One of the important findings in small colliding systems at the LHC energies is that yields of (multi-)strange hadrons enhance more rapidly than those of charged pions as functions of multiplicity. To interpret this, we develop a dynamical initialization model with core-corona picture in hydrodynamic models. We generate the initial partons using some event generator. We put them in the source...
The produced matter in the high energy nuclear collisions reinteracts and form a plasma which ultimately equilibrates and exhibits collective hydrodynamic flow.
The connection between the early gluon production in classical field simulations and hydrodynamic expansion at later times is given by the QCD kinetic theory.
I will discuss the recent progress on smooth matching between these three...
In this talk I overview the results of our studies of heavy ion collisions at RHIC BES energies in the framework of a viscous hydro + cascade model, vHLLE+UrQMD, focusing on the following phenomena:
- Lambda polarization - from RHIC BES to LHC energies
- Femtoscopic observables at RHIC BES
And discuss challenges for hydrodynamic modelling at the lower collision energies (RHIC BES, FAIR,...
A relativistic viscous hydrodynamic model plays an important role in the quantitative
understanding of the QGP bulk property.
In spite of the success of hydrodynamic models in high-energy heavy-ion collisions,
there are still several issues under discussion.
In particular, we emphasize that a numerical algorithm for solving the relativistic hydrodynamic
equation is one of the important...
Relativistic hydrodynamics has played a key role in our understanding of the novel properties of quark-gluon plasma. However, the validity of hydrodynamical models in describing the extreme conditions produced in heavy ion collisions has still not been properly justified theoretically. Even more, the gradient expansion, commonly used to derive hydrodynamics from microscopic theory, has been...
The "unreasonable effectiveness" of relativistic fluid dynamics in describing high energy heavy-ion and even proton-proton collisions will be demonstrated and discussed. Several recent ideas of optimizing relativistic fluid dynamics for the specific challenges posed by such collisions will be presented, and some thoughts will be offered why the framework works better than originally expected....
Relativistic viscous hydrodynamics consists of a set of complicated nonlinear differential equations. Nevertheless, it is possible to find simple relations between particular aspects of the initial conditions and final observables in hydrodynamic simulations of relativistic heavy ion collisions. The canonical example is the event-by-event proportionality between elliptic flow and initial...
Most of the information we have about the phases modelled by hydrodynamics in relativistic nuclear collisions comes from the analyses of hadronic collectivity. However, electromagnetic radiation (real and virtual photons) can be both penetrating and soft, and as such opens a unique window to the space-time regions that are opaque to hadrons. In this talk, we will review how measurements of...
A primary goal of heavy-ion physics is the measurement of the fundamental properties of the quark-gluon plasma (QGP), notably its transport coefficients and initial state properties. Since these properties are not directly measurable, one relies on a comparison of experimental data to computational models of the time-evolution of the collision to connect measured observables to the properties...
The observation of a finite global polarization in agreement with
theoretical predictions has opened a new dimension in relativistic
heavy ion physics as well as in relativistic hydrodynamics, with
several intriguing connections to chiral and electromagnetic effects.
Very recent experimental observations seem to challenge the
hydrodynamic predictions. In this talk, the status of the theory...
We calculate the $\delta f$ correction to the one particle distribution function in
presence of magnetic field and non-zero shear viscosity within the relaxation time approximation. The $\delta f$ correction is found to be electric charge dependent. Subsequently, we also calculate one longitudinal and four transverse shear viscous coefficients as a function of dimensionless Hall parameter...
In recent years heavy-ion collisions have noted that a preference for both a deformed proton and deformed nuclei are seen in comparing flow observables to relativistic viscous hydrodynamic calculations. Thus far, all deformations of nuclei have only considered the ground state of the nucleus. In the case of XeXe collisions, it was found that the deformed Xenon nucleus increase elliptical flow...
We study the role of fluctuations in relativistic fluid dynamics. We consider two issues, long-time tails in current-current correlation functions, and simulations of baryon diffusion in the vicinity of a critical point.
Strongly interacting matter at high temperatures and large densities can be created and carefully studied under laboratory conditions in high-energy collisions of heavy atomic nuclei. Especially, heavy quarks (charm and beauty) provide particular good probes to study the QCD plasma and its evolution since they are predominantly produced in initial hard partonic scattering processes in the...
Using the chromo-electric dipole coupling Hamiltonian from QCD multipole expansion, we derive the dissociation cross sections of heavy quarkonia by thermal gluons at next-to-leading order (NLO, also known as inelastic parton scattering dissociation) in the Quark-Gluon Plasma (QGP) in the framework of second order quantum mechanical perturbation theory. While suffering divergence (infrared and...
Results on quarkonium production in p-Pb collisions from LHC run-1 and run-2 have now reached a considerable accuracy and represent, together with RHIC findings, an important tool for the study of cold nuclear matter effects. While for strongly bound states those effects are probably dominated by nuclear shadowing, excited quarkonium states have been shown to be affected by additional...
LHCb is one of the four large experiments at the LHC. It has taken ion-ion collisions and dedicated fixed-target data samples for the first time in 2015. In this contribution, we will discuss not yet exploited experimental possibilities for this forward acceptance detector both in the correlation as well as in the heavy-flavour sector. The goal is to trigger an open discussion on new ideas...
It has been proposed that the azimuthal distributions of heavy flavor quark-antiquark pairs may be modified in the medium of a heavy-ion collision. This assumption is tested through next-to-leading order (NLO) calculations of the azimuthal distribution, $d\sigma/d\phi$, including transverse momentum broadening, employing $\langle k_T^2 \rangle$ and fragmentation in exclusive $Q \overline Q$...
By extracting the beam with a bent crystal or by using an internal gas target, the multi-TeV proton and lead LHC beams allow one to perform the most energetic fixed-target experiments ever and to study pp, pd and pA collisions at sqrt(sNN)=115 GeV and Pbp and PbA collisions at sqrt(sNN)=72 GeV with high precision and modern detection techniques. A broad programme, covering the large-x frontier...
We present recent computations of loop functions in thermal QCD like the Polyakov loop, correlators of Polyakov loops and Wilson lines, and the cyclic Wilson loop. We discuss divergences and how to renormalize them. Finally we compare with lattice data.
Assuming full screening of quarkonia in QGP as well as full thermalization of charm quarks in QGP, quarkonium production in the Statistical Hadronization Model occurs at chemical freeze-out (which, for high energies, likely coincides with the QCD phase boundary). The model describes very well the LHC J/psi data on centrality, transverse momentum and rapidity dependence and gives definite...
Heavy-flavor particles are believed to be versatile probes of the medium produced in high-energy nuclear collisions. Their masses provide a large scale which implies several benefits in the theoretical and phenomenological analysis of their vacuum and in-medium properties. We discuss a selfconsistent many-body approach that allows for a comprehensive description of both bound and scattering...
I will review recent progress in studying the in-medium properties of open heavy flavor mesons and quarkonia from lattice QCD. I will report on recent results on in-medium spectral functions for bottomonia and charmonia from non-relativistic
QCD (NRQCD). Discuss new results on the determination of the complex heavy quark potential on the lattice. Furthermore, I will show results on spatial...
Baryons with various strange content are studied across the deconfinement transition using our Nf=2+1 flavour anisotropic FASTSUM lattices. Below Tc we find that the positive-parity states are largely temperature independent, whereas the negative-parity hadron masses decrease as Tc is approached. Near, and above Tc, the parity partners' masses converge, with parity doubling being closest for...
We calculate the (semi-)static hard-loop self-energy and propagator using the Keldysh formalism in a momentum-space anisotropic quark-gluon plasma. The static retarded, advanced, and Feynman (symmetric) self-energies and propagators are calculated to all orders in the momentum-space anisotropy parameter ξ. For the retarded and advanced self-energies/propagators, we present a concise derivation...
Heavy quarkonium related observables are very useful to obtain information about the medium created in relativistic heavy ion collisions. In recent years the theoretical description of quarkonium in a medium has moved towards a more dynamical picture in which decay and recombination processes are very important. In this talk we will discuss the equations that describe the evolution of the...
Both collision geometry and event-by-event fluctuations are encoded in the experimentally observed flow harmonic distribution $p(v_n)$ and 2k-particle cumulants $c_n\{2k\}$. In the present talk, we systematically connect these observables to each other by employing Gram-Charlier A series. Also we quantify the deviation of the flow harmonic distribution from Bessel-Gaussianity in terms of the...
I present the state-of-the-art of anisotropic flow fluctuations in heavy-ion collisions. Event-by-event fluctuations of flow coefficients are investigated experimentally by means of multi-particle cumulants, which are indicators of the non-Gaussian behavior of the $v_n$ distributions. After a brief review of the theoretical basis underlying cumulants and the related observables, I use selected...
I will discuss the LHC heavy flavor data in pA collisions to constrain the gluon density at low x in nuclei, where no other data exist. Our results show strong gluon shadowing at low x compared to proton PDF and significant reduction of the current (underestimated) nPDF errors. Its implications for the heavy-ion physics will also be discussed.
Symmetric cumulants, the novel flow observables which quantify the correlations between event-by-event fluctuations of two different flow harmonics, have been utilized extensively by the experimentalists in recent flow analyses in ultra-relativistic nuclear collisions, both at RHIC and LHC.
These observables provide the strong constraints for the details of QGP's temperature dependence of...
We show that far-from-equilibrium relativistic fluid dynamics may be systematically defined, for arbitrary flow profiles, in terms of a generalized tensorial expansion with transport coefficients that contain an all order resummation in gradients. In this formulation, the transport coefficients of far-from-equilibrium fluid dynamics depend not only on the microscopic properties of the system...
We study the propagation of charm and bottom quarks in the quark-gluon plasma (QGP) by means of a relativistic Boltzmann transport approach. The non-perturbative interaction of heavy quarks is described by means of a quasi-particle approach that entails only a weak dependence of the drag on the temperature. This features, along with hadronization by coalescence, plays a fundamental role to...
