Connected (n,m)-point functions of diagonal 2-BKP tau-functions and spin double Hurwitz numbers

We derive an explicit formula for connected (n, m)-point functions associated with an arbitrary diagonal tau-function of the 2-BKP hierarchy using the computation of neutral fermions and boson–fermion correspondence of type B and then apply this formula to the computation of connected spin double Hurwitz numbers. This is the type B analog of Wang and Yang [arXiv:2210.08712 (2022)].