Effective repulsion in dense quark matter from non-perturbative gluon exchange. (arXiv:1905.01005v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Song_Y/0/1/0/all/0/1">Yifan Song</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Baym_G/0/1/0/all/0/1">Gordon Baym</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hatsuda_T/0/1/0/all/0/1">Tetsuo Hatsuda</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kojo_T/0/1/0/all/0/1">Toru Kojo</a>
A moderately strong vector repulsion between quarks in dense quark matter is
needed to explain how a quark core can support neutron stars heavier than two
solar masses. We study this repulsion, parametrized by a four-fermion
interaction with coupling g_V, in terms of non-perturbative gluon exchange in
QCD in the Landau gauge. Matching the energy of quark matter, g_V n_q^2 (where
n_q is the number density of quarks) with the quark exchange energy calculated
in QCD with a gluon propagator parametrized by a finite gluon mass m_g and a
frozen coupling alpha_s, at moderate quark densities, we find that gluon masses
m_g in the range 200 – 600 MeV and alpha_s = 2 – 4 lead to a g_V consistent
with neutron star phenomenology. Estimating the effects of quark masses and a
color-flavor-locked (CFL) pairing gap, we find that g_V can be well
approximated by a flavor-symmetric, decreasing function of density. We briefly
discuss similar matchings for the isovector repulsion and for the pairing
attraction.
A moderately strong vector repulsion between quarks in dense quark matter is
needed to explain how a quark core can support neutron stars heavier than two
solar masses. We study this repulsion, parametrized by a four-fermion
interaction with coupling g_V, in terms of non-perturbative gluon exchange in
QCD in the Landau gauge. Matching the energy of quark matter, g_V n_q^2 (where
n_q is the number density of quarks) with the quark exchange energy calculated
in QCD with a gluon propagator parametrized by a finite gluon mass m_g and a
frozen coupling alpha_s, at moderate quark densities, we find that gluon masses
m_g in the range 200 – 600 MeV and alpha_s = 2 – 4 lead to a g_V consistent
with neutron star phenomenology. Estimating the effects of quark masses and a
color-flavor-locked (CFL) pairing gap, we find that g_V can be well
approximated by a flavor-symmetric, decreasing function of density. We briefly
discuss similar matchings for the isovector repulsion and for the pairing
attraction.
http://arxiv.org/icons/sfx.gif
