Quark to $\Lambda$-hyperon spin transfers in the current-fragmentation region

Abstract

We perform a study on the struck quark to the $\Lambda$-hyperon fragmentation processes by taking into account the anti-quark fragmentations and intermediate decays from other hyperons. We concentrate on how the longitudinally polarized quark fragments to the longitudinally polarized $\Lambda$, how unpolarized quark and anti-quark fragment to the unpolarized $\Lambda$, and how quark and anti-quark fragment to the $\Lambda$ through the intermediate decay processes. We calculate the effective fragmentation functions in the light-cone SU(6) quark-spectator-diquark model via the Gribov-Lipatov relation, with the Melosh-Wigner rotation effect also included. The calculated results are in reasonable agreement with the HERMES semi-inclusive $ep$ experimental data and the OPAL and ALEPH $e^{+}{e}^{-}$ annihilation experimental data.

Comments: 14 latex pages, 8 figures. Final version for publication in PLB