Thermal effects on sound velocity peak and conformality in isospin QCD

Abstract

We study thermal effects on equations of state (EOS) in isospin QCD, utilizing a quark-meson model coupled to a Polyakov loop. The quark-meson model is analyzed at one-loop that is the minimal order to include quark substructure constraints on pions which condense at finite isospin density. In the previous study we showed that the quark-meson model at zero temperature produces the sound velocity peak and the negative trace anomaly in the domain between the chiral effective theory regime at low density and the perturbative QCD regime at high density, in reasonable agreement with lattice simulations. We now include thermal effects from quarks in the Polyakov loop background and examine EOS, especially the sound velocity and trace anomaly along isentropic trajectories. At large isospin density, there are three temperature windows; (i) the pion condensed region with almost vanishing Polyakov loops, (ii) the pion condensed region with finite Polyakov loops, and (iii) the quark gas without pion condensates. In the domain (i), the gap associated with the pion condensate strongly quenches thermal excitations. As the system approaches the domain (ii), thermal quarks, which behave as non-relativistic particles, add energy density but little pressure, substantially reducing the sound velocity to the value less than the conformal value while increasing the trace anomaly toward the positive value. Approaching the domain (iii), thermal quarks become more relativistic as pion condensates melt, increasing sound velocity toward the conformal limit. Corrections from thermal pions are also briefly discussed.

12 pages, 8 figures

References in corpus (32)

• GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral
• Shapiro delay measurement of a two solar mass neutron star
• A Massive Pulsar in a Compact Relativistic Binary
• A NICER View of the Massive Pulsar PSR J0740+6620 Informed by Radio Timing and XMM-Newton Spectroscopy
• Refined Mass and Geometric Measurements of the High-Mass PSR J0740+6620
• The Phase Structure of the Polyakov--Quark-Meson Model
• Nuclear equation of state for core-collapse supernova simulations with realistic nuclear forces
• Dense Nuclear Matter Equation of State from Heavy-Ion Collisions
• Phenomenological QCD equation of state for massive neutron stars
• The chiral and deconfinement crossover transitions: PNJL model beyond mean field
• Trace anomaly as signature of conformality in neutron stars
• Merger and post-merger of binary neutron stars with a quark-hadron crossover equation of state
• Implications of NICER for neutron star matter: the QHC21 equation of state
• Equation of state and speed of sound of isospin-asymmetric QCD on the lattice
• Gravitational Wave Signal for Quark Matter with Realistic Phase Transition
• Stiffening of matter in quark-hadron continuity
• Momentum Shell in Quarkyonic Matter from Explicit Duality: A Dual Model for Cold, Dense QCD
• QCD Equation of State of Dense Nuclear Matter from a Bayesian Analysis of Heavy-Ion Collision Data
• Peaks of sound velocity in two color dense QCD: quark saturation effects and semishort range correlations
• Large and massive neutron stars: Implications for the sound speed in dense QCD
• Electromagnetic charge radius of the pion at high precision
• Compiled Properties of Nucleonic Matter and Nuclear and Neutron Star Models from Non-Relativistic and Relativistic Interactions
• Sound velocity peak and conformality in isospin QCD
• Binary neutron star mergers as a probe of quark-hadron crossover equations of state
• Insights on the peak in the speed of sound of ultradense matter
• Exploring thermal effects of the hadron-quark matter transition in neutron star mergers
• Structure in the speed of sound: from neutron stars to heavy-ion collisions
• On-shell parameter fixing in the quark-meson model
• Color screening in cold quark matter
• Probing the hadron mass spectrum in dense two-color QCD with the linear sigma model
• Sound velocity peak induced by the chiral partner in dense two-color QCD
• On the effective lagrangian at nonzero isospin chemical potential

Cited by in corpus (4)

• Speed of sound peak in isospin QCD: a natural prediction of the Medium Separation Scheme
• Density dependent speed of sound and its consequences in neutron stars
• Roles of $U(1)$ axial anomaly effects in cold and dense two-color QCD with $2+2$ flavors
• Thermal quarks and Polyakov loops in two-color dense QCD