A consistent description of neutron stars with quark cores

Vikram Soni,Dipankar Bhattacharya

doi:10.1016/j.physletb.2006.10.001

Vikram Soni, Dipankar Bhattacharya

Open Access

https://doi.org/10.1016/j.physletb.2006.10.001

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Abstract

We consider the equation of state of hadroninc and quark matter at finite density in mean field theory, through an effective chiral Lagrangian whose parameters (coupling constants) are all fixed by hadronic data. Between three to seven times nuclear density, for charge neutral quark matter in β equilibrium, we find the ground state to be a neutral pion condensate. With increasing baryon density we then expect nuclear matter, followed by pion condensed quark matter at intermediate density, and finally the diquark colour-flavour CFL condensate. These are all states with chiral spontaneous symmetry breaking (SSB). We find another remarkable feature and this is that the scalar (pseudoscalar) coupling, λ , has a crucial and unexpected influence on the physics of neutron stars. Neutron stars with pion condensed quark matter cores exist only in a small window, between, 5.7 < λ < 6.45 . Interestingly, this range is consistent with the value of λ derived from π , π scattering data and such stellar cores may carry magnetar strength magnetic fields.

Highlights

Neutron stars have been a subject of abiding interest for several decades
THE GROUND STATE FOR 3 FLAVOUR QUARK MATTER. For neutron stars it is the ground state of charge neutral quark matter in β equilibrium at given density that is needed for the equation of state
A. quark matter ground states (i) At issue is the question if the neutral pion condensate we have considered is the lowest energy ground state

Summary

INTRODUCTION

Neutron stars have been a subject of abiding interest for several decades. There are a variety of astrophysical phenomena that arise from the physics of neutron stars. (iii) The theory gives a qualitatively consistent description for the transition from hadronic matter to quark matter at high density and temperature [4, 5, 13, 14] This L has a single dimensional parameter, fπ, that is the pion decay constant, and three couplings, g3, the QCD coupling, gy, the Yukawa coupling between quarks and mesons, that will be determined from the nucleon mass and the meson-meson coupling, λ, which, for this model, can be determined from meson meson scattering [15]. This discussion is to support the use of our effective lagrangian up to a threshold scale in energy - the compositeness scale Given these facts we use the Mean Field Theory to describe quark matter in the density regime bounded from above by the compositeness scale.

The couplings of L

THE GROUND STATE FOR 3 FLAVOUR QUARK MATTER

NEUTRON STARS FROM OUR EOS

DISCUSSION

Quark matter at even higher density

RESULTS