QCD equations of state and speed of sound in neutron stars

T Kojo - AAPPS Bulletin, 2021 - Springer
Neutron stars are cosmic laboratories to study dense matter in quantum chromodynamics
(QCD). The observable mass-radius relations of neutron stars are determined by QCD …

A window on infrared QCD with small expansion parameters

M Peláez, U Reinosa, J Serreau… - Reports on Progress …, 2021 - iopscience.iop.org
Lattice simulations of the QCD correlation functions in the Landau gauge have established
two remarkable facts. First, the coupling constant in the gauge sector—defined, eg, in the …

Implications of NICER for neutron star matter: The QHC21 equation of state

T Kojo, G Baym, T Hatsuda - The Astrophysical Journal, 2022 - iopscience.iop.org
The recent NICER measurement of the radius of the neutron star PSR J0740+ 6620, and the
inferred small variation of radii from 1.4 to 2.1 M⊙, reveal key features of the equation of …

Stiffening of matter in quark-hadron continuity

T Kojo - Physical Review D, 2021 - APS
We discuss stiffening of matter in quark-hadron continuity. We introduce a model that relates
quark wave functions in a baryon and the occupation probability of states for baryons and …

Equation of state for hot QCD and compact stars from a mean-field approach

A Motornenko, J Steinheimer, V Vovchenko… - Physical Review C, 2020 - APS
The thermodynamic properties of high temperature and high density QCD matter are
explored within the chiral SU (3)-flavor parity-doublet Polyakov-loop quark-hadron mean …

Peaks of sound velocity in two color dense QCD: Quark saturation effects and semishort range correlations

T Kojo, D Suenaga - Physical Review D, 2022 - APS
We discuss stiffening of dense matter in two color QCD (QC 2 D) where hadrons are mesons
and diquark baryons. We study two models which describe a transition of matter from the …

Chiral restoration of nucleons in neutron star matter: Studies based on a parity doublet model

T Minamikawa, B Gao, T Kojo, M Harada - Symmetry, 2023 - mdpi.com
We review the chiral variant and invariant components of nucleon masses and the
consequence of their existence on the chiral restoration in extreme conditions, particularly in …

Quark-hadron crossover equations of state for neutron stars: Constraining the chiral invariant mass in a parity doublet model

T Minamikawa, T Kojo, M Harada - Physical Review C, 2021 - APS
We construct an equation of state (EOS) for neutron stars by interpolating hadronic EOS at
low density and quark EOS at high density. A hadronic model based on the parity doublet …

Remarks on nuclear matter: How an condensate can spike the speed of sound, and a model of baryons

RD Pisarski - Physical Review D, 2021 - APS
I make two comments about nuclear matter. First, I consider the effects of a coupling
between the O (4) chiral field, ϕ→, and the ω μ meson,∼+ ϕ→ 2 ω μ 2; for any net baryon …

Nonperturbative quark matter equations of state with vector interactions

K Otto, M Oertel, BJ Schaefer - The European Physical Journal Special …, 2020 - Springer
Nonperturbative equations of state (EoSs) for two and three quark flavors are constructed
with the functional renormalization group (FRG) within a quark-meson model truncation …