TY - JOUR

T1 - Phenomenological QCD equation of state for massive neutron stars

AU - Kojo, Toru

AU - Powell, Philip D.

AU - Song, Yifan

AU - Baym, Gordon

N1 - Publisher Copyright:
© 2015 American Physical Society.

PY - 2015/2/3

Y1 - 2015/2/3

N2 - We construct an equation of state for massive neutron stars based on quantum chromodynamics phenomenology. Our primary purpose is to delineate the relevant ingredients of equations of state that simultaneously have the required stiffness and satisfy constraints from thermodynamics and causality. These ingredients are (i) a repulsive density-density interaction, universal for all flavors, (ii) the color-magnetic interaction active from low to high densities, (iii) confining effects, which become increasingly important as the baryon density decreases, and (iv) nonperturbative gluons, which are not very sensitive to changes of the quark density. We use the following "3-window" description: At baryon densities below about twice normal nuclear density, 2n0, we use the Akmal-Pandharipande-Ravenhall (APR) equation of state, and at high densities, ≥(4-7)n0, we use the three-flavor Nambu-Jona-Lasinio (NJL) model supplemented by vector and diquark interactions. In the transition density region, we smoothly interpolate the hadronic and quark equations of state in the chemical potential-pressure plane. Requiring that the equation of state approach APR at low densities, we find that the quark pressure in nonconfining models can be larger than the hadronic pressure, unlike in conventional equations of state. We show that consistent equations of state of stiffness sufficient to allow massive neutron stars are reasonably tightly constrained, suggesting that gluon dynamics remains nonperturbative even at baryon densities ∼10n0.

AB - We construct an equation of state for massive neutron stars based on quantum chromodynamics phenomenology. Our primary purpose is to delineate the relevant ingredients of equations of state that simultaneously have the required stiffness and satisfy constraints from thermodynamics and causality. These ingredients are (i) a repulsive density-density interaction, universal for all flavors, (ii) the color-magnetic interaction active from low to high densities, (iii) confining effects, which become increasingly important as the baryon density decreases, and (iv) nonperturbative gluons, which are not very sensitive to changes of the quark density. We use the following "3-window" description: At baryon densities below about twice normal nuclear density, 2n0, we use the Akmal-Pandharipande-Ravenhall (APR) equation of state, and at high densities, ≥(4-7)n0, we use the three-flavor Nambu-Jona-Lasinio (NJL) model supplemented by vector and diquark interactions. In the transition density region, we smoothly interpolate the hadronic and quark equations of state in the chemical potential-pressure plane. Requiring that the equation of state approach APR at low densities, we find that the quark pressure in nonconfining models can be larger than the hadronic pressure, unlike in conventional equations of state. We show that consistent equations of state of stiffness sufficient to allow massive neutron stars are reasonably tightly constrained, suggesting that gluon dynamics remains nonperturbative even at baryon densities ∼10n0.

UR - http://www.scopus.com/inward/record.url?scp=84922365884&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84922365884&partnerID=8YFLogxK

U2 - 10.1103/PhysRevD.91.045003

DO - 10.1103/PhysRevD.91.045003

M3 - Article

AN - SCOPUS:84922365884

SN - 1550-7998

VL - 91

JO - Physical Review D - Particles, Fields, Gravitation and Cosmology

JF - Physical Review D - Particles, Fields, Gravitation and Cosmology

IS - 4

M1 - 045003

ER -