Dynamically generated momentum space shell structure of quarkyonic matter via an excluded volume model

Abstract

The phase space structure of zero temperature Quarkyonic matter is a Fermi sphere of Quark Matter, surrounded by a shell of Nucleonic matter. We construct a quasi particle model of Quarkyonic Matter based on the constituent quark model, where the quark and nucleon masses are related by mQ = mN /Nc, and Nc is the number of quark colors. The region of occupied states is for quarks kQ < kF /Nc, and for nucleons kF < kN < kF + ∆. We first consider the general problem of Quarkyonic Matter with hard core nucleon interactions. We then specialize to a quasi-particle model where the hard core nucleon interactions are accounted for by an excluded volume. In this model, we show that the nucleonic shell forms past some critical density related to the hard core size, and for large densities becomes a thin shell. We explore the basic features of such a model, and argue this model has the semi-quantitative behaviour needed to describe neutron stars.

Speed of sound and quark confinement inside neutron stars

“…We note that the sequential appearance stays in contrast to the isospin-symmetric case, where quarks deconfine simultaneously, owing to the isospin symmetry [29]. Such separation of the chirally broken and the deconfined phase might indicate the existence of a quarkyonic phase, where the quarks are partly confined to form a Fermi sphere, but the relevant degrees of freedom around the Fermi surface remain the nucleons with the restored chiral symmetry [50][51][52][53][54][55].…”

Holographic quarkyonic matter

“…Recently, a simple model of (chirally broken) quarkyonic matter was proposed [11], based on the picture of a Fermi sea filled by quarks surrounded by a baryon layer. This model has been extended and applied to the physics of neutron stars [12][13][14][15].…”

A field theoretical model for quarkyonic matter

“…We note that our results are consistent with those given in refs. [18,20] for both small and large density, except that the prominent peak structure in the intermediate density is absent in our model. The difference could be due to the hard core feature in ref.…”

“…The difference could be due to the hard core feature in ref. [20] which we do not have. Actually, the monotonous feature of C v was also found in a recent study when diquark dynamics is ignored [34].…”

“…[14]. Recently, there has been increasing interest to explore the possible existence of quarkyonic matter inside compact stars or in heavy ion collisions, and the relevant consequences for astrophysical and experimental observations [15][16][17][18][19][20][21][22][23][24][25].…”