110-V, Valparaiso (Chile)
2. Institut fuer Theoretische Physik der Universitaet, Philosophenweg 19, D-69120 Heidelberg (Germany)

Two novel QCD effects, double-color filtering and mutual boosting of the saturation scales in colliding nuclei, affect the transparency of the nuclei for quark dipoles in comparison with proton-nucleus collisions. The former effect increases the survival probability of the dipoles, since color filtering in one nucleus makes the other one more transparent. The second effect acts in the opposite direction and is stronger; it makes the colliding nuclei more opaque than in the case of pA collisions. As a result of parton saturation in nuclei the effective scale is shifted upward, which leads to an increase of the gluon density at small x. This in turn leads to a stronger transverse momentum broadening in AA compared with pA collisions, i.e., to an additional growth of the saturation momentum. Such a mutual boosting leads to a system of reciprocity equations, which result in a saturation scale, a few times higher in AA than in pA collisions at the energies of the large hadron collider (LHC). Since the dipole cross section is proportional to the saturation momentum squared, the nuclei become much more opaque for dipoles in AA than in pA collisions. For the same reason gluon shadowing turns out to be boosted to a larger magnitude compared with the product of the gluon shadowing factors in each of the colliding nuclei. All these effects make it more difficult to establish a baseline for anomalous J/{Psi} suppression in heavy ion collisions at high energies.

• OSTI ID: 21499363
• Journal Information: Physical Review. C, Nuclear Physics, Vol. 83, Issue 1; Other Information: DOI: 10.1103/PhysRevC.83.014912; (c) 2011 American Institute of Physics; ISSN 0556-2813
• Country of Publication: United States
• Language: English

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73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ATOM-ATOM COLLISIONS
CERN LHC
COLLISIONS
COLOR MODEL
COMPARATIVE EVALUATIONS
CROSS SECTIONS
DENSITY
DIPOLES
GLUONS
HEAVY ION REACTIONS
ION-ATOM COLLISIONS
J PSI-3097 MESONS
NUCLEI
OPACITY
PROTON-NUCLEON INTERACTIONS
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QUANTUM CHROMODYNAMICS
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TRANSVERSE MOMENTUM
ACCELERATORS
ATOM COLLISIONS
BARYON-BARYON INTERACTIONS
BARYONS
BOSONS
CHARMONIUM
COMPOSITE MODELS
CYCLIC ACCELERATORS
ELEMENTARY PARTICLES
EVALUATION
FERMIONS
FIELD THEORIES
HADRON-HADRON INTERACTIONS
HADRONS
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ION COLLISIONS
LINEAR MOMENTUM
MATHEMATICAL MODELS
MESONS
MULTIPOLES
NUCLEAR REACTIONS
NUCLEON-NUCLEON INTERACTIONS
NUCLEONS
OPTICAL PROPERTIES
PARTICLE INTERACTIONS
PARTICLE MODELS
PHYSICAL PROPERTIES
QUANTUM FIELD THEORY
QUARK MODEL
QUARKONIUM
STORAGE RINGS
SYNCHROTRONS
VECTOR MESONS