<p>We study the effect of finite spin quark density on the chiral and deconfinement thermal crossovers using numerical simulations of lattice QCD with two dynamical light quarks. The finite spin density is introduced by the quark spin potential in the canonical formulation of the spin operator. We show that both chiral and deconfinement temperatures are decreasing functions of the spin potential. We determine the parabolic curvatures of crossover temperatures in a limit of physical quark masses.</p>

JINR

V.V. Braguta

France

Romania

M.N. Chernodub

A.A. Roenko

Chiral and deconfinement thermal transitions at finite quark spin polarization in lattice QCD simulations

<p>We study the properties of gluon plasma subjected to a weak acceleration using first-principles numerical Monte Carlo simulations. We use the Luttinger (Tolman-Ehrenfest) correspondence between temperature gradient and gravitational field to impose acceleration in imaginary time formalism. Under acceleration, the system resides in global thermal equilibrium. Our results indicate that even the weakest acceleration up to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>a</mi><mo>≃</mo><mn>16</mn><mtext> </mtext><mtext> </mtext><mi>MeV</mi></mrow></math> drastically softens the deconfinement phase transition, converting the first-order phase transition of a static system to a soft crossover for accelerating gluons. The accelerating environment can be relevant to the first moments of the early Universe and the initial glasma regime of relativistic heavy ion collisions. In particular, our results imply that the acceleration, if present, may also inhibit the detection of the thermodynamic phase transition from quark-gluon plasma to the hadronic phase.</p>

Russia

V.A. Goy

China

A.V. Molochkov

D.V. Stepanov

A.S. Pochinok

Extreme Softening of QCD Phase Transition under Weak Acceleration: First-Principles Monte Carlo Results for Gluon Plasma

The conformal anomaly in curved spacetime generates a nontrivial anomalous vertex, given by the three-point correlation function TTT of the energy-momentum tensor <math><msup><mrow><mi>T</mi></mrow><mrow><mi>μ</mi><mi>ν</mi></mrow></msup></math>. We show that a temperature inhomogeneity in a gas of charged massless particles generates, via the TTT vertex, a pressure anisotropy with respect to the axis of the temperature variation. This very particular signature may provide an experimental access to the elusive gravitational coefficient b which determines the anomaly contribution of the Weyl tensor to the trace of the energy-momentum tensor in curved spacetime. We present an estimate of the pressure anisotropy both for fermionic quasiparticles in the solid-state environment of Dirac semimetals as well as for a quark-gluon plasma in relativistic heavy-ion collisions. In both cases, the pressure anisotropy is small compared to the mean thermal pressure.

Italy

Claudio Corianò

Matteo Maria Maglio

Anomalous gravitational TTT vertex, temperature inhomogeneity, and pressure anisotropy

Quantum polarization effects associated with the conformal anomaly in a static magnetic field background may generate a transverse electric current in the vacuum. The current may be produced either in an unbounded curved spacetime or in a flat spacetime in a physically bounded system. In both cases, the magnitude of the electric current is proportional to the beta-function associated with renormalization of the electric charge. In our article, we investigate the electric current density induced by the magnetic field in the vicinity of a Dirichlet boundary in the scalar QED. Using first-principle lattice simulations we show that the electric current, generated by this “conformal magnetic effect at the edge” (CMEE), is well described by the conformal anomaly provided the conformal symmetry is classically unbroken. Outside of the conformal limit, the current density is characterized by an anomalous power law near the edge of the system and by an exponential suppression of the current far away from the edge.

Conformal magnetic effect at the edge: A numerical study in scalar QED

We argue that in the Copenhagen (“spaghetti”) picture of the QCD vacuum the chromomagnetic flux tubes exhibit chromoelectric superconductivity. We show that the superconducting chromoelectric currents in the tubes may be induced by the topological charge density.