Prospects for the spin structure study of hyperons using heavy quark decays at Belle II

Abstract

In weak decays of heavy quarks, the daughter quarks are highly polarized. On the other hand, one can naively expect that the fraction of the baryon spin carried by a quark is equal to the polarization transfer of the quark to the baryon. In this way, one can experimentally determine the spin structures of hyperons in decays of heavy quarks. Spin structures of ground state hyperons ( i.e., $\Lambda$ and $\Sigma$ ) are interesting in the context of the proton spin structure puzzle. In addition, excited states can be also studied to identify exotic hyperons, especially $\Lambda(1405)$. With the high luminosity expected from the Belle II experiment, polarization of $\Lambda(1405)$, as well as ground $\Lambda$ and $\Sigma$, can be measured to determine its spin structure.