Transverse and Longitudinal Lambda Polarization in Lepton Scattering by Unpolarized Nucleons at HERMES

G. Karyan

doi:10.1142/s2010194516600673

Abstract

Transverse and longitudinal polarization of [Formula: see text] hyperons has been studied. The transfere of polarization from high-energy positron to [Formula: see text] hyperon has been measured. The longitudinal spin transverse coefficient is found to be [Formula: see text] = [Formula: see text]. The transverse polarization of [Formula: see text] and [Formula: see text] hyperons has been measured in inclusive quasireal photoproduction process for various target nuclei. The polarization observed is positive for light target nuclei and compartaible with zero for heavy target nuclei.

Highlights

A study of Λ polarization, i.e. the polarization of the ligthest hyperon with strange quark content has an important role
The measurements of the longitudinal spin trasnfer from longitudinally polarized beam leptons to the Λ hyperon are sensitive to two unknowns : the spin structure of the Λ and the spin-dependent dynamics of the fragmentation process in deep-inelastic scattering
When a longitudinally-polarized lepton beam is scattered at high energies from a nucleon target, angular momentum conservation dictates that quarks of a particular spin orientation participate predominantly in the interaction

Summary

Introduction

A study of Λ polarization, i.e. the polarization of the ligthest hyperon with strange quark content has an important role. When a longitudinally-polarized lepton beam is scattered at high energies from a nucleon target, angular momentum conservation dictates that quarks of a particular spin orientation participate predominantly in the interaction. The outgoing struck quark is polarized, and hyperons produced from its fragmentation may “remember” its spin orientation and carry a longitudinal polarization themselves. Such a correlation may be expressed in terms of a spin-dependent fragmentation function GΛ1f (z) Ref. 1. The Λ hyperons were accumulated by the HERMES spectrometer at DESY In this measurements, the 27.6 GeV longitudinally polarized and unpolarized positron beams are passed through an open-ended tubular storage cell into which polarized or unpolarized target atoms in undiluted gaseous form are continuously injected.

STEEL PLATE

Results

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