Proton and neutron correlations in 10B

We investigate positive-parity states of B-10 with the calculation of antisymmetrized molecular dynamics focusing on pn pair correlations. We discuss effects of the spin-orbit interaction on energy spectra and pn correlations of the J(pi)T = 1(1)(+)0, 3(1)(+)0, and 0(1)(+)1 states. The 1(1)(+)0 state has almost no energy gain of the spin-orbit interaction, whereas the 3(1)(+)0 state gains the spin-orbit interaction energy largely to come down to the ground state. We analyze the spin-orbit interaction dependence of the B-10 spectra and find that the ordering of the 3(1)(+)0 and 1(1)(+)0 states is sensitive to the spin-orbit interaction. We also apply a 2 alpha + pn model to discuss effects of the spin-orbit interaction on T = 0 and T = 1 pn pairs around the 2 alpha core. In the spin-aligned J(pi)T = 3(+)0 state, the spin-orbit interaction affects the (ST) = (10) pair attractively and keeps the pair close to the core, whereas, in the 1(+)0 state, it gives a minor effect to the (ST) = (10) pair. In the 0(+)1 state, the (ST) = (01) pair is somewhat dissociated by the spin-orbit interaction.