We establish the existence of a far-from-equilibrium attractor in weakly-coupled gauge theory undergoing one-dimensional Bjorken expansion. We demonstrate that the resulting far-from-equilibrium evolution is insensitive to certain features of the initial condition, including both the initial momentum-space anisotropy and initial occupancy. We find that this insensitivity extends beyond the...
Motivated by the quark-gluon plasma, we develop a simulation method to obtain the spectral function of (Wilson) fermions non-perturbatively in a non-Abelian gauge theory with large gluon occupation numbers. We apply our method to a non-Abelian plasma close to its non-thermal fixed point, i.e., in a far-from-equilibrium self-similar regime, and find mostly very good agreement with perturbative...
The evolution of a heavy ion collision passes close to the O(4) critical point of QCD, where fluctuations of the order parameter are expected to be enhanced. Using the appropriate stochastic hydrodynamic equations in mean field close to the
near the pseudo-critical point, we compute how these enhanced fluctuations modify the transport coefficients of QCD and make a phenomenological estimate...
Using non-relativistic QCD techniques on finite temperature lattice configurations, we will present results pertaining to the fate of the Bottom and anti-Bottom quarkonium states of Υ(1S), Υ(2S) and Υ(3S) in Quark-Gluon-Plasma (QGP). We will present results on how the mass and spectral width of these states change with temperature. We will also show new results on how the finite temperature...
We study the transitions between the different color states of a static
quark-antiquark pair, singlet and octet, in a thermal medium. This
is done non-perturbatively exploiting the infinite mass limit of QCD. This study is interesting because it can be used
for future developments within the framework of Effective Field Theories
(EFTs) and because it can be combined with other techniques,...
We present a comparison among various methods used to extract the spectral functions of S- and P-wave meson states from non-zero temperature NRQCD correlation functions using the FASTSUM anisotropic lattice: the maximum likelihood, Backus Gilbert, and machine learning approaches. We review the common features that can be extracted by all methods and compare the results for masses and widths.
In this talk I will review the recent developments on the phenomenology and experimental searches for collectivity in small collision systems. For the phenomenology part I will focus on the hybrid approach based on the Color Glass Condensate (CGC) and Hydrodynamics (hydro) simulation [1]. For the experimental part my focus will be on the RHIC small system scan program [2]. I will discuss how...
Hadron production measurement in small collision systems (such as p+Al, p+Au, d+Au, $^3$He+Au) may allow to explore the minimal conditions for the quark-gluon plasma formation. Such research has become particularly crucial with the observation of the light hadrons collective behavior in small collision systems. Among the large variety of light hadrons, φ-meson is of particular interest...
Precise knowledge of the thermodynamic properties of zero-temperature, high-density quark matter (QM) can constrain the neutron-star-matter equation of state (EOS), even at much lower densities. However, current bounds on this QM EOS suffer from rather large uncertainties stemming from renormalization-scale dependence. In this talk, I will lay out how to improve the dense QM EOS beyond N2LO,...
We investigate the thermal QCD phase transition and its scaling properties on the lattice. The simulations are performed with N_f=2+1+1 Wilson twisted mass fermions at pion masses from physical up to heavy quark regime. We introduce a new chiral order parameter, which is free from linear mass contributions and turns out to be useful for the study of scaling behaviour. Our results are...
In addition to the well known-sign problem, methods currently used to study finite baryon density lattice QCD suffer from additional uncontrolled systematics, coming e.g. from the analytic continuation problem one faces with the Taylor or imaginary chemical potential methods. We formulate and test a new method - sign reweighting - that works directly at finite chemical potential and is free...
I will give a brief review on the theory of jet quenching and discuss some recent progress toward measuring quark and gluon jet modification in heavy-ion collisions.
The interaction of a jet with the medium created in heavy-ion collisions is not yet fully understood from a QCD-perspective. This is mainly due to the nonperturbative nature of this interaction which affects both, transverse jet momentum broadening and jet quenching.
We review how lattice simulations of Electrostatic QCD can be properly extrapolated to the continuum, which operators to...
In this talk, I will report on our numerical lattice simulations of partons traversing the boost-invariant, non-perturbative glasma as created at the early stages of collisions at RHIC and LHC [1]. Since these highly energetic partons are produced from hard scatterings during heavy ion collisions, they are already affected by the first stage of the medium's time evolution, the glasma, which is...
NA61/SHINE (SPS Heavy Ion and Neutrino Experiment) is a fixed-target experiment operating at the CERN SPS accelerator. The main goal of the strong interactions program of NA61/SHINE is to study the properties of the phase transition between confined matter and quark-gluon plasma by performing a two-dimensional scan in beam momentum and size of collided nuclei. Within this program, collisions...
We discuss the behaviour of a universal combination of susceptibility and correlation length in the Ising model in two and three dimensions, in presence of both magnetic and thermal perturbations, in the neighbourhood of the critical point. In three dimensions we address the problem using a parametric representation of the equation of state. In two dimensions we make use of the exact...
In relativistic nuclear collisions the production of hadrons with light (u,d,s) quarks is quantitatively described in the framework of the Statistical Hadronization Model (SHM). Since charm quarks are dominantly produced in initial hard collisions but interact strongly in the hot fireball, charmed hadrons can be incorporated into the SHM by treating charm quarks as 'impurities' with thermal...
We solve the Lindblad equation describing the Brownian motion of a Coulombic heavy quark-antiquark pair in a strongly coupled quark-gluon plasma using the highly efficient Monte Carlo wave-function method. The Lindblad equation has been derived in the framework of pNRQCD and fully accounts for the quantum and non-Abelian nature of the system. The hydrodynamics of the plasma is realistically...
Since the first positive measurement of the Λ-hyperon global spin polarization in heavy-ion collisions by STAR in 2017, the understanding of the nature of this phenomenon is one of the most intriguing challenges for the community. As relativistic fluid dynamics celebrates multiple successes in describing collective dynamics of the QCD matter in such reactions, the natural question arises...
Experimental measurements of multiplicity fluctuations are used to extract information about the properties of the quark-gluon plasma and transition to the hadron gas phase in heavy-ion collisions. In particular, the event-by-event fluctuations of conserved quantities within a fixed rapidity range can be related to thermodynamic properties of the medium, allowing for direct comparison to...
The spinodal instability is a prime signal for the first-order phase transition with negative speed of sound squared $cs^2$ in the Quantum-ChromoDynamics phase diagram relevant for the RHIC energy scan. In recent studies [1,2], one evolves planar unstable black branes dual to a plasma with a first order phase transition subject to the spinodal instability. Near a critical...
We will discuss thermal modifications of charmonium and bottomonium spectral properties in a hot gluonic medium from continuum extrapolated lattice results. The dissociation temperatures of quarkonia as well as charm and bottom quark diffusion coefficients are presented in the temperature region from 1.1$T_c$ to 2.25$T_c$ in the quenched approximation with valence quarks tuned to physical...
In recent years, a significant theoretical effort has been made towards a dynamical description of quarkonia inside the Quark-Gluon Plasma (QGP), using the open quantum systems formalism. In this framework, one can get a real-time description of a quantum system (here the quarkonium) in interaction with a thermal bath (the QGP) by integrating out the bath degrees of freedom and studying the...
