Conveners
QCD at nonzero Temperature and Density: Session 4-1 B
- Shinji Ejiri (Niigata University)
QCD at nonzero Temperature and Density: Session 4-2 A
- Gert Aarts (Swansea University)
QCD at nonzero Temperature and Density: Session 5-1 C
- Jun Nishimura (KEK)
QCD at nonzero Temperature and Density: Session 6-1 C
- Heng-Tong Ding (Central China Normal University)
QCD at nonzero Temperature and Density: Session 7-2 C
- Waseem Kamleh (University of Adelaide)
The thermal transition in QCD has been studied in detail using the staggered-quark formulation. Here we report on progress using Nf=2+1 flavours of Wilson fermions, employing anisotropic, fixed-scale lattice simulations. Observables are compared for two values of the pion mass, focusing on chiral properties: the chiral condensate and its susceptibility, quark number susceptibilities, and the...
We present a lattice QCD based determination of the chiral phase transition temperature in QCD with two massless (up and down) and one strange quark having its physical mass. We propose and calculate two novel estimators for the chiral transition temperature for several values of the light quark masses, corresponding to Goldstone pion masses in the range between (approximately) 58 MeV and...
We will present results on the Dirac eigenvalue spectrum as well as its relation to the axial U(1) and SU(2)xSU(2) symmetries at a high temperature in (2+1)-flavor QCD. The simulations are carried out using the highly improved staggered quarks (HISQ) action on Nτ = 8, 12 and 16 lattices with the aspect ratio Nσ /Nτ in a range of [4,9] and 4-5 pion masses ranging from 160 MeV to 55 MeV at a...
We propose new way of heavy ion collisions experiment data analysis. We analyze physical parameters of fireball created in RHIC experiment based on Grand Canonical Distribution and different Lattice QCD data available at the moment. Our results on chemical potential are in agreement with previous model estimations and do not depend on Lattice setup. At same time, we found possible T(V) states...
The chiral symmetry restoration of QCD, with two light flavours in the chiral limit, is expected to be a phase transition belonging to the universality class of 3d O(N) models. The imprint of the criticality should be observed in the thermodynamic observables if we move close enough to the chiral limit. We discuss results of conserved charge fluctuations and Polyakov loop, which we propose to...
Hadronic matter is known to change its behaviour during a crossover at finite temperature. One part of this crossover is the chiral transition, whose properties are well studied. The other part involves the fate of hadronic bound states and single quarks, the transition of which is less clear. We study two-flavor QCD for temperatures starting from 190 MeV and quark masses down to...
We will present results on the second order fluctuations of net baryon number, electric charge and strangeness as well as correlations among these conserved charges in (2+1)-flavor lattice QCD in the presence of a background magnetic field.
Simulations are performed using the tree level improved gauge action and the highly improved staggered quark
(HISQ) action with a fixed scale approach...
We study the pressure anisotropy in anisotropic finite-size systems in SU(3) Yang-Mills theory at nonzero temperature. Lattice simulations are performed on lattices with anisotropic spatial volumes with periodic boundary conditions. The energy-momentum tensor defined through the gradient flow is used for the analysis of the stress tensor on the lattice. We find that a clear finite-size effect...
In this report we present our first results on lattice study of QCD equation of state in external magnetic field and at finite baryon density. The simulations are performed with $N_f = 2+1$ rooted staggered quarks at physical quark masses. Finite baryon density is implemented through the lattice simulations at imaginary chemical potential. The results for the equation of state are expanded in...
The chiral susceptibility, or the first derivative of the chiral condensate, is used as a probe for QCD phase transition. It is well-known that the chiral condensate is an order parameter of SU(2)_L x SU(2)_R symmetry breaking. However, the condensate also breaks the axial U(1) symmetry, which is usually not paid attention as it is already broken by anomaly. In this talk, we would like to show...
We present an update on our previous studies [1] of pure U(1) lattice gauge theory with a sign problem due to a complex coupling \beta. To that end a novel simulation method is employed:
Configuration space is rewritten as a union of linear submanifolds in complexified space. These submanifolds are the tangent spaces of the Lefschetz thimble decomposition. Therefore the sign problem is...
Monte Carlo simulation of gauge theories with a theta term is known to be extremely difficult due to the sign problem. We consider the complex Langevin method (CLM), which is one of the approaches to overcome this problem. As a first step, we apply the method to 2D U(1) gauge theory with a theta term, which can be solved analytically. We find that naive implementation of the method fails...
The Monte Carlo simulation of the gauge theory with a theta term is difficult due to the sign problem. We use the complex Langevin method to overcome the problem. In our previous work on two-dimensional U(1) gauge theory with a theta term, we were able to reproduce the exact solution by introducing a puncture on the torus. We also proved that the effect of the puncture disappears in the...
We explore the phase diagram of the 2+1-dimensional Gross-Neveu model in the limit of infinite flavors, which shares certain properties with QCD, and the existence of an inhomogeneous phase using lattice field theory. Numerical results are presented, which include the phase boundaries in the $\mu$-$T$ plane as well as the structure of the chiral condensate in the inhomogeneous phase.
We provide evidence for partial deconfinement by using lattice Monte Carlo simulations of some bosonic matrix models.
Partial deconfinement is the phenomenon that coexists the confined and deconfined phases in the system, in particular of several large-N gauge theories, at finite temperature.
By appropriately fixing the gauge, we observe that only submatrices deconfine in the analysis of the...
We show the heavy quark diffusion coefficient calculated on the lattice. The coefficient is obtained from the color-electric correlators via Kubo formula. The correlators are measured at 1.5$T_c$ on different large isotropic lattices in the quenched approximation under gradient flow. After continuum extrapolation we also extrapolate the continuum correlators back to zero flow time. The...
We present results of chiral condensates, masses and decay constants of neutral pseudo scalar mesons in (2+1)-flavor QCD in the presence of external magnetic fields at zero temperature. We discuss the validity of Gell-Mann-Oakes-Renner relation in a wide region of magnetic field strength $eB$ up to around 3.5 GeV$^2$. The simulations were performed on $32^3\times96$ lattices using the Highly...
We report on our recent results of the shear viscosity $\eta$ of the classical Yang-Mills (CYM) field on a lattice by using the Green-Kubo formula, where the shear viscosity is calculated from the time-correlation function of the energy-momentum tensor in equilibrium. The point of our investigation consists in utilization of the inherent scale invariance of CYM, and thereby the possible...
We propose the sparse modeling method to estimate the spectral function from the smeared correlation functions. We give a description of how to obtain the shear viscosity from the correlation function of the renormalized energy-momentum tensor (EMT) measured by the gradient flow method (C(t,τ)) for the quenched QCD at finite temperature. The measurement of the renormalized EMT in the gradient...
In this report we present the results of lattice study of how rotation influences confinement/deconfinement transition in SU(3) gluodynamics. To conduct this study we pass to the reference frame which rotates with the system under consideration. In this reference frame rotation is accounted for by the external gravitational field. We calculate the Polyakov loop, its susceptibility
and...
The phase structure of QCD at finite density is expected to be revealed by the complex Langevin method (CLM), which is a promising approach to overcome the sign problem. In particular, we discuss the possibility of investigating the color superconductivity (CSC) on the lattice by the CLM. Towards that end, we predict the parameter region in which CSC occurs in lattice perturbation theory based...
In a recent work we investigated the existence of inhomogeneous chiral phases (i.e., a phase where the chiral condensate has a spatial dependence) in the 1+1-dimensional Gross-Neveu model at finite number of fermion flavors. In the present work we continue this investigation by studying the formation of baryons, their spatial distribution and their relation to the inhomogeneous chiral condensate.
Replica evolution of classical field is proposed as an approximate simulator of real-time quantum field dynamics at finite temperatures. We consider $N$ classical field configurations $(\phi_{\tx},\pi_{\tx} (\tau=0,1,\cdots N-1)$, dubbed as replicas, which interact with each other via the $\tau$-derivative terms and evolve with the classical equation of motion. The $\tau$-derivative terms in...
