Nonperturbative study of quantum many-body correlation effects in neutron stars: Equation of state

Although neutron stars have been studied for decades, their internal structure remains enigmatic, mainly due to large uncertainties in the equation of state. In neutron stars, the nucleons are strongly interacting by exchanging mesons, which can lead to significant quantum many-body correlation effects. Mean-field calculations failed to capture these effects. Here, we develop a nonperturbative quantum field-theoretic approach to handle strongly correlated dense nuclear matter within the framework of quantum hadrodynamics. We show that the many-body effects can be incorporated in the Dyson-Schwinger equation of the nucleon propagator. Based on a linear $\sigma \text{−}\omega \text{−}\rho$ model, we successfully reproduce six empirical observable quantities of saturation nuclear matter by tuning six parameters. After including the many-body effects into the equation of state of realistic neutron star matter, we obtain a mass-radius relation that is comparable with recent astrophysical observations of neutron stars.