Longitudinal scaling of observables in heavy-ion collision models

Journal Article · Sun May 15 00:00:00 EDT 2011 · Physical Review. C, Nuclear Physics

DOI:https://doi.org/10.1103/PHYSREVC.83.054902· OSTI ID:21502495

Nasim, Md; Mohanty, Bedangadas ^[1]; Jena, Chitrasen ^[2]; Kumar, Lokesh ^[3]; Netrakanti, Pawan Kumar ^[4]

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1. Variable Energy Cyclotron Centre, Kolkata 700064 (India)
2. Institute of Physics, Bhubaneswar 751001 (India)
3. Kent State University, Kent, Ohio 44242 (United States)
4. Bhabha Atomic Research Centre, Mumbai 400 085 (India)

Longitudinal scaling of pseudorapidity distribution of charged particles (dN{sub ch}/d{eta}) is observed when presented as a function of pseudorapidity ({eta}) shifted by the beam rapidity ({eta}-y{sub beam}) for a wide range of collision systems (e{sup +}+e{sup -}, p+p, d+A, and A+A) and beam energies. Such a scaling is also observed for the elliptic flow (v{sub 2}) of charged hadrons in A+A collisions. This is a striking observation, as v{sub 2} is expected to be sensitive to the initial conditions, the expansion dynamics, and the degrees of freedom of the system, all of which potentially varies with collision system and colliding energies. We present a study of the longitudinal scalings of dN{sub ch}/d{eta}, average transverse momentum (<p{sub T}>), and v{sub 2} using transport models UrQMD and AMPT for Au + Au collisions at center of mass energies ({radical}(s{sub NN})) of 19.6, 62.4, and 200 GeV and Pb + Pb collisions at 2760 GeV. Only the AMPT models which includes partonic effects and quark coalescence as a mechanism of hadronization shows longitudinal scaling for dN{sub ch}/d{eta}, <p{sub T}>, and v{sub 2}. Whereas the UrQMD and AMPT default versions show longitudinal scaling only for dN{sub ch}/d{eta} and <p{sub T}>. We also discuss the possibility of longitudinal scaling of v{sub 2} within two extreme scenarios of models with hydrodynamic and collisionless limits. We find the longitudinal scaling of bulk observables to be an important test for the underlying physics mechanism in models of particle production.

• OSTI ID: 21502495
• Journal Information: Physical Review. C, Nuclear Physics, Vol. 83, Issue 5; Other Information: DOI: 10.1103/PhysRevC.83.054902; (c) 2011 American Institute of Physics; ISSN 0556-2813
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ATOM-ATOM COLLISIONS
BEAMS
CENTER-OF-MASS SYSTEM
CHARGED PARTICLES
COALESCENCE
DEGREES OF FREEDOM
DISTRIBUTION
ELECTRON-POSITRON COLLISIONS
EXPANSION
GEV RANGE
GOLD
HEAVY ION REACTIONS
LEAD
PARTICLE PRODUCTION
PARTICLE RAPIDITY
PROTON-PROTON INTERACTIONS
QUARKS
TEV RANGE 01-10
TRANSPORT THEORY
TRANSVERSE MOMENTUM
ATOM COLLISIONS
BARYON-BARYON INTERACTIONS
COLLISIONS
ELECTRON COLLISIONS
ELEMENTS
ENERGY RANGE
FERMIONS
HADRON-HADRON INTERACTIONS
INTERACTIONS
LINEAR MOMENTUM
METALS
NUCLEAR REACTIONS
NUCLEON-NUCLEON INTERACTIONS
PARTICLE INTERACTIONS
PARTICLE PROPERTIES
POSITRON COLLISIONS
PROTON-NUCLEON INTERACTIONS
TEV RANGE
TRANSITION ELEMENTS