Neutron star structure and nuclear matter properties from a general Walecka-type model with Bayesian analysis

We establish a Bayesian analysis framework with a general Walecka-type relativistic mean-field model to study dense nuclear matter under constraints from nuclear matter properties and neutron star observations. With experimental and observational data well described, we find that pure hadronic descriptions can generate a peak structure in sound velocity by $\omega$, $\rho$, $\sigma$, and $a_0$ meson mixing, which is crucial for describing both medium and massive neutron stars. As the peak structure is frequently interpreted as a signature of phase transitions, our findings provide a new perspective on the microscopic origin of the sound velocity peak just with pure hadronic matter.