Irreducible unitary representations with non-zero relative Lie algebra cohomology of the Lie group $S{O}_0(2,m)$

By a theorem of D. Wigner, an irreducible unitary representation with non-zero $(\mathfrak{g},K)$-cohomology has trivial infinitesimal character, and hence up to unitary equivalence, these are finite in number. We have determined the number of equivalence classes of these representations and the Poincaré polynomial of cohomologies of these representations for the Lie group $S{O}_0(2,m)$ for any positive integer $m\mathrm{.}$ We have also determined, among these, which are discrete series representations and holomorphic discrete series representations.