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

In the present work, we investigate the production mechanism of the $Z_b(10610)$ and $Z_b(10650)$ states from the $\mathrm{{\rm Y}}(5S,6S)$ 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 $B_1^{\mathrm{\prime }}$ resonance could provide the dominant contributions to the $\mathrm{{\rm Y}}(5S)\to Z_b^{(\mathrm{\prime })}\pi$. It is found that such a mechanism is not suppressed by the large width of the $B_0\mathrm{/}{B}_1^{\mathrm{\prime }}$ resonance. In addition, we also estimate the branching ratios for the $\mathrm{{\rm Y}}(6S)\to Z_b^{(\mathrm{\prime })}\pi$ which could be tested by future precise measurements at Belle-II.