The strong coupling in the effective quark mass was usually taken as a constant in a quasiparticle model while it is, in fact, running with an energy scale. With a running coupling, however, the thermodynamic inconsistency problem appears in the conventional treatment. We show that the renormalization subtraction point should be taken as a function of the summation of the biquadratic chemical potentials if the quark’s current masses vanish, in order to ensure full thermodynamic consistency. Taking the simplest form, we study the properties of up-down ($ud$) quark matter, and confirm that the revised quasiparticle model fulfills the quantitative criteria for thermodynamic consistency. Moreover, we find that the maximum mass of an $ud$ quark star can be larger than 2 times the solar mass, reaching up to $2.31M_{\odot }$, for reasonable model parameters. However, to further satisfy the upper limit of tidal deformability ${\tilde{\mathrm{\Lambda }}}_{1.4}\le 580$ observed in the event GW170817, the maximum mass of an $ud$ quark star can only be as large as $2.08M_{\odot }$, namely $M_{\max }\lesssim 2.08M_{\odot }$. In other words, our results indicate that the measured tidal deformability for event GW170817 places an upper bound on the maximum mass of $ud$ quark stars, but does not rule out the possibility of the existence of quark stars composed of $ud$ quark matter, with a mass of about 2 times the solar mass.

• Received 5 June 2023
• Accepted 12 August 2023

DOI:https://doi.org/10.1103/PhysRevD.108.054017

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Published by the American Physical Society