Charmonium production at heavy-ion colliders is considered within the comovers interaction model. The formalism is extended by including possible secondary J/psi production through recombination and an estimate of recombination effects is made with no free parameters involved. The comovers interaction model also includes a comprehensive treatment of initial-state nuclear effects, which are discussed in the context of such high energies. With these tools, the model properly describes the centrality and the rapidity dependence of experimental data at RHIC energy, $\sqrt{s}$ = 200 GeV, for both Au+Au and Cu+Cu collisions. Predictions for LHC, $\sqrt{s}$ = 5.5 TeV, are presented and the assumptions and extrapolations involved are discussed.
K*-charmonium dissociation reactions in hadronic matter are studied in the Born approximation, in the quark-interchange mechanism, and with a temperature-dependent quark potential. We obtain the temperature dependence of unpolarized cross sections for K*-charmonium dissociation reactions which produce charmed mesons and charmed strange mesons. We use the cross sections for charmonium dissociation in collisions with pion, rho meson, kaon, vector kaon, and eta meson to calculate dissociation rates of charmonium with the five types of mesons. Because of the temperature dependence of the meson mas…
We study kaon-charmonium and eta-charmonium dissociation reactions. The K-charmonium dissociation and the eta-charmonium dissociation include 27 reactions. Cross sections for the reactions are calculated in the Born approximation, in the quark-interchange mechanism and with a temperature-dependent quark potential. The temperature dependence of peak cross sections of endothermic reactions is linked to the temperature dependence of quark-antiquark relative-motion wave functions, meson masses and the quark potential. Although the eta meson and kaon have similar masses, the energy and temperature …
Meson-charmonium dissociation reactions governed by the quark interchange are studied with temperature-dependent quark potentials. Quark-antiquark relative-motion wave functions and masses of charmonia and charmed mesons are determined by the central spin-independent part of the potentials or by the central spin-independent part and a smeared spin-spin interaction. The prominent temperature dependence of the masses is found. Based on the potentials, the wave functions, and the meson masses, we obtain temperature-dependent cross sections for fifteen pion-charmonium and rho-charmonium dissociati…
We study electromagnetic field effect on charmonium gluon-dissociation in quark-gluon plasma. With the effective Hamiltonian derived from QCD multipole expansion under an external electromagnetic field, we first solve the two-body Schrödinger equation for a pair of charm quarks with mean field potentials for color and electromagnetic interactions and obtain the charmonium binding energies and wave functions, and then calculate the gluon-dissociation cross-section and decay width by taking the color electric and magnetic dipole interactions as perturbations above the mean field and employing Fe…
Physics of charmonium suppression in nuclear collisions drastically changes between the energies of SPS and RHIC. Mechanisms suppressing charmonia at SPS are reviewed, neither of which is important at RHIC. On the other hand, coherence, or shadowing of c-quarks and gluons barely seen at SPS, become a dominant effect at RHIC providing a much stronger suppression. A onset of coherence at Fermilab energies explains the observed cross section ratio steeply falling at large Feynman x_F. In nuclear collisions variation of charmonium suppression with x_F suggests a sensitive probe for QGP.
Charmonium dissociation cross sections due to flavor-exchange charmonium-baryon scattering are computed in the constituent quark model. We present results for inelastic $J/ψN$ and $η_c N$ scattering amplitudes and cross sections into 46 final channels, including final states composed of various combinations of $D$, $D^*$, $Σ_c$, and $Λ_c$. These results are relevant to experimental searches for the deconfined phase of quark matter, and may be useful in identifying the contribution of initial $c\bar c$ production to the open-charm final states observed at RHIC through the characteristic flavor …
By solving the covariant relativistic Schrödinger equations for a pair of heavy quarks, we obtained the wave functions for the ground and excited quarkonium states at finite temperature. In comparison with the non-relativistic calculation, the $J/ψ$ dissociation temperature determined by the infinity size or zero binding energy of the system increases $7%-13%$, when the central potential varies between the free energy and internal energy.
Production of J/$ψ$ from nucleus-nucleus reactions depends sensitively on the dissociation cross section with light hadrons. Effective lagrangian methods are used to describe the hadronic degrees of freedom, including strangeness and charm. Cross sections with pions, rho mesons, kaons and nucleons having magnitudes 4--8 mb are found, and with steep thresholds. This, folded with thermal momentum distributions for the scattering partners, suggests a mean dissociation lifetime $\simeq$ 20 fm/c. Therefore, the ``abnormal'' J/$ψ$ suppression seen in recent Pb+Pb experiments seems to owe to expected…
We present our results on charmonium production at the Large Hadron Collider energies within the comover interaction model. The formalism includes both comover dissociation of $J/ψ$'s and possible secondary $J/ψ$ production through recombination. The estimation of this effect is made without involving free parameters. The comover interaction model also incorporates an analytic treatment of initial-state nuclear shadowing. With these tools, the model successfully describes the centrality, transverse momentum and rapidity dependence of the experimental data from PbPb collisions at the LHC energy…
A kinetic equation approach is applied to model anomalous J/psi suppression at RHIC and SPS by absorption in a hadron resonance gas which successfully describes statistical hadron production in both experiments. The puzzling rapidity dependence of the PHENIX data is reproduced as a geometric effect due to a longer absorption path for J/psi production at forward rapidity.
We study the charmonium dissociation in the hot medium with finite baryon chemical potential $μ_B$. Charmonium bound states are dissociated in the medium by the color screening effect and the random scatterings with thermal partons, which are included in the real and imaginary parts of the potential respectively. $J/ψ$ fraction in the $c\bar c$ pair defined to be the quantum overlap between the wave package and the wave function of $J/ψ$ eigenstate decreases with time due to the complex potentials. When $μ_B$ is large compared with the medium temperature, the Deybe mass is increased evidently.…
We study the production of cc~ pairs in nuclear reactions at SPS energies within the covariant transport approach HSD. The production of cc~ is treated perturbatively employing experimental cross sections while the interactions of cc~ pairs with baryons are included by conventional cascade-type two-body collisions. Adopting 6 mb for the cc~-baryon cross sections the data on J/Ψsuppression in p+A reactions are reproduced in line with calculations based on the Glauber model. Additionally the dissociation of the cc~ pairs by strings is included in a purely geometrical way. We find good agreement …
The charmonium states with their different binding energies and radii dissolve at different temperatures of the medium produced in relativistic heavy-ion collisions. Relative yields of charmonium and thus their survival have potential to map the properties of Quark Gluon Plasma. In this study, we estimate the combined effect of color screening, gluon-induced dissociation and recombination on charmonium production in heavy-ion collisions (Pb+Pb ions) at centre of mass energy ($\sqrt{s_{\rm NN}}$) = 5.02 TeV. The rate equations of dissociation and recombination are solved separately with a 2-dim…
We study the properties of charmonium states at finite temperature in quenched lattice QCD on large and fine isotropic lattices. We perform a detailed analysis of charmonium correlation and spectral functions both below and above Tc. Our analysis suggests that the S wave states disappear at about 1.5 Tc. The charm diffusion coefficient is estimated and found to be approximately 1/πT at 1.5Tc {\leq} T {\leq} 3Tc.
Heavy quark and charmonium production as well as their space-time evolution are studied in transport simulations of heavy-ion collisions at RHIC and LHC. In the partonic transport model Boltzmann Approach of MultiParton Scatterings (BAMPS) heavy quarks can be produced in initial hard parton scatterings or during the evolution of the quark-gluon plasma. Subsequently, they interact with the medium via binary scatterings with a running coupling and a more precise Debye screening which is derived from hard thermal loop calculations, participate in the flow and lose energy. We present results of th…
A collision of a light meson and a charmonium produces quarks and antiquarks first, then the charm quark fragments into a charmed hadron, and finally three or more mesons are produced. This is the mechanism that we consider and propose to understand the prompt-J/psi nuclear modification factor in the range of J/psi transverse momentum from 10 GeV/c to 18 GeV/c, as measured by the CMS Collaboration and the ATLAS Collaboration. Unpolarized cross sections are derived and calculated for the reactions pion+charmonium ->H_c+X with H_c being a charmed meson. Numerical cross sections are parametrized …
In the energy range of RHIC and LHC the mechanisms of nuclear suppression of charmonia are expected to be strikingly different from what is known for the energy of the SPS. One cannot think any more of charmonium produced on a bound nucleon which then attenuates as it passes through the rest of the nucleus. The coherence length of charmonium production substantially exceeds the nuclear radius in the new energy range. Therefore the production amplitudes on different nucleons, rather than the cross sections, add up and interfere, i.e. shadowing is at work. So far no theoretical tool has been ava…
We analyze the transverse momentum distribution of $J/ψ$ mesons produced in Au + Au collisions at the top RHIC energy within a blast-wave model that accounts for a possible inhomogeneity of the charmonium distribution and/or flow fluctuations. The results imply that the transverse momentum spectra of$J/ψ$, $ϕ$ and $Ω$ hadrons measured at the RHIC can be described well if kinetic freeze-out takes place just after chemical freeze-out for these particles.
We investigate $J/ψ$ suppression in ultrarelativistic heavy ion collisions within a generalized GLAUBER model and compare results of a hadronic comover scenario with those of a quark plasma scenario where conditions for MOTT dissociation of charmonium are fulfilled locally at the short time scales before hadronization. We study possible consequences for the theoretical description to be drawn from the observation of ``anomalous'' thresholds in the $J/ψ$ suppression pattern by the NA50 collaboration.
We discuss charmonium production in proton-nucleus collisions at RHIC energies under the assumption of xF and x2 scaling. We find that all the ambiguities due to energy loss are gone at this energy and therefore data will reveal the scaling law, if any. These p-A data will also be crucial to interpret nucleus-nucleus data with respect to a possible formation of a quark gluon plasma because the extrapolations for charmonium production from the present p-A data to RHIC energies, based on the two scaling laws, differ by a factor of four.
We study the charmonium dissociation in a strongly coupled chiral plasma in the presence of magnetic field and axial charge imbalance. This type of plasma carries "anomalous flow" induced by the chiral anomaly and exhibits novel transport phenomena such as chiral magnetic effect. We found that the "anomalous flow" would modify the charmonium color screening length by using the gauge/gravity correspondence. We derive an analytical expression quantifying the "anomalous flow" experienced by a charmonium for a large class of chiral plasma with a gravity dual. We elaborate on the similarity and {\i…
The production of charmonia is investigated for heavy-ion collisions from SPS to RHIC energies. Our approach incorporates two sources of $J/Ψ$ yield: (i) a direct contribution arising from early (hard) parton-parton collisions, subject to subsequent nuclear absorption, quark-gluon plasma and hadronic dissociation, and (ii) statistical production at the hadronization transition by coalescence of $c$ and $\bar{c}$ quarks. Within an expanding thermal fireball framework, the model reproduces $J/Ψ$ centrality dependencies observed at the SPS in Pb-Pb and S-U collisions reasonably well. The study of…
Hadrons produced in high-energy heavy-ion collisions can suppress the production of J/psi and other charmonium states by charmonium spontaneous dissociation as the hot hadronic environment alters the interaction between the charm quark and charm antiquark. Furthermore, hadrons can thermalize a charmonium to excite it to higher charmonium states which subsequently dissociate spontaneously. They can also collide with a charmonium to lead to its prompt dissociation into an open charm pair.
The production of charmonia in relativistic heavy-ion collisions is formulated within the framework of a quantum kinetic theory simultaneously accounting for breakup and recombination processes. The survival probability of J/Psi mesons is evaluated for a Mott-Hagedorn resonance gas, whereby the pattern of anomalous J/Psi suppression at CERN-SPS can be explained by a strong coupling to open-charm states and their in-medium modification. Recent data for charmonium suppression from Au-Au collisions at RHIC are discussed.
A diagrammatic approach to quark exchange processes in meson-meson scattering is applied to the case of inelastic reactions of the type $(Q\barQ)+(q\barq)\rightarrow (Q\barq) + (q\barQ)$, where $Q$ and $q$ refer to heavy and light quarks, respectively. This string-flip process is discussed as a microscopic mechanism for charmonium dissociation (absorption) in hadronic matter. The cross section for the reaction $J/ψ+ π\to D+ \bar D$ is calculated using a potential model, which is fitted to the meson mass spectrum. The temperature dependence of the relaxation time for the $\J/Psi$ distribution i…
We investigate the in-medium modification of pseudoscalar and vector mesons in a QCD motivated chiral quark model by solving the Dyson-Schwinger equations for quarks and mesons at finite temperature for a wide mass range of meson masses, from light (pi, rho) to open-charm (D, D*) states. At the chiral / deconfinement phase transition, the quark-antiquark bound states enter the continuum of unbound states and become broad resonances (the hadronic Mott effect). We calculate the in-medium cross sections for charmonium dissociation due to collisions with light hadrons in a chiral Lagrangian approa…
Finite temperature lattice QCD indicates that the charmonium ground state J/psi can survive in a quark-gluon plasma up to 1.5 T_c or more, while the excited states chi_c and psi-prime are dissociated just above T_c. We assume that the chi_c suffers the same form of suppression as that observed for the psi-prime in SPS experiments, and that the directly produced J/psi is unaffected at presently available energy densities. This provides a parameter-free description of J/psi and psi-prime suppression which agrees quite well with that observed in SPS and RHIC data.
We discuss features of charmonium suppression at $\sqtr{s} = 200$ GeV within the framework of the Glauber-Gribov theory and the comovers interaction model. The latter approach has been extended by allowing for secondary charmonium production due to recombination of $c\bar{c}$ pairs in the medium, estimated from pp data at the same bombarding energy. Centrality and rapidity dependence of the nuclear modification factor for J/psi in d+Au, Cu+Cu and Au+Au collisions at RHIC are reproduced without fitting a single model parameter. A strong suppression of J/psi is predicted for LHC energies.
The charmonium dissociation by mesons in relativistic heavy-ion reactions is analyzed within the Regge approach. It is shown that the inclusion of the initial and final state interactions in the dissociation of J/Psi to bar{D}* D* close to threshold increases the cross section significantly and can not be neglected in comparison to the total dissociation rate. This is due to resonant bar{D}*-D* interactions in sqrt{s} close to the masses of the Psi(4.04) and Psi(4.16) mesons. We also investigate thermal effects of the (c bar{c}) width for such processes in the medium. All these effects change …
Thirty years ago, Matsui and Satz proposed the $J/ψ$ destruction as a signal of a Quark Gluon Plasma (QGP) formation, due to the Debye screening between the pair c-cbar. At the light of the recent experimental data, I review the different effects on $J/ψ$ production, from SPS to LHC energies, distinguishing between Cold Nuclear Matter (CNM) and QGP effects. Different possibilities and explanations for the available experimental data are discussed. Model predictions for the arriving LHC data are also presented.
We calculate the production of large-pTcharmonium and narrow resonance state (exotic charmonium) in proton-proton, proton-nucleus, and nucleus-nucleus collisions with the semi-coherent two-photon interactions at Relativistic Heavy Ion Collider (RHIC), Large Hadron Collider (LHC), and Future Circular Collider (FCC) energies. Using the large quasi-real photon fluxes, we present the γγ->H differential cross section for charmonium and narrow resonance state production at large transverse momentum in ultra-peripheral heavy ion collisions. The numerical results demonstrate that the experimental stud…
We derive the spin-dependent Bethe-Salpeter equation for $q\bar{q}$ bound state at finite temperature in the ladder and cross box diagram approximations. The imaginary time formalism is adopted in the adiabatic approximation where the flux tube thermal excitation is separated from the thermal excitation of the constituent quarks. The thermal excitation of the flux tube is implemented by using a temperature dependent potential inferred from the lattice gauge calculations. The thermal excitations of the constituent quarks are evaluated by summing Matsubara frequencies. The resultant equation is …
In this short review we summarize experimental information and theoretical results for the low-energy dissociation cross sections of charmonia by light hadrons. These cross sections are required for the simulation of charmonium absorption through collisions with comovers in heavy ion collisions, which competes with quark-gluon plasma production as a charmonium-suppression mechanism. If the cross sections are sufficiently large these dissociation reactions may be misinterpreted as an effect of quark-gluon plasma production. Theoretical predictions for these RHIC-related processes have used vari…
We have developed a hydrodynamic model to study sequential melting of charmonium states in an expanding QGP medium. According to the initial fluid temperature profile, $J/ψ$'s are randomly distributed in the transverse plane. As the fluid evolve in time, the free streaming $J/ψ$'s are suppressed if the local fluid temperature exceed a critical temperature. PHENIX data on the centrality dependence of $J/ψ$ suppression in Au+Au collisions at mid-rapidity are explained by sequential melting of the charmonium states, $χ_c$, $ψ\prime$ and $J/ψ$, in the expanding medium. The critical temperatures $T…
We investigate charmonium production in the hot medium created by heavy-ion collisions by setting up a framework in which in-medium charmonium properties are constrained by thermal lattice QCD (lQCD) and subsequently implemented into kinetic approaches. A Boltzmann transport equation is employed to describe the time evolution of the charmonium phase space distribution with the loss and gain term accounting for charmonium dissociation and regeneration (from charm quarks), respectively. The momentum dependence of the charmonium dissociation rate is worked out. The dominant process for in-medium …
We study the properties of charmonium in a strongly coupled QCD-like plasma at finite momentum. As a basis for this study, a "bottom-up" holographic model is used which has been previously shown to reproduce charmonium phenomenology in vacuum and give a reasonable dissociation temperature at zero momentum. The finite momentum spectral functions are presented and found to be consistent with recent lattice results. The in-medium dispersion relation and momentum dependence of decay width of J/Psi have also been studied. We find no signature of a subluminal limiting velocity from the dispersion re…
Recent experimental and theoretical studies suggest that the quarkonia suppression in a thermal QCD medium created at heavy ion collisions is a complex interplay of various physical processes. In this article we put together most of these processes in a unified way to calculate the charmonium survival probability (nuclear modification factor) at energies available at relativistic heavy ion collider (RHIC) and large hadron collider (LHC) experiments. We have included shadowing as the dominant cold nuclear matter (CNM) effect. Further, gluo-dissociation and collision damping has been included wh…
In this paper we propose the study of the photoproduction of charmoniumlike states in $pp$ collisions at RHIC and LHC energies and estimate the rapidity distribution and total cross sections for the production of the exotic hadrons $Y(3940)$, $X(3915)$, $Z(4430)$ and $Z_c(3900)$. We demonstrate that the experimental analysis of this process can provide complementary and independent checks on these states, and help to understand their underlying nature.
We study the centrality dependence to be expected if only charmonium production in the corona survives in high energy nuclear collisions, with full suppression in the hot, deconfined core. To eliminate cold nuclear matter effects as far as possible, we consider the ratio of charmonium to open charm production. The centrality dependence of this ratio is found to follow a universal geometric form, applicable to both RHIC and LHC in collisions at central and forward rapidities.
Heavy ion collisions, produced in particle accelerators, lead to the formation of a new state of matter, known as the quark gluon plasma. It is not possible to observe directly the plasma, where quarks and gluons are not confined into hadrons. All the available information comes from the particles that reach the detectors after the strongly interacting matter hadronizes. Among those particles, one that plays an important role is the charmonium J/$ψ$ heavy meson, made of a $ c \bar c$ quark anti-quark pair. The fraction of such particles produced in a heavy ion collision is related to the disso…
In this contribution we summarize experimental information and theoretical results for the dissociation cross sections of charmonium by light hadrons. Theoretical predictions for these RHIC-related processes differ by orders of magnitude over the physically relevant energy range. The results found by the author and collaborators using a constituent interchange model, which predicts cross sections in the mb region near threshold, are discussed in more detail.
Following a recent work on equation of state for strongly interacting quark-gluon plasma [J. Phys. G: Nucl. Part. Phys. 32, 993 (2006)], we revisited the equation of state by incorporating the non-perturbative effects in the deconfined plasma phase. Our results on thermodynamic observables viz. pressure, energy density, speed of sound etc. nicely fit with the lattice equation of state for gluon, massless and as well massive flavored plasma. Motivated by this agreement with lattice results, we have employed our equation of state to estimate the quarkonium suppression in an expanding, dissipativ…
We present a holographic bottom up model for the thermal behavior of $ c \bar c$ vector mesons in a finite temperature and density plasma. There is a clear physical interpretation for the three imput energy parameters of the model. Two of them are related to the mass spectrum of the heavy meson. Namely the quark mass and the string tension of the quark anti-quark interaction. The third parameter is a large energy scale associated with the non-hadronic meson decay. In such a process the heavy meson is transformed into a much lighter state by electroweak processes. The corresponding transition a…
The formation and suppression dynamics of J/Psi, Chi_c and Psi-Prime mesons is studied within the HSD transport approach for Au+Au reactions at the top RHIC energy of sqrt(S)=200 GeV. Two prominent models, which have been discussed for more than a decade, are incorporated, i.e. the 'hadronic comover absorption and reformation' model as well as the 'QGP threshold' scenario, and compared to available experimental data. Our studies demonstrate that both scenarios - compatible with experimental observation at SPS energies - fail severely at RHIC energies. This combined analysis - together with the…
$J/Ψ$ dissociation in collisions with nucleons is studied within a boson exchange model and the energy dependence of the dissociation cross section is calculated from the threshold for $Λ_c{\bar D}$ production to high energies. We illustrate the agreement of our results with calculations based on short distance QCD and Regge theory. The compatibility between our calculations and the data on $J/Ψ$ photoproduction on a nucleon is discussed. We evaluate the elastic $J/Ψ{+}N$ cross section using a forward dispersion relation and demonstrate the overall agreement with the predictions from QCD sum r…
We consider the charmonium production in thermalized hadronic medium created in ultrarelativistic heavy ion collisions at LHC energy. The calculations for the secondary $J/ψ$ and $ψ^,$ production by $D\bar D$ annihilation are performed within a kinetic model taking into account the space-time evolution of a longitudinally and transversely expanding medium. We show that the secondary charmonium production appears almost entirely during the mixed phase and it is very sensitive to the charmonium dissociation cross section with co-moving hadrons. Within the most likely scenario for the dissociatio…
We consider the production and decay of the $χ_2$ charmonium state in polarized and unpolarized $pp$ collisions at RHIC in the framework of an effective theory based on the QCD multipole expansion. We find that the angular distribution in the decay of the produced charmonium, $χ_2 \to J/ψ+ γ$, in the unpolarized case allows us to distinguish clearly between the color singlet and color octet production mechanisms. Once the production mechanism is known, the angular distribution in the polarized case can be used to measure the polarized gluon distribution in the proton, $ΔG(x)$.
A kinetic-rate equation approach in a thermally expanding medium is employed to calculate the evolution of charmonium and bottomonium distributions in heavy-ion collisions. The equilibrium properties of the quarkonia are taken from in-medium spectral functions which are schematically constrained by euclidean correlators from lattice QCD. The initial conditions for the rate equation (heavy-flavor cross sections, nuclear absorption) and the thermal evolution are constrained by data as available. After fixing two free parameters to describe charmonium data at SPS and RHIC, the predictions for LHC…
We present predictions for the J/psi and rho meson production in the heavy ion ultraperipheral collisions (UPC) for the current energy 2.76 TeV at the LHC. Both total cross sections and cross sections with the neutron emission from one or both nuclei are presented. We also analyse the RHIC rho meson photoproduction data and emphasize importance of these data to test the current model for nucleus break up in UPC.
Using the two-component model that includes charmonium production from initial nucleon-nucleon hard scattering and regeneration in the produced quark-gluon plasma, we study $J/ψ$ production in heavy ion collisions at SPS, RHIC and LHC. For the expansion dynamics of produced hot dense matter, we use a schematic viscous hydrodynamic model with the specific shear viscosity taken, respectively, to be twice and ten times the lower bound of $1/4π$ suggested by the Ads/CFT correspondence in the quark-gluon plasma and in the hadron gas. For the initial dissociation and the subsequent thermal decay of …
We study charmonia in electromagnetic and rotational fields in the frame of a potential model. Different from the temperature field which is isotropic and leads to the well-known charmonium dissociation, the electromagnetic and rotational fields break down the radial symmetry, and the competition between strong interaction and electromagnetic and rotational interaction in the direction of Lorentz force makes the charmonia transit from an isotropic bound state of strong interaction with positive binding energy to an anisotropic bound state of electromagnetic and rotational interaction with nega…
We estimate the energy of the lowest Charmonium and Upsilon states with hybrid admixtures using the method of QCD Sum Rules. Our results show that the $Ψ'(2S)$ and $Υ(3S)$ states both have about a 50% admixture of hybrid and meson components. From this we find explanations of both the famous $ρ-π$ puzzle for Charmonium, and the unusual pattern of $σ$ decays that have been found in $Υ$ decays. Moreover, this picture can be used for predictions of heavy quark production with the octet model for RHIC.
The J/Ψ(1S) and Ψ'(2S) production near threshold in antiproton-nucleus reactions is calculated on the basis of the Glauber model. The model takes into account the antiproton (pre)absorption, proton Fermi motion, and charmonium formation length. We confirm earlier prediction that the charmonium production in $\bar pA$ collisions at $p_{lab}=3-10$ GeV/c is not influenced by formation length effects and is very well suited to determine the genuine charmonium-nucleon dissociation cross sections. The comparison is performed with the J/Ψphotoproduction at high energies, where formation length effect…
Transport and Langevin equations are employed to study hadronic medium effects on charmonium elliptic flows in heavy-ion collisions. In Pb-Pb collisions, the anisotropic energy density of the quark-gluon plasma (QGP) in the transverse plane is transformed into hadron momentum anisotropy after the phase transition. Charmonia with high transverse momentum $p_T$ are produced via the primordial hard process and undergo different degrees of dissociation along different paths in the QGP. They then scatter with light hadrons in the hadron phase. Both contributions to the charmonium elliptic flows are…
Applying the HSD transport approach to charmonium dynamics within the 'hadronic comover model' and the 'QGP melting scenario', we show that the suppression pattern seen at RHIC cannot be explained by the interaction with baryons, comoving mesons and/or by color screening mechanism. The interaction with hadrons in the late stages of the collision (when the energy density falls below the critical) gives a sizable contribution to the suppression. On the other hand, it does not account for the observed additional charmonium dissociation and its dependence on rapidity. Together with the failure of …
We calculate the centrality dependence for coherent photoproduction of very low-$p_{T}$ $J/ψ$ at Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC) energies within the impact parameter dependent saturated color dipole model. By using the large equivalent photon fluxes, we present the differential cross section of very low-$p_{T}$ $J/ψ$ produced by coherent photonuclear in peripheral heavy-ion collisions. The numerical results demonstrate that our calculation are agree with $J/ψ$ data in peripheral heavy ion collisions at Relativistic Heavy Ion Collider (RHIC) energies.
We study the evolution of charmonia as they collide with the constituents of the fireball produced in high-energy nucleus-nucleus collisions. The latter evolves in a manner controlled by the equation of state as given by lattice QCD, and is constructed in such a way that the observed hadronic spectra are correctly reproduced. A kinetic description of charmonium interactions with both quark-gluon and hadronic degrees of freedom allows to study in detail the evolution in different regimes, controlled by collision energy, kinematics and geometry. The data collected at the CERN-SPS accelerator are…
Charmonium production in heavy-ion collisions is investigated within a kinetic theory framework incorporating in-medium properties of open- and hidden-charm states in line with recent QCD lattice calculations. A continuously decreasing open-charm threshold across the phase boundary of hadronic and quark-gluon matter is found to have important implications for the equilibrium abundance of charmonium states. The survival of $J/ψ$ resonance states above the transition temperature enables their recreation also in the Quark-Gluon Plasma. Including effects of chemical and thermal off-equilibrium, we…
Experiments with gold-gold collisions at RHIC have revealed (i) stronger suppression of charmonium production at forward rapidity than at midrapidity and (ii) the similarity between the suppression degrees at RHIC and SPS energies. To describe these findings we employ the model that includes nuclear shadowing effects, calculated within the Glauber-Gribov theory, rapidity-dependent absorptive mechanism, caused by energy-momentum conservation, and dissociation and recombination of the charmonium due to interaction with co-moving matter. The free parameters of the model are tuned and fixed by com…
