Torqued fireballs in relativistic heavy-ion collisions

Journal Article · Tue Mar 15 00:00:00 EDT 2011 · Physical Review. C, Nuclear Physics

DOI:https://doi.org/10.1103/PHYSREVC.83.034911· OSTI ID:21499522

Bozek, Piotr ^[1]; Broniowski, Wojciech ^[1]; Moreira, Joao ^[2]

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1. H. Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, PL-31342 Krakow (Poland)
2. Centro de Fisica Computacional, Department of Physics, University of Coimbra, P-3004-516 Coimbra (Portugal)

We show that the fluctuations in the wounded-nucleon model of the initial stage of relativistic heavy-ion collisions, together with the natural assumption that the forward- (backward-) moving wounded nucleons emit particles preferably in the forward (backward) direction, lead to an event-by-event torqued fireball. The principal axes associated with the transverse shape are rotated in the forward region in the opposite direction than in the backward region. On the average, the standard deviation of the relative torque angle between the forward and backward rapidity regions is {approx}20 deg. for the central and 10 deg. for the midperipheral collisions. The hydrodynamic expansion of a torqued fireball leads to a torqued collective flow, yielding, in turn, torqued principal axes of the transverse-momentum distributions at different rapidities. We propose experimental measures, based on cumulants involving particles in different rapidity regions, which should allow for a quantitative determination of the effect from the data. To estimate the nonflow contributions from resonance decays we run Monte Carlo simulations with therminator, a thermal heavy-ion generator. If the event-by-event torque effect is found in the data, it will support the assumptions concerning the fluctuations in the early stage of the fireball formation, as well as the hypothesis of the asymmetric rapidity shape of the emission functions of the moving sources in the nucleus-nucleus collisions.

• OSTI ID: 21499522
• Journal Information: Physical Review. C, Nuclear Physics, Vol. 83, Issue 3; Other Information: DOI: 10.1103/PhysRevC.83.034911; (c) 2011 American Institute of Physics; ISSN 0556-2813
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ASYMMETRY
COLLISIONS
COMPUTERIZED SIMULATION
DISTRIBUTION
EMISSION
EXPANSION
FLUCTUATIONS
HEAVY ION REACTIONS
HEAVY IONS
HYDRODYNAMIC MODEL
MONTE CARLO METHOD
NUCLEAR FIREBALL MODEL
NUCLEI
NUCLEON-NUCLEON INTERACTIONS
NUCLEONS
PARTICLE RAPIDITY
RELATIVISTIC RANGE
RESONANCE
TRANSVERSE MOMENTUM
BARYON-BARYON INTERACTIONS
BARYONS
CALCULATION METHODS
CHARGED PARTICLES
ELEMENTARY PARTICLES
ENERGY RANGE
FERMIONS
HADRON-HADRON INTERACTIONS
HADRONS
INTERACTIONS
IONS
LINEAR MOMENTUM
MATHEMATICAL MODELS
NUCLEAR MODELS
NUCLEAR REACTIONS
PARTICLE INTERACTIONS
PARTICLE MODELS
PARTICLE PROPERTIES
SIMULATION
STATISTICAL MODELS
THERMODYNAMIC MODEL
VARIATIONS