Observation of Transverse $\hat{I}›/\bar{\hat{I}}›$ Hyperon Polarization in $e^{+}{e}^{-}$ Annihilation at Belle

Abstract

We report the first observation of the spontaneous polarization of $\hat{I}›$ and $\bar{\hat{I}}›$ hyperons transverse to the production plane in $e^{+}{e}^{-}$ annihilation, which is attributed to the effect arising from a polarizing fragmentation function. For inclusive $\hat{I}›/\bar{\hat{I}}›$ production, we also report results with subtracted feed-down contributions from $\hat{I}{\pounds }^0$ and charm. This measurement uses a dataset of 800.4 fb${}^{-1}$ collected by the Belle experiment at or near a center-of-mass energy of 10.58 GeV. We observe a significant polarization that rises with the fractional energy carried by the $\hat{I}›/\bar{\hat{I}}›$ hyperon.

7 pages, 3 figures, plus supplemental material. Submitted to Phys. Rev. Lett