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arXiv · 1905.01005

Effective repulsion in dense quark matter from non-perturbative gluon exchange

Yifan Song·Gordon Baym·Tetsuo Hatsuda·Toru Kojo
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Abstract

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.

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Yifan Song, Gordon Baym, Tetsuo Hatsuda, Toru Kojo. 2019-05-03. Effective repulsion in dense quark matter from non-perturbative gluon exchange. https://doi.org/10.1103/physrevd.100.034018

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