Observation of Transverse Lambda/(Lambda)over-bar Hyperon Polarization in e(+)e(-) Annihilation at Belle

Abstract

We report the first observation of the spontaneous polarization of Lambda and (Lambda) over bar hyperons transverse to the production plane in e(+)e(-) annihilation, which is attributed to the effect arising from a polarizing fragmentation function. For inclusive Lambda/(Lambda) over bar production, we also report results with subtracted feed-down contributions from Sigma(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 Lambda/(Lambda) over bar hyperon.