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Abstract

We consider the capture of dark matter (DM) in neutron stars via
scattering on hadronic targets, including neutrons, protons and
hyperons. We extend previous analyses by including momentum dependent
form factors, which account for hadronic structure, and incorporating
the effect of baryon strong interactions in the dense neutron star
interior, rather than modelling the baryons as a free Fermi gas. The
combination of these effects suppresses the DM capture rate over a wide
mass range, thus increasing the cross section for which the capture rate
saturates the geometric limit. In addition, variation in the capture
rate associated with the choice of neutron star equation of state is
reduced. For proton targets, the use of the interacting baryon approach
to obtain the correct Fermi energy is essential for an accurate
evaluation of the capture rate in the Pauli-blocked regime. For heavy
neutron stars, which are expected to contain exotic matter, we identify
cases where DM scattering on hyperons contributes significantly to the
total capture rate. Despite smaller neutron star capture rates, compared
to existing analyses, we find that the projected DM-nucleon scattering
sensitivity greatly exceeds that of nuclear recoil experiments for a
wide DM mass range.