Constraints for weakly interacting light bosons from existence of massive neutron stars

TL;DR

This paper investigates how weakly interacting light bosons influence neutron star properties, providing new astrophysical constraints on their couplings, especially in the strange quark sector, and suggesting their role in stiffening nuclear matter.

Contribution

It derives limits on light boson couplings from neutron star observations, highlighting the impact on the equation of state and proposing a vector boson to explain observed stiffness.

Findings

Limits on couplings to strange quarks from neutron stars

Neutron star data suggest a stiffer nuclear matter equation of state

A vector boson coupled to second-family quarks can stiffen nuclear matter

Abstract

Theories beyond the standard model include a number of new particles some of which might be light and weakly coupled to ordinary matter. Such particles affect equation of state of nuclear matter and can shift admissible masses of neutron stars to higher values. The internal structure of neutron stars is modified provided the ratio between coupling strength and mass squared of a weakly interacting light boson is above $g^2/\mu^2 \sim 25 ~\mathrm{GeV}^{-2}$. We provide limits on the couplings with the strange sector, which cannot be achieved from laboratory experiments analysis. When the couplings to the first family of quarks is considered the limits imposed by the neutron stars are not more stringent than the existing laboratory ones. The observations on neutron stars give evidence that equation of state of the $\beta$-equilibrated nuclear matter is stiffer than expected from many-body theory of nuclei and nuclear matter. A weakly interacting light vector boson coupled predominantly to the second family of the quarks can produce the required stiffening.