The Effect of Quantum Fluctuations in the High-Energy Cold Nuclear Equation of State and in Compact Star Observables

TL;DR

This paper introduces a new FRG-based method to precisely determine the equation of state for nuclear matter, revealing quantum fluctuations significantly influence compact star properties.

Contribution

The authors develop an exact FRG technique for EoS calculation and demonstrate its impact on compact star observables, surpassing traditional approximations.

Findings

10-20% difference between FRG and other approximations in EoS

Quantum fluctuations cause about 5% variation in star mass-radius relations

New method improves understanding of dense nuclear matter in astrophysics

Abstract

We present a novel technique to obtain exact equation of state (EoS) by the Functional Renormalization Group (FRG) method, using the expansion of the effective potential in a base of harmonic functions at finite chemical potential. Within this theoretical framework we determined the equation of state and the phase diagram of a simple model of massless fermions coupled to scalars through Yukawa-coupling at the zero-temperature limit. We compared our results to the 1-loop and the mean field approximation of the same model and other high-density nuclear matter equation of states. We found a $10-20\%$ difference between these approximations. As an application, we used our exact, FRG-based equation of states to test the effect of the quantum fluctuations in superdense nuclear matter of a compact astrophysical object for the first time. We calculated the mass-radius relation for a compact star using the Tolmann-Oppenheimer-Volkov equation and observed a $\sim 5\%$ effect in compact star observables due to quantum fluctuations.