A theoretical derivation of photon bremsstrahlung, induced by the interactions of an energetic quark in a hot and dense quark-gluon plasma, is given in the framework of the reaction operator approach. For the physically relevant case of hard jet production, followed by few in-medium interactions, we find that the Landau-Pomeranchuk-Migdal suppression of the bremsstrahlung photon intensity is much stronger than in the previously discussed limit of on-shell quarks and a large number of soft scatterings. We present the first systematic study of direct photon production in minimum bias d+Cu and d+Au and central Cu+Cu and Au+Au heavy ion collisions at the Relativistic Heavy Ion Collider at center of mass energies of 62.4 GeV and 200 GeV. We find that the contribution of the final-state photon production at pT < 5 GeV is limited to 35%, and at high transverse momenta, the modification of the direct photon cross section is dominated by initial-state cold nuclear matter effects.
We present a model for radiative energy loss of heavy quarks in quark gluon plasma which incorporates coherence effects. We then study its consequences on the radiation spectra as well as on the nuclear modification factor of open heavy mesons produced in ultrarelativistic heavy ion collisions.
The estimate based on the parton model is made on the rate of production of Super Heavy Particle ( SHP ) in subthreshold collision of heavy ions at LHC. For the one month run of lead-lead collision the yield of 16 TeV particle is of the order of 70 per year.
Some recent experimental results obtained in collisions of heavy nuclei ($\sqrt{s}=200$ GeV) at BNL Relativistic Heavy-Ion Collider (RHIC) are discussed. The probes of dense matter created in heavy-ion collision by quarkonia, $D$ and $B$ mesons containing heavy charm and beauty quarks are considered. The centrality, rapidity and transverse momentum dependences of the nuclear modification factor and elliptic flow coefficient are presented and their possible theoretical interpretation is provided.
We review various production mechanisms of photons and small mass dileptons at large transverse momentum in heavy ion collisions at the LHC. Their relevance as a signal for quark-gluon plasma formation is discussed.
A simple geometrical model (often quoted in literature as the Glauber model) of heavy ion collisions is recapitulated. It is shown that the transverse energy distribution of heavy ion collisions follow the geometry of the collision. An extension of the model to include rapidity and transverse mass particle spectra is discussed.
From existing hadron and heavy ion collisions data on \bar{p}/p central production we estimate the value of the percolation parameter at RHIC energies.
Recent work on chemical equilibrium in heavy ion collisions is reviewed. The energy dependence of thermal parameters is discussed. The centrality dependence of thermal parameters at SPS energies is presented.
Selected topics in the field of relativistic heavy-ion collisions are reviewed f rom the 15 year research programme at the SPS at CERN and the AGS at BNL, and from the first run of the Relativistic Heavy-Ion Collider at BNL.
We discuss the model predictions for antibaryon/baryon production ratios in high energy heavy ion collisions. The role of string junction mechanism of baryon number transfer seems to be very important here and we consider some quantitative results.
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 consider (anti-)baryons production in heavy ion collisions as production of topological defects during the chiral phase transition. Non-zero quark masses which explicitly break chiral symmetry supress the (anti-)baryon density. Hardly any (anti-)baryons will be produced in the central rapidity region of a heavy ion collision.
We study the effect of energy loss on charm and bottom quarks in high-energy heavy-ion collisions including hadronization, longitudinal expansion and partial thermalization. We consider in detail the detector geometry and single lepton energy cuts of the ALICE and CMS detectors at the Large Hadron Collider (LHC) to show the large suppression of high $p_T$ heavy quarks and the consequences of their semileptonic decays.
The simple method for simulation of ``thermal'' hadron spectra in ultrarelativistic heavy ion collisions including longitudinal, transverse and elliptic flow is developed. The model is realized as fast Monte-Carlo event generator.
Some topics on heavy-ion collisions are reviewed with emphasis on those which are expected to be specially relevant at the Large Hadron Collider programme.
We estimate the impact parameter dependence of the production cross section for $η_c$ and $η_b$ mesons in peripheral heavy-ion collisions collisions. Total and elastic $γγ$ cross sections are calculated in an equivalent photon approximation.
We estimate the production rates of supersymmetric particles in central heavy-ion collisions at LHC. The parton cascade model is used to seek for possible collective phenomena which enlarge the production probability of very heavy particles. Even if there is some indication of such cooperative effects, higher energy and higher luminosity of proton beams at LHC disfavor heavy-ion reactions in the search for supersymmetric particles.
Various forms of matter may be produced in ultra-relativistic heavy ion collisions. These are the Quark Gluon Plasma, the Color Glass Condensate, the Glasma and Quarkyonic Matter. A novel effect that may be associated with topological charge fluctuations is the Chiral Magnetic Effect. I explain these concepts and explain how they may be seen in ultra-relativistic heavy ion collisions.
We describe updated calculations of $Q \bar Q$ production in $pp$ and $π^- p$ interactions. We compare these results to total cross section data and discuss how the baseline cross sections extrapolate to heavy ion collider energies. We touch upon the differences between leading and next-to-leading order heavy quark production. Finally, we discuss the implications of our calculations for quarkonium production. Our discussion here focuses on bottom quarks.
The method for simulation of medium-induced rescattering and energy loss of hard partons in ultrarelativistic heavy ion collisions is developed. The model is realized as fast Monte-Carlo tool implemented to modify standard PYTHIA jet event.
We analyse the cluster structure of the final multihadron states resulting from heavy ion collisions using the concept of Jaynes - Shannon entropy. Further evidence for an interesting differentiation of events is provided.
We present a simple model with string absorption and percolation to describe the J/psi suppression in heavy ion collisions. The NA50 data are fairly well explained by the model.
Some of the new developments in the theory of heavy ion collisions are reviewed. Much of the last progress have been triggered by the high energies available at RHIC. In the near future, the LHC will extend the energy reach in heavy ions by a factor thirty and give access to new QCD regimes characterized by large densities and temperatures and corresponding modified evolution equations.
We investigate the impact parameter dependence of the $\cos 4ϕ$ azimuthal asymmetry for electromagnetic lepton pair production in heavy ion collisions. The asymmetry induced by linearly polarized coherent photons exhibits strong impact parameter dependence.
This is a review of the physics prospects for relativistic heavy ion collisions in the CERN Large Hadron Collider. The motivation for the study of superdense matter created in relativistic heavy ion collision is the prospect of observing a novel state of strongly interacting matter, the quark-gluon plasma. Experiments at the CERN Super Proton Synchrotron (SPS) and the Relativistic Heavy Ion Collider (RHIC) at Brookhaven have yielded important clues of the characteristic signatures of this new state. The LHC will extend the range of energy densities that can be explored and facilitate the obser…
We propose to measure the linear polarization of the external electromagnetic fields of a relativistic heavy ion through azimuthal asymmetries in dilepton production in ultraperipheral collisions. The asymmetries estimated with the equivalent photon approximation are shown to be sizable.
Magnetic monopoles may be produced by the dual Schwinger effect in strong magnetic fields. Today, the strongest known magnetic fields in the universe are produced fleetingly in heavy-ion collisions. We use the complex worldline instanton method to calculate the momentum distribution of magnetic monopoles produced in heavy-ion collisions, in an approximation that includes the effect of the magnetic field to all orders but neglects monopole self-interactions. The result saturates the preparation time-energy uncertainty principle, and yields a necessary ingredient for experimental monopole search…
The effect of collective potentials on pion spectra in ultrarelativistic heavy ion collisions is investigated. We find the effect of these potential to be very small, too small to explain the observed enhancement at low transverse momenta. (7 figures, bill be send on request)
We analyze the centrality dependence of thermal parameters describing hadron multiplicities, hadron spectra and dilepton spectra in heavy-ion collisions at SPS and RHIC energies.
Particle production mechanisms in high-energy heavy-ion collisions are reviewed in connection with recent experimental data from RHIC. Implications on mini-jet production, parton saturation and jet quenching are discussed.
It is argued that in heavy ion collisions at LHC there could be a sizeable production of baryons containing two or three heavy quarks from statistical coalescence. This production mechanism is peculiar of Quark Gluon Plasma and the predicted rates, in heavy ion collisions at LHC energy, exceed those from a purely hadronic scenario, particularly for Xi_bc and Omega_ccc. Thus, besides the interest in the discovery of these new states, enhanced ratios of these baryons over singly heavy flavoured hadrons, like B or D, in heavy ion collisions with respect to pp at the same energy, would be a clear …
We review our recent results on exclusive production of $μ^+ μ^-$, heavy quark-antiquark, and meson-antimeson pairs in ultraperipheral, ultrarelativistic heavy ion collisions.
Heavy flavor supplies a chance to constrain and improve the hadronization mechanism. We have established a sequential coalescence model with charm conservation and applied it to the charmed hadron production in heavy ion collisions. The charm conservation enhances the earlier hadron production and suppresses the later production. This relative enhancement (suppression) changes significantly the ratios between charmed hadrons in heavy ion collisions.
This is a review of numerical applications of classical gluodynamics to heavy ion collisions. We recall some results from calculations of gluon production, discuss their implications for heavy ion phenomenology, and outline a strategy to calculate the number of quark pairs produced by these classical fields.
Various aspects of the current status of ultrarelativistic heavy ion collisions are reviewed. Perspectives of heavy ion physics in the future are given as well.
We review the theoretical aspects relevant in the description of high energy heavy ion collisions, with an emphasis on the learnings about the underlying QCD phenomena that have emerged from these collisions.
The manuscript presents generalization of the Landau hydrodynamic solution for multiparticle production applied for non-central relativistic heavy ion collisions. Obtained solution enables to calculate anisotropy parameter $v_2$ for different rapidities with respect to the initial conditions for hydrodynamics.
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 collisi…
It was proposed that the electric fields may lead to chiral separation in QGP, which is called the chiral electric separation effect. The strong electromagnetic field and the QCD vacuum can both completely be produced in the off-central nuclear-nuclear collision. We used the Wood-Saxon nucleon distribution to calculate the electric field distributions of the off-central collisions. The chiral electro field spatial distribution at Relativistic Heavy-Ion Collider (RHIC) and Large Hadron Collider (LHC) energy regions are systematically studied in this paper. Compared with magnetic field spatial d…
We study the spectrum of the bremsstrahlung photons coming from the electrons and positrons, which are produced in the strong electromagnetic fields present in peripheral relativistic heavy ion collisions. We compare different approaches, making use of the exact pair production cross section in heavy ion collisions as well as the double equivalent photon approximation.
We perform an analysis of jet quenching in heavy and light ion collisions for scenarios without and with quark-gluon plasma formation in $pp$ collisions. We find that the results for these scenarios are very similar, and both of them are in reasonable agreement with data for heavy ion collisions. However, their results become differ significantly for light nuclei. Using the parameters fitted to heavy ion data on the nuclear modification factor $R_{AA}$, we make predictions for 0.2 and 7 TeV O+O collisions that can be verified by future experiments at RHIC and the LHC.
The diffusion coefficients of heavy quarks from the coherent color electromagnetic fields which are generated in the early stage of relativistic heavy-ion collisions are calculated at midrapidity, and compared with those obtained from collisions within a thermalized quark-gluon plasma. The coherent color fields are modeled such that they are initially longitudinal and then become isotropic. We found that the diffusion coefficients from the coherent color fields are larger than those from collisions except for very fast heavy quarks, and the color fields are less effective for heavy-quark energ…
Heavy ion collisions pose interesting challenges to quantum chromodynamics, because they probe the parton structure of the incoming nuclei at very small longitudinal momentum fractions. Combined with the large size of nuclei, this may lead to the phenomenon of gluon saturation. The Color Glass Condensate is an effective QCD description that aims to cope with such a situation. In this talk, I show how one may study heavy ion collisions in this framework.
Heavy quarks are copiously produced in ultra-peripheral heavy ion collisions. In the strong electromagnetic fields, c c-bar and b b-bar are produced by photonuclear and two-photon interactions; hadroproduction can occur in grazing interactions. We present the total cross sections, quark transverse momentum and rapidity distributions, as well as the Q Q-bar invariant mass spectra from the three production channels. We consider AA and pA collisions at the Relativistic Heavy Ion Collider and Large Hadron Collider. We discuss techniques for separating the three processes and describe how the AA to…
The heavy quark production in ultraperipheral heavy ion collisions is investigated, in particular we focus on the results from the coherent interactions given by the two-photon process. One addresses the heavy quark total cross sections at photon level considering the saturation model and the BFKL dynamics in the color dipole picture. The corresponding cross sections at nuclear level are presented. It is verified that the QCD dynamics implies an enhancement of the cross section in comparison with previous calculations.
I argue that perturbative scattering of quarks and gluons are incompatible with lattice and heavy ion data on QGP properties. The non-perturbative mechanisms for quasiparticle rescattering and quark production are briefly discussed, as well as experiments needed to measure matter anisotropy and quark density at early stages of the collisions.
