Status and new results on the Zb resonances

Abstract

Recently Belle observed two charged bottomonium-like states, Zb(10610) and Zb(10650), that are produced in the Upsilon(5S) -> Zb pi transitions and that decay to Upsilon(nS) pi (n=1,2,3) and h_b(mP) pi (m=1,2) channels. The masses of these states are close to the $B\bar{B}^*$ and $B^*\bar{B}^*$ thresholds, and their favored spin-parities are $J^P=1^+$. We review status and new results on the Zb states, that include the observation of the $Z_b\to B^{(*)}\bar{B}^*$ decays and an evidence for the neutral member of the Zb isotriplet. All properties of the Zb states are consistent with their molecular interpretation.