Identification of possible proton two-quasiparticle band in $^{158}$Sm

High-spin states in neutron-rich $^{158}$Sm have been re-investigated by measuring the prompt $\gamma$-rays emitted in the spontaneous fission of $^{252}$Cf. A new negative-parity band has been established up to spin 12. By comparing with the theoretical calculations [1], a two-quasiparticle proton state with $\pi$5/2[532]$\otimes$$\pi$5/2[413] configuration has been proposed for the band head. The level energies are similar to those of the known levels in the negative two-quasiparticle neutron band [2,3] as predicted by theoretical calculations [1]. The systematics of the two-quasiparticle states and bands in this region are discussed.\\[4pt] [1] Y-C Yang et al., J. Phys. {\bf G37}, 085110 (2010).\\[0pt] [2] S.J. Zhu et al., J. Phys. {\bf G21}, L57 (1995).\\[0pt] [3] G.S. Simpson et al., Phys. Rev. {\bf C80}, 024304 (2009).