Strangeness evolution in the central region of a heavy-ion collision with transverse flow effects

Kajantie, K.; Kataja, M.; Ruuskanen, P.V.

doi:10.1016/0370-2693(86)90453-3

Cited by 29 publications

(3 citation statements)

References 8 publications

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“…One can, namely, immediately guess that the number of thermal photons or thermal dileptons produced for the richer equation of state would be smaller. One may also witness a unique sensitivity on the extent of the strangeness equilibration [10] from such varied flow profiles of the system. These large differences could also be observed from pion interferometry.…”

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confidence: 99%

Equation of state of hadronic matter and electromagnetic radiation from relativistic heavy ion collisions

1998

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We study the radiation of thermal photons and dileptons likely to be produced in relativistic heavy ion collisions. We find that the thermal photon multiplicity scales with the charged pion multiplicity as (dN ch /dy) α with α ∼ 1.2 for a transversely expanding system, contrary to the general belief of a quadratic dependence. The scaling is shown to be valid, both for real and virtual photons. The coefficient of proportionality at a given energy may help us identify the appropriate equation of state of hot hadronic matter produced in such collisions.PACS numbers: 25.75. Dw, 12.38.Mh, 24.10.Nz, 25.75.Gz The search for the quark-gluon plasma (QGP), a deconfined state of strongly interacting matter, is entering a decisive phase. Evidence has been mounting for some time now, that such matter is perhaps being produced in collisions involving heavy nuclei at the CERN Super Proton Synchrotron (SPS). If confirmed, this holds out a promise that the QGP likely to be created at the Brookhaven Relativistic Heavy Ion Collider (RHIC) and the CERN Large Hadron Collider (LHC) will occupy a much larger space-time volume, in similar collisions. The plasma thus produced will have to expand and cool, due to large internal pressure. It has also to undergo hadronization, once the temperature drops below the transition temperature. These hadrons may continue to interact for some time before their density gets too low to support frequent collisions. We may also have a mixed phase of quarks, gluons, and hadrons during which the speed of sound may become vanishingly small, if quantum chromodynamics admits a first order phase transition.Many of the observables from the above collisions, like the particle distributions, electromagnetic radiation, the spatial and temporal dimensions of the fireball etc., will be decided by the equation of state of hadronic matter. The transverse expansion of the system which drastically alters the time scales in the system, at least with regard to the mixed and the hadronic phases is also affected by the equation of state [1]. What should be the equation of state of hot hadronic matter which is created in heavy ion collisions? It is expected that if the tran-sition temperature is very close to the pion mass then the hadronic matter could possibly well be determined by pions and only a few low lying mesonic resonances. The hadronic matter is likely to be populated by heavier hadrons once the temperature is higher. Will these hadrons stay in chemical and thermal equilibrium, till the freeze-out? This will be decided by the competition between the collision frequency and the rate of expansion, and if valid, it will be reflected in uniquely determined particle ratios [2]. It is not difficult to imagine that the equation of state or at least the composition of the hadronic matter may be somehow related to the manner in which the hadronization proceeds. This aspect has not yet received enough attention as it involves the non-perturbative realm of quantum chromodynamics.The question of hadronization of the plasm...

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confidence: 99%

Equation of state of hadronic matter and electromagnetic radiation from relativistic heavy ion collisions

1998

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“…This can be understood by noting that the evolution of the partonic density which is governed by ∂ µ (nu µ ) consists of two terms: u µ ∂ µ n which is the rate of change of the density in the comoving frame, and n ∂ µ u µ which is the rate of change of the density due to the expansion of the fluid element in the comoving frame [8]. Once the transverse expansion of the fluid starts developing, the second term and also the radial derivatives in (4) grow very rapidly and drive the system away from chemical equilibrium.…”

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Chemical equilibration of an expanding quark-gluon plasma

1997

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The chemical equilibration of the parton distribution in collisions of two heavy nuclei at the CERN Large Hadron Collider is investigated. Initial conditions are obtained from a self-screened parton cascade calculation. The onset of transverse expansion of the system is found to impede the chemical equilibration. The system initially approaches chemical equilibrium, but then is driven away from it, when the transverse velocity becomes large. PACS: 25.75.Ld, 12.38.Mh Typeset using REVT E X 1

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“…It should be emphasized that the normalization of kaons and protons relative to pions depends strongly on the decoupling temperature which is here assumed to be the same for all particles, T dec ≃ 120 MeV. It is more likely that the number of kaons [18] and protons freezes out earlier than at the kinetic freeze-out. This would increase their normalization relative to pions but the shape of the spectrum could change less since the elastic collisions could still take place.…”

Section: Results and Comparison With Experimentsmentioning

confidence: 99%

From quark–gluon plasma to hadron spectra

Ruuskanen¹

2002

Nuclear Physics A

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Results on initial transverse energy production based on NLO perturbative QCD calculation with final state saturation of produced minijets are used to fix the initial energy density of produced matter. Assuming rapid thermalization, this provides the initial conditions for a hydrodynamic description of the expansion of final matter. Given a prescription of the the decoupling of particles from the thermal system to free particles, final transverse spectra of hadrons and integrated quantities like multiplicity and transverse energy can be calculated in the central rapidity region. Results are reported and compared with measurements.

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Strangeness evolution in the central region of a heavy-ion collision with transverse flow effects

Cited by 29 publications

References 8 publications

Equation of state of hadronic matter and electromagnetic radiation from relativistic heavy ion collisions

Equation of state of hadronic matter and electromagnetic radiation from relativistic heavy ion collisions

Chemical equilibration of an expanding quark-gluon plasma

From quark–gluon plasma to hadron spectra

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