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

Journal Article · Tue Jun 01 00:00:00 EDT 2010 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.81.114032· OSTI ID:21407977

Rezaeian, Amir H ^[1]; Schaefer, Andreas ^[1]

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1. Institut fuer Theoretische Physik, Universitaet Regensburg, 93040 Regensburg (Germany)

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.

• OSTI ID: 21407977
• Journal Information: Physical Review. D, Particles Fields, Vol. 81, Issue 11; Other Information: DOI: 10.1103/PhysRevD.81.114032; (c) 2010 The American Physical Society; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

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