Remarks about a generalized pseudo-relativistic Hartree equation

With appropriate hypotheses on the nonlinearity $f$, we prove the existence of a ground state solution $u$ for the problem $$(-\mathrm{\Delta }+m^2{)}^{\sigma }u+Vu=(W\ast F(u))f(u)\text{ in }{\mathbb{R}}^N,$$ where $0<\sigma <1$, $V$ is a bounded continuous potential and $F$ the primitive of $f$. We also show results about the regularity of any solution of this problem.