Spin Partners of the $B^{(\ast )}{\bar{B}}^{(\ast )}$ resonances with a different approach than the Breit-Wigner parameterization

Abstract

In general, resonances are obtained by the Breit-Wigner parameterization. However, it is not entirely appropriate to use this parameterization with near-threshold resonances such as the $Z_b(10610)$ and the $Z_b(10650)$, as Breit-Wigner does not contain the threshold effect. To eliminate this defect, a recently proposed alternative distribution, the Sill, is used to predict possible heavy quark spin symmetry partners of the $Z_b(10610)$ and the $Z_b(10650)$. With the Sill values of the $Z_b(10650)$ and the $Z_b(10610)$ states, assuming these exotics generate molecular states consisting of contact and a pion exchange potential, heavy quark spin symmetry partners are examined with $S$ and $D$-wave contributions. In the light of the Sill type resonance approach, all the partners are found as bound states.

Comments: 8 pages, 3 tables, Accepted for publication in EPJ A