A corresponding-state approach to quark-cluster matter

TL;DR

This paper proposes a phenomenological equation of state for quark-cluster matter in dense stars using a corresponding-state approach, suggesting such stars could explain observed pulsar masses and discussing phase transition effects.

Contribution

It introduces a novel application of the corresponding-state method to model quark-cluster matter in compact stars, bridging observational constraints and theoretical modeling.

Findings

Quark-cluster stars can have high maximum masses consistent with observations.

The equation of state derived supports the existence of stable quark-cluster matter in pulsars.

Discussion of melting heat effects during phase transitions in quark matter.

Abstract

The state of super-dense matter is essential for us to understand the nature of pulsars, but the non- perturbative quantum chromodynamics (QCD) makes it very difficult for direct calculations of the state of cold matter at realistic baryon number densities inside compact stars. Nevertheless, from an observational point of view, it is conjectured that pulsars could be made up of quark clusters since the strong coupling between quarks might render quarks grouped in clusters. We are trying an effort to find an equation of state of condensed quark-cluster matter in a phenomenological way. Supposing that the quark-clusters could be analogized to inert gases, we apply here the corresponding-state approach to derive the equation of state of quark-cluster matter, as was similarly demonstrated for nuclear and neutron-star matter in 1970s. According to the calculations presented, the quark-cluster stars, which are composed of quark-cluster matter, could then have high maximum mass that is consistent with observations and, in turn, further observations of pulsar mass would also put constraints to the properties of quark-cluster matter. Moreover, the melting heat during solid-liquid phase conversion and the related astrophysical consequences are also briefly discussed.