The stochastic dynamics of heavy quarks in the fireball produced in heavy-ion collisions is followed through numerical simulations based on the Langevin equation. The modification of the final p_T spectra (R_AA) of c and b quarks, hadrons and single-electrons with respect to pp collisions is studied. The transport coefficients are evaluated treating separately the contribution of soft and hard collisions. The initial heavy-quark spectra are generated according to NLO-pQCD, accounting for nuclear effects through recent nPDFs. The evolution of the medium is obtained from the output of two hydro-codes (ideal and viscous). The heavy-quark fragmentation into hadrons and their final semileptonic decays are implemented according to up to date experimental data. A comparison with RHIC data for non-photonic electron spectra is given.
A snapshot of the results for heavy-flavour observables in heavy-ion (AA) collisions at RHIC and LHC obtained with our transport calculations is displayed. The initial charm and beauty production is simulated through pQCD tools (POWHEG+PYTHIA) and is validated through the comparison with data from pp collisions. The propagation of c and b quarks in the medium formed in heavy-ion collisions is studied through a transport setup based on the relativistic Langevin equation. With respect to past works we perform a more systematic study, providing results with different choices of transport coeffici…
The stochastic dynamics of c and b quarks in the fireball created in nucleus-nucleus collisions at RHIC and LHC is studied employing a relativistic Langevin equation, based on a picture of multiple uncorrelated random collisions with the medium. Heavy-quark transport coefficients are evaluated within a pQCD approach, with a proper HTL resummation of medium effects for soft scatterings. The Langevin equation is embedded in a multi-step setup developed to study heavy-flavor observables in pp and AA collisions, starting from a NLO pQCD calculation of initial heavy-quark yields, complemented in th…
The propagation of the heavy quarks produced in relativistic nucleus-nucleus collisions at RHIC and LHC is studied within the framework of Langevin dynamics in the background of an expanding deconfined medium described by ideal and viscous hydrodynamics. The transport coefficients entering into the relativistic Langevin equation are evaluated by matching the hard-thermal-loop result for soft collisions with a perturbative QCD calculation for hard scatterings. The heavy-quark spectra thus obtained are employed to compute the differential cross sections, the nuclear modification factors R_AA and…
We study the stochastic dynamics of c and b quarks, produced in hard initial processes, in the hot medium created after the collision of two relativistic heavy ions. This is done through the numerical solution of the relativistic Langevin equation. The latter requires the knowledge of the friction and diffusion coefficients, whose microscopic evaluation is performed treating separately the contribution of soft and hard collisions. The evolution of the background medium is described by ideal/viscous hydrodynamics. Below the critical temperature the heavy quarks are converted into hadrons, whose…
The relativistic diffusion process of heavy quarks is formulated on the basis of the relativistic Langevin equation in Itô discretization scheme. The drag force inside the quark-gluon plasma (QGP) is parametrized according to the formula for the strongly coupled plasma obtained by the AdS/CFT correspondence. The diffusion dynamics of charm and bottom quarks in QGP is described by combining the Langevin simulation under the background matter described by the relativistic hydrodynamics. Theoretical calculations of the nuclear modification factor R_{AA} and the elliptic flow v_{2} for the single …
A Langevin equation of heavy quarks in high-temperature quark-gluon plasma is derived. The dynamics of heavy quark color is coupled with the phase space dynamics and causes a macroscopic superposition state of heavy quark momentum. Decoherence of the superposition state allows one to use a classical description. The time scale of decoherence gives an appropriate discretization time scale $Δt\sim \sqrt{M/C_{\rm F}γ}$ for the classical Langevin equation, where $M$ is heavy quark mass and $γ$ is heavy quark momentum diffusion constant.
We present a new model for the description of heavy-flavor hadronization in relativistic heavy-ion collisions. We explore its effect on the charmed hadron yields and kinematic distributions once the latter is applied at the end of transport calculations used to simulate the propagation of heavy quarks in the deconfined fireball produced in the collision. The model is based on the formation of color-singlet clusters through the recombination of charm quarks with light antiquarks or diquarks from the same fluid cell. This local mechanism of color neutralization leads to a strong space-momentum c…
We calculate the inclusive heavy quark production cross section for proton-nucleus collisions at high energies. We perform calculation in a quasi-classical approximation (McLerran-Venugopalan model) neglecting all low-x evolution effects. The derived expression for the differential cross section can be applied for studying the heavy quark production in the central rapidity region at RHIC.
We present a study of the heavy-flavor dynamics in nucleus-nucleus collisions. The initial (hard) production of c and b quarks is taken from NLO pQCD predictions. The presence of a hot medium (a Quark Gluon Plasma described by hydrodynamics) affects the final spectra of open-charm (beauty) hadrons and their decay electrons with respect to what found in pp collisions. The propagation of c and b quarks in the plasma is based on a picture of multiple uncorrelated random collisions, described by a relativistic Langevin equation. A microscopic evaluation of the transport coefficients is provided wi…
The chromo-electromagnetic field is produced due to the motion of partons in a quark-gluon plasma created by relativistic heavy-ion collisions. The fluctuations in the produced chromo-electromagnetic field are important, since they cause heavy quarks to gain energy in the low velocity limit. We study the effect of such fluctuations on heavy quark diffusion in quark-gluon plasma within the framework of Langevin dynamics under the background matter described by the ($3+1$)-dimensional relativistic viscous hydrodynamics. Theoretical calculations of the nuclear modification factor ($R_{AA}$) of he…
The Langevin diffusion process of a relativistic heavy quark in a non-conformal holographic setup is discussed. The bulk geometry is a general, five-dimensional asymptotically AdS black hole. The heavy quark is described by a trailing string attached to a flavor brane, moving at constant velocity. From the equations describing linearized fluctuations of the string world-sheet, the correlation functions defining a generalized Langevin process are constructed via the AdS/CFT prescription. In the local limit, analytic expressions for the Langevin diffusion and friction coefficients are obtained i…
We present recent results for heavy-flavor observables in nucleus-nucleus collisions at LHC energies, obtained with the POWLANG transport setup. The initial creation of c-cbar and b-bbar pairs is simulated with a perturbative QCD approach (POWHEG+PYTHIA); their propagation in the medium (created in the nucleus-nucleus or in proton-nucleus collision) is studied with the relativistic Langevin equation, here solved using weak-coupling transport coefficients. Successively, the heavy quarks hadronize in the medium. We compute the nuclear modification factor and the elliptic flow parameter of the fi…
By utilizing a soft-hard factorized model, which combines a thermal perturbative description of soft scatterings and a perturbative QCD-based calculation for hard collisions, we study the energy and temperature dependence of the heavy quark diffusion coefficients in Langevin dynamics. The adjustable parameters are fixed from the comprehensive model-data comparison. We find that a small value of the spatial diffusion coefficient at transition temperature is preferred by data $2πTD_{s}(T_{c}) \simeq 6$. With the parameter-optimized model, we are able to describe simultaneously the prompt $D^{0}$…
We employ a new method, "gauge cooling", to stabilize complex Langevin simulations of QCD with heavy quarks. The results are checked against results obtained with reweigthing; we find agreement within the estimated errors. The method allows us to go to previously unaccessible high densities.
We study the heavy quark evolution in a quark-gluon plasma medium within the framework of Langevin equation coupled to a (2+1)-dimensional viscous hydrodynamic model. We modify the current Langevin algorithm such that apart from quasi-elastic scattering, medium-induced radiative energy loss is incorporated as well by treating gluon radiation as an extra force term. We find a significant effect of gluon radiation on heavy quark energy loss at LHC energies. Our calculation provides a good description of the D meson suppression measured by ALICE experiment, and makes a prediction for B meson supp…
The heavy quark propagation behavior inside the quark-gluon plasma (QGP), is usually described in terms of the Boltzmann dynamics, which can be reduced to the Langevin approach by assuming a small momentum transfer for the scattering processes between heavy quarks and the QGP constituents. In this work, the temperature and energy dependence of the transport coefficients are calculated in the framework of both Boltzmann and Langevin dynamics. The derived transport coefficients are found to be systematically larger in the Boltzmann approach as compared with the Langevin, in particular in the hig…
Heavy nuclei at collider energies are a source of high energy Weizsaecker-Williams photons. This photon flux may be utilized to study high energy photon-nucleus interactions. Here we concentrate on the coherent diffractive production of heavy vector mesons on nuclear targets and show how it probes the unintegrated glue of the nucleus in the saturation domain. We present predictions for rapidity distributions of exclusive coherent J/Psi and Upsilon mesons which can be measured by the ALICE experiment at the LHC.
Quark Gluon Plasma transport coefficients for heavy quarks and quark-antiquark pairs are computed through an extension of the results obtained for a hot QED plasma by describing the heavy-quark propagation in the eikonal approximation and by weighting the gauge field configurations with the Hard Thermal Loop effective action. It is shown that such a model allows to correctly reproduce, at leading logarithmic accuracy, the results obtained by other independent approaches. The results are then inserted into a relativistic Langevin equation allowing to follow the evolution of the heavy-quark mome…
Using a model based on the Color Glass Condensate framework and the dilute-dense factorization, we systematically study the azimuthal angular correlations between a heavy flavor meson and a light reference particle in proton-nucleus collisions. The obtained second harmonic coefficients (also known as the elliptic flows) for $J/ψ$ and $D^0$ agree with recent experimental data from the LHC. We also provide predictions for the elliptic flows of $Υ$ and $B$ meson, which can be measured in the near future at the LHC. This work can shed light on the physics origin of the collectivity phenomenon in t…
We use a diagrammatic approach to study color-neutral heavy particle production in nucleus-nucleus collisions in a quasi-classical approximation without small-$x$ evolution. In order to treat the two nuclei symmetrically, we use the Coulomb gauge which gives the appropriate light cone gauge for each nucleus. The resulting cross section is factorized into a product of two Weizsäcker-Williams gluon distributions of the two nuclei when the transverse momentum of the produced scalar particle is around the saturation momentum. We confirm our results in covariant gauge where the transverse momentum …
We study the dynamics of energy loss and flow of heavy quarks produced in ultra-relativistic heavy-ion collisions within the framework of a Langevin equation coupled to a (2+1)-dimensional viscous hydrodynamic model that simulates the space-time evolution of the produced hot and dense QCD matter. The classical Langevin approach is improved such that, apart from quasi-elastic scatterings, radiative energy loss is incorporated by treating gluon radiation as an additional force term. The hadronization of emitted heavy quarks is simulated via a hybrid fragmentation plus recombination model. Our ca…
Apparently universal trends have been observed in relativistic nucleus-nucleus collisions up to RHIC energies. Here, we review these trends and we discuss their agnostic extrapolation to heavy ion collisions at the LHC.
We calculate the inclusive J/Psi production in heavy ion collisions including the effects of gluon saturation in the wave functions of the colliding nuclei. We argue that the dominant production mechanism in proton--nucleus and nucleus--nucleus collisions for heavy nuclei is different from the one in hadron-hadron interactions. We find that the rapidity distribution of primary J/Psi production is more peaked around midrapidity than the analogous distribution in elementary pp collisions. We discuss the consequences of this fact on the experimentally observed J/Psi suppression in Au-Au collision…
We calculate nuclear suppression $R_{AA}$ of heavy quarks produced from the initial fusion of partons in nucleus-nucleus collisions at RHIC and LHC energies. We take the shadowing as well as the energy loss suffered by them while passing through Quark Gluon Plasma into account. We obtain results for charm and bottom quarks at several rapidities using different mechanisms for energy loss, to see if we can distinguish between them.
An experimental overview of the energy dependence of strangeness production is presented. The strange hadrons are considered a good probe to study the QCD matter created in relativistic nucleus-nucleus collisions. The heavy-ion experiments at SPS, RHIC, and LHC have recorded a wealth of data in proton-proton, proton-nucleus and nucleus-nucleus collisions at several beam energies. In this proceeding, I discuss the invariant yield and azimuthal anisotropy measurement of strange hadrons in nucleus-nucleus collisions at SPS, RHIC, and LHC.
n these proceedings I discuss several recent developments in the physics of heavy flavor jets in heavy ion collisions. i) The dijet mass modification in nucleus-nucleus reactions has been proposed as a new observable with enhanced sensitivity to parton energy loss in nuclear matter. It also enables more precise studies of heavy quark mass effects on parton shower formation. ii) Computational techniques from soft-collinear effective theory have allowed us to bridge the gap between high energy and heavy ion QCD phenomenology. I show the first application of the semi-inclusive jet function formal…
We investigate the gluonic probe to the nucleon-nucleon short range correlation (SRC) in nucleus through heavy flavor production in deep inelastic scattering (DIS). The relevant EMC effects of $F_2^{c\bar c}$ structure function will provide a universality test of the SRCs which have been extensively studied in the quark-channel. These SRCs can also be studied through the sub-threshold production of heavy flavor in $eA$ collisions at the intermediate energy electron-ion collider, including open Charm and $J/ψ$ ($Υ$) production.
We develop a relativistic Langevin dynamics under the background of strongly interacting quark-gluon fluid described by the (3+1)-dimensional hydrodynamics. The drag force acting on charm and bottom quarks is parametrized according to the formula obtained from the anti-de-Sitter space/conformal field theory (AdS/CFT) correspondence. In this setup, we calculate the nuclear modification factor $R_{\rm{AA}}$ for the single-electrons from the charm and bottom quarks to extract the magnitude of the drag force from the PHENIX and STAR data. The $R_{\rm{AA}}$ for single-electrons with $p_{T}\geq 3$ G…
Photoproduction of heavy quarks in ultraperipheral collisions can help elucidate important features of the physics of heavy quarks in Quantum Chromodynamics (QCD). Due to the dependence on parton distributions it can also potentially offer some constraining ability in the determination of nuclear parton distributions. In the present study we consider next-to-leading order (NLO) photoproduction of heavy quarks in ultraperipheral proton-proton (pp), proton-nucleus (pA), and nucleus-nucleus (AA) collisions at the CERN Large Hadron Collider (LHC). Total cross sections and rapidity distributions ar…
We study the consequences of different realizations of diffusion processes in relativistic Langevin simulations. We elaborate on the Ito-Stratonovich dilemma by showing how microscopically calculated transport coefficients as obtained from a Boltzmann/Fokker-Planck equation can be implemented to lead to an unambiguous realization of the Langevin process. Pertinent examples within the pre-point (Ito) and post-point (Hänggi-Klimontovich) Langevin prescriptions are worked out explicitly. Deviations from this implementation are shown to generate variants of the Boltzmann distribution as the statio…
We illustrate how a generalization of the JIMWLK formalism which treats independently the direct and complex conjugate amplitudes can be used to describe semi-inclusive multiparticle production with rapidity correlations in pA collisions. The evolution equations that are obtained with this formalism are susceptible of numerical implementation as a Langevin process.
In the first part, I give a brief description of the quark-gluon plasma search at CERN and of some experimental results. In the second part, I review a dynamical model of nucleus-nucleus interactions and propose a physical interpretation of those results.
Heavy flavor measurements in high multiplicity proton-proton and proton-nucleus collisions at collider energies enable unique insights into their production and hadronization mechanism because experimental and theoretical uncertainties cancel in ratios of their cross-sections relative to minimum bias events. We explore such event engineering using the Color Glass Condensate (CGC) effective field theory to compute short distance charmonium cross-sections. The CGC is combined with heavy-quark fragmentation functions to compute $D$-meson cross-sections; for the $J/ψ$, hadronization is described e…
We discuss a number of cold nuclear matter effects that can modify open heavy flavor and quarkonium production in proton-nucleus collisions and could thus also affect their production in nucleus-nucleus collisions, in addition to hot quark-gluon plasma production. We show some results for $p+$Pb collisions at sqrt s = 5 TeV at the LHC.
The production of backward nucleons, $N(180^\circ)$, at $180^\circ$ in the nuclear target rest frame in proton-nucleus ($\mathrm{p}+A$) collisions is studied. The backward nucleons appearing outside of the kinematically allowed range of proton-nucleon ($\mathrm{p}+N$) reactions are shown to be due to secondary reactions of heavy baryonic resonances produced inside the nucleus. Baryonic resonances $R$ created in primary $\mathrm{p}+N$ reactions can change their masses and momenta due to successive collisions $R+N\rightarrow R +N $ with other nuclear nucleons. Two distinct mechanisms and kinemat…
Heavy quark production has been very well studied over the last years both theoretically and experimentally. Theory has been used to study heavy quark production in $e p$ collisions at HERA, in $pp$ collisions at Tevatron and at RHIC, in $pA$ and $dA$ collisions at RHIC and in $AA$ collisions at CERN-SPS and at RHIC. However, to the best of our knowledge, heavy quark production in $eA$ has received almost no attention. With the possible construction of a high energy electron-ion collider, updated estimates of heavy quark production are needed. We address the subject from the perspective of sat…
The binding system of a hadron and a nucleus is a topic of great interest for investigating the hadron properties. In the heavy-flavor region, the attraction between a $P(=\bar{D},B)$ meson and a nucleon $N$ can appear, where the $PN-P^\ast N$ mixing plays an important role in relation to the heavy-quark spin symmetry. The attraction can produce exotic heavy mesic nuclei that are stable against the strong decay. We study an exotic system where the $\bar{D}$ ($B$) meson and nucleus are bound. The meson-nucleus interaction is given by a folding potential with single-channel $PN$ interaction and …
We consider a possibility of capture of a heavy charged massive particle $χ^-$ by the nucleus leading to appearance of a bound state. A simple analytic formula allowing to calculate binding energies of the $Nχ^-$ bound state for different nuclei is derived. If the binding energy is sufficiently large the particle $χ^-$ is stable inside the nucleus. The probabilities of the nuclear fissions for such states are calculated. It is shown that the bound states are more stable to a possible fission in comparison to the bare nucleus. This makes an observation of this hypothetical charged massive parti…
Pion production in proton-nucleus (p+A) collisions outside the kinematical boundary of proton-nucleon (p+N) reactions, the so-called cumulative effect, is studied. Restrictions from energy-momentum conservation on the energy of pions emitted in the backward direction in the target rest frame are analyzed. It is assumed that the cumulative pions are produced in p+A reactions by heavy baryonic resonances. The baryonic resonances are first created in p+N reactions. Due to successive collisions with nuclear nucleons the masses of these resonances may then increase and, simultaneously, their longit…
This report reviews the study of open heavy-flavour and quarkonium production in high-energy hadronic collisions, as tools to investigate fundamental aspects of Quantum Chromodynamics, from the proton and nucleus structure at high energy to deconfinement and the properties of the Quark-Gluon Plasma. Emphasis is given to the lessons learnt from LHC Run 1 results, which are reviewed in a global picture with the results from SPS and RHIC at lower energies, as well as to the questions to be addressed in the future. The report covers heavy flavour and quarkonium production in proton-proton, proton-…
Electron scattering methods, involving nucleus which have little or no intrinsic deformation suggest nucleon distribution to be of Fermi type. This distribution is further parameterised as Wood Saxon (WS) distribution, where an uniform charge density with smoothed-out surface have been implemented. Incorporating shape modification in WS, earlier attempts were made to explain observables in deformed nuclear collisions, such as charged particle multiplicity. In this work, we use an alternate approach known as Nilsson model or Modified Harmonic Oscillator (MHO), to explain charged particle multip…
The cross sections for exclusive muon pair production in nucleus - nucleus collisions are calculated and several differential distributions are shown. Realistic (Fourier transform of charge density) charge form factors of nuclei are used and the corresponding results are compared with the cross sections calculated with monopole form factor often used in the literature and discussed recently in the context of higher-order QED corrections. Absorption effects are discussed and quantified. The cross sections obtained with realistic form factors are significantly smaller than those obtained with th…
Predictions on fluctuations of hadron production properties in central heavy ion collisions are presented. They are based on the Statistical Model of the Early Stage and extend previously published results by considering the strongly intensive measures of fluctuations. In several of the considered cases a significant change in collision energy dependence of calculated quantities as a result of the phase transition is predicted. This provides an opportunity to observe new signals of the onset of deconfinement in heavy ion collisions experiments.
We present a study of $τ^{+}τ^{-}$ lepton pair production in Pb+Pb collisions at $\sqrt{s_{NN}}$ = 5.5 TeV. The larger $τ^{\pm}$ mass ($\sim$ 1.77 GeV) compared to $e^{\pm}$ and $μ^{\pm}$ leads to considerably small hadronic contribution to the $τ^{+}τ^{-}$ pair invariant mass ($M$) distribution relative to the production from thermal partonic sources. The quark-anti-quark annihilation processes via intermediary virtual photon, Z and Higgs bosons have been considered for the production of $ τ^{+}τ^{-}$. We observe that the contribution from Drell-Yan process dominates over thermal yield for $τ…
We present results on rapidity and transverse momentum distributions of inclusive charm quark production in hadronic and heavy-ion collisions at RHIC and LHC energies, including the next-to-leading order, $O(α_s^3)$, radiative corrections and the nuclear shadowing effect. We determine the hadronic and the {\it effective} (in-medium) K-factor for the differential and total inclusive charm cross sections. We find the fraction of central and inelastic events that contain at least one charm quark pair at LHC energies and obtain the effective $A$-dependence of the inclusive charm production in prot…
We improve the centrality definition in impact parameter in PACIAE model responding the fact reported by the ALICE, ATLAS, and CMS collaborations that the maximum impact parameter in heavy ion collisions should be extended to 20 $fm$. Meanwhile the PACIAE program is updated to a new version of PACIAE 2.2.2 with convenience of studying the elementary nuclear collisions, proton-nucleus collisions, and the nucleus-nucleus collisions in one unified program version. The new impact parameter definition together with the optical Glauber model calculated impact parameter bin, $N_{part}$, and $N_{coll}…
We study nuclear shadowing in $J/ψ$ and $Υ$ production in hadron-nucleus interactions and in nucleus-nucleus collisions at the Relativistic Heavy Ion Collider and the Large Hadron Collider. %We define the regions in $x_f$ where nuclear shadowing begins %to set in for \jp\ and \up. As a consequence of the perturbative $Q^2$-dependence of gluon shadowing, we predict that $Υ$ production is less suppressed than the $J/ψ$. We show that antishadowing leads to enhanced \jp\ production at $x_f \lesssim 0$, an effect reduced for $Υ$ production.
The bremsstrahlung produced when heavy nuclei collide is estimated for central collisions at the Relativistic Heavy Ion Collider. Bremsstrahlung photons with energies below 100 to 200 MeV are sufficient to discern the gross features of the space-time evolution of electric charge, if they can be separated from other sources of photons experimentally. This is illustrated explicitly by considering two very different models, one Bjorken-like, the other Landau-like, both of which are constructed to give the same final charge rapidity distribution.
We explore the quark mass effects on inclusive hadron production in proton-nucleus collisions at high energies. We consider two processes. First, we compute the single inclusive cross-section for production of hadrons with open heavy flavour in the proton forward direction at leading order. Next, in the same kinematics, we calculate the heavy-quark contribution to single inclusive production of light or unidentified hadrons at next-to-leading-order. For both studies we exploit the hybrid formalism, that is the collinear factorisation on the proton side while high-density and high-energy effect…
Deep inelastic scattering on nuclei at the Electron-Ion Collider will open new opportunities to investigate the structure of matter. Heavy flavor-tagged jets are complementary probes of the partonic composition and transport coefficients of large nuclei, but introduce a new mass scale that modifies the structure of parton showers and must be carefully accounted for in perturbative calculations. In the framework of soft-collinear effective theory with Glauber gluon interactions, we present the first calculation of inclusive charm-jet and bottom-jet cross sections in electron-nucleus collisions …
We discuss the photoproduction of $Υ$ and $J/ψ$ at high energy $\bar{p}p$, $pp$ and heavy ion colliders. We predict large rates in $\bar{p}p$ interactions at the Fermilab Tevatron %and in heavy-ion interactions at the CERN LHC. These reactions can be and in $pp$ and heavy-ion interactions at the CERN LHC. The $J/ψ$ is also produced copiously at RHIC. These reactions can be used to study the gluon distribution in protons and heavy nuclei. We also show that the different CP symmetries of the initial states lead to large differences in the transverse momentum spectra of mesons
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…
A sizable rate of events, with several pairs of heavy-quarks produced contemporarily by multiple parton interactions, may be expected at very high energies as a consequence of the large parton luminosities. The production rates are enhanced in hadron-nucleus reactions, which may represent a convenient tool to study the phenomenon. We compare the different contributions to ccbar bbar pairs production due to single and double parton scatterings, in collisions of protons with nuclei at the CERN-LHC.
