The Deconfinement Phase Transition in One-Flavour QCD

For the exploration of the phase diagram of QCD, effective Polyakov loop theories derived from lattice QCD provide a valuable tool in the heavy quark mass regime. In practice, the evaluation of these theories is complicated by the appearance of long-range and multipoint interaction terms. On the other hand, it is well known that for theories with such kind of interactions mean field approximations can be expected to yield reliable results. Here, we apply this framework to the...

We determine the location of the critical point where the first-order deconfining transition in the heavy-quark region turns into a crossover in finite-temperature and density lattice QCD with 2+1 flavors of Wilson quarks. Combining a hopping parameter expansion (HPE) of the quark determinant with a reweighting method, we evaluate the chemical potential dependence of the critical point. By systematically calculating the coefficients of the hopping parameter expansion up to a ...

We describe how the general mechanism of partial deconfinement applies to large-$N$ QCD and the partially-deconfined phase inevitably appears between completely-confined and completely-deconfined phases. Furthermore, we propose how the partial deconfinement can be observed in the real-world QCD with SU(3) gauge group. We propose the relationship between the behaviors of the Polyakov loop and other quantities. We test our proposal against lattice simulation data and find a non...

Lattice simulations have demonstrated that a background (electro)magnetic field reduces the chiral/deconfinement transition temperature of quantum chromodynamics for eB < 1 GeV^2. On the level of observables, this reduction manifests itself in an enhancement of the Polyakov loop and in a suppression of the light quark condensates (inverse magnetic catalysis) in the transition region. In this paper, we report on lattice simulations of 1+1+1-flavor QCD at an unprecedentedly hig...

We calculate the deconfinement line of transitions for large Nc QCD at finite temperature and chemical potential in two different regimes: weak coupling in the continuum, and, strong coupling on the lattice, working in the limit where Nf is of order Nc. In the first regime we extend previous weak-coupling results from one-loop perturbation theory on S^1 x S^3 to higher temperatures, where the theory reduces to a matrix model, analogous to that of Gross, Witten, and Wadia. We ...

We analyze the dependence of the QCD transition temperature on the quark (or pion) mass. We find that a linear sigma model, which links the transition to chiral symmetry restoration, predicts a much stronger dependence of T_c on m_pi than seen in present lattice data for m_pi >~ 0.4 GeV. On the other hand, working down from m_pi=infinity, an effective Lagrangian for the Polyakov loop requires only small explicit symmetry breaking, b_1 ~ exp(-m_pi), to describe T_c(m_pi) in th...

This is a review of strong coupling approaches to grasp the nature of the phase transition in finite temperature and density QCD. We commence with classics of the center symmetry and the Polyakov loop in pure gauge theories. The effective action derived in the strong coupling limit gives qualitatively plausible behavior for the deconfinement transition at finite temperature. We can apply the strong coupling analysis to describe the chiral phase transition with the help of lar...

We extend our previous study of the QCD phase structure in the heavy quark region to non-zero chemical potentials. To identify the critical point where the first order deconfining transition terminates, we study an effective potential defined by the probability distribution function of the plaquette and the Polyakov loop. The reweighting technique is shown to be powerful in evaluating the effective potential in a wide range of the plaquette and Polyakov loop expectation value...

In this paper we study the confinement/deconfinement transition in lattice $SU(2)$ QCD at finite quark density and zero temperature. The simulations are performed on an $32^4$ lattice with rooted staggered fermions at a lattice spacing $a = 0.044 \mathrm{~fm}$. This small lattice spacing allowed us to reach very large baryon density (up to quark chemical potential $\mu_q > 2000 \mathrm{~MeV}$) avoiding strong lattice artifacts. In the region $\mu_q\sim 1000 \mathrm{~MeV}$ we ...

It is well established that physical quantities like the heavy quark potentials get temperature independent at sufficiently short distances. As a first application of this feature we suggest a new order parameter for the confinement/deconfinement phase transition. Our investigations are based on recent lattice studies.