Production of the $Z_b^{(\prime )}$ states from the ${\rm Y}(5S,6S)$ decays

Abstract

In the present work, we investigate the production mechanism of the $Z_b(10610)$ and $Z_b(10650)$ states from the ${\rm Y}(5S,6S)$ decays. Two types of bottom-meson loops are discussed. We show that the loop contributions with all intermediate states being the $S$-wave ground state bottom mesons are negligible, while the loops with one bottom meson being the broad $B_0^{\ast }$ or $B_1^{\prime }$ resonance could provide the dominant contributions to the ${\rm Y}(5S)\to Z_b^{(\prime )}\pi$. It is found that such a mechanism is not suppressed by the large width of the $B_0/B_1^{\prime }$ resonance. In addition, we also estimate the branching ratios for the ${\rm Y}(6S)\to Z_b^{(\prime )}\pi$ which could be tested by future precise measurements at Belle-II.

Comments: Published version