Neutron star mass limit at $2M_{\odot }$ supports the existence of a CEP

Abstract

We point out that the very existence of a "horizontal branch" in the mass-radius characteristics for neutron stars indicates a strong first-order phase transition and thus supports the existence of a critical endpoint (CEP) of first order phase transitions in the QCD phase diagram. This branch would sample a sequence of hybrid stars with quark matter core, leading to the endpoint of stable compact star configurations with the highest possible baryon densities. Since we know of the existence of compact stars with $2M_{\odot }$, this hypothetical branch has to lie in the vicinity of this mass value, if it exists. We report here a correlation between the maximal radius of the horizontal branch and the pressure at the onset of hadron-to-quark matter phase transition which is likely to be a universal quantity of utmost relevance to the upcoming experiments with heavy-ion collisions at NICA and FAIR.

9 pages, 3 figures, accepted for publication in Eur. Phys. J. A

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• Chiral symmetry restoration and the $\Delta$ matter formation in neutron stars
• Revisiting the Equation of State of Hybrid Stars in the Dyson-Schwinger Equation Approach to QCD
• Hybrid stars with large strange quark cores constrained by GW170817
• Studying VLOCV twin compact stars with binary mergers
• Towards generating a new supernova equation of state: A systematic analysis of cold hybrid stars
• Charged anisotropic compact objects obeying Karmarkar condition
• Recent selected theory developments for NICA