Absorption in Heavy-Ion Collisions (original) (raw)
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Heavy quarkonium dissociation cross sections in relativistic heavy-ion collisions
Physical Review C, 2001
Many of the hadron-hadron cross sections required for the study of the dynamics of matter produced in relativistic heavy-ion collisions can be calculated using the quark-interchange model. Here we evaluate the low-energy dissociation cross sections of J/ψ, ψ ′ , χ, Υ, and Υ ′ in collision with π, ρ, and K, which are important for the interpretation of heavy-quarkonium suppression as a signature for the quark gluon plasma. These comover dissociation processes also contribute to heavy-quarkonium suppression, and must be understood and incorporated in simulations of heavy-ion collisions before QGP formation can be established through this signature.
Collectivity of J/ψ Mesons in Heavy-Ion Collisions
Physical Review Letters
The production of J=ψ mesons in heavy-ion collisions at the Large Hadron Collider is believed to be dominated by the recombination of charm and anticharm quarks in a hot QCD medium. However, measurements of the elliptic flow (v 2) of J=ψ mesons in these reactions are not well described by existing calculations of J=ψ recombination for transverse momenta p T ≳ 4 GeV. We revisit these calculations in two main aspects. Employing the resonance recombination model, we implement distribution functions of charm quarks transported through the quark-gluon plasma using state-of-the-art Langevin simulations and account for the space-momentum correlations of the diffusing charm and anticharm quarks in a hydrodynamically expanding fireball. This extends the relevance of the recombination processes to substantially larger momenta than before. We also revisit the suppression of primordially produced J=ψ's by propagating them through the same hydrodynamic medium, leading to a marked increase of their v 2 over previous estimates. Combining these developments into a calculation of the p T-dependent nuclear modification factor and v 2 of inclusive J=ψ production in semicentral Pb-Pb collisions at the LHC, we find a good description of the experimental results by the ALICE Collaboration. Our results thus resolve the abovementioned v 2 puzzle and imply the relevance of recombination processes for p T 's of up to ∼8 GeV.
Dynamical quark recombination in ultrarelativistic heavy-ion collisions and the proton-to-pion ratio
Physical Review C, 2008
We study quark thermal recombination as a function of energy density during the evolution of a heavy-ion collision in a numerical model that reproduces aspects of QCD phenomenology. We show that starting with a set of free quarks (or quarks and antiquarks) the probability to form colorless clusters of three quarks differs from that to form colorless clusters of quark-antiquark and that the former has a sharp jump at a critical energy density whereas the latter transits smoothly from the low to the high energy density domains. We interpret this as a quantitative difference in the production of baryons and mesons with energy density. We use this approach to compute the proton and pion spectra in a Bjorken scenario that incorporates the evolution of these probabilities with energy density, and therefore with proper time. From the spectra, we compute the proton to pion ratio and compare to data at the highest RHIC energies. We show that for a standard choice of parameters, this ratio reaches one, though the maximum is very sensitive to the initial evolution proper time.
Signatures of absorption mechanisms for and ψ′ production in high-energy heavy-ion collisions
Nuclear Physics A, 1998
Oak Ridge, TN 37831 J/ψ and ψ ′ produced in high-energy heavy-ion collisions are absorbed by their collisions with nucleons and produced soft particles, leading to two distinct absorption mechanisms. The signature of absorption by produced soft particles, as revealed by ψ ′ production data, consists of a gap and a change of the slope in going from the pA line to the nucleus-nucleus line when we make a semi-log plot of the survival probability as a function of the path length. Using this signature, we find from the J/ψ production data in pA, O-Cu, O-U, and S-U collisions that the degree of J/ψ absorption by produced soft particles is small and cannot account for the J/ψ data in Pb-Pb collisions. The anomalous suppression of J/ψ production in Pb-Pb collisions can be explained as due to the occurrence of a new phase of strong J/ψ absorption, which sets in when the local energy density exceeds about 3.4 GeV/fm 3 . To probe the chemical content of the new phase, we propose to study the abundance of open-charm mesons and charm hyperons which depends sensitively on the quark chemical potential.
Collectivity of J/psiJ/\psiJ/psi Mesons in Heavy-Ion Collisions
2021
The production of J/ψ mesons in heavy-ion collisions at the Large Hadron Collider is believed to be dominated by the recombination of charm and anti-charm quarks in a hot QCD medium. However, measurements of the elliptic flow (v2) of J/ψ mesons in these reactions are not well described by existing calculations of J/ψ recombination for transverse momenta pT & 4GeV. Here, we revisit these calculations in two main aspects. By employing the resonance recombination model, we implement distribution functions of charm quarks transported through the quark-gluon plasma using state-of-the-art Langevin simulations, and we account for the space-momentum correlations of the diffusing charm and anti-charm quarks in the hydrodynamically expanding fireball. These improvements extend the relevance of the recombination processes to substantially larger momenta than before. In addition, we revisit the suppression of the primordially produced J/ψ mesons by propagating them through the same hydrodynamic...
Pion multiplicity as a probe of the deconfinement transition in heavy-ion collisions
Physics Letters B, 1992
The hydrochemical model is used to calculate the pion multiplicity in relativistic hea,,3'-ion collisions. Chemical reactions are explicitly taken into account in the expansion stage of the hadronic phase. It leads to the absence of chemical equilibrium among hadronic particles and a nonzero value of the pion chemical potential at thermal freeze out. We find a specific structure in the incident energy, dependence of the pion multiplicity as a result of the formation of the quark-hadron mixed phase in the initial stage of the collision.
Physical Review C, 2002
Many of the hadron-hadron cross sections required for the study of the dynamics of matter produced in relativistic heavy-ion collisions can be calculated using the quark-interchange model. Here we evaluate the low-energy dissociation cross sections of J/ψ, ψ ′ , χ, Υ, and Υ ′ in collision with π, ρ, and K, which are important for the interpretation of heavy-quarkonium suppression as a signature for the quark gluon plasma. These comover dissociation processes also contribute to heavy-quarkonium suppression, and must be understood and incorporated in simulations of heavy-ion collisions before QGP formation can be established through this signature.
International Journal of Modern Physics A, 2016
This is a review of the Quantum Chromodynamics Cosmological Phase Transitions, the quark–gluon plasma, the production of heavy quark states via [Formula: see text]–[Formula: see text] collisions and Relativistic Heavy Ion Collisions (RHIC) using the mixed hybrid theory for the [Formula: see text] and [Formula: see text] states; and the possible detection of the quark–gluon plasma via heavy quark production using RHIC. Recent research on fragmentation for the production of [Formula: see text] mesons is reviewed, as is future theoretical and experimental research on the Collins and Sivers fragmentation functions for pions produced in polarized [Formula: see text]–[Formula: see text] collisions.