Polarization and forward-backward asymmetry of $\Lambda$ baryons in hadronic Z$^0$ decays

OPAL Collaboration:     K. Ackerstaff - et al.

doi:doi:10.1007/s100520050123

EPJ

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2022 Impact factor 4.4

Particles and Fields

Eur. Phys. J. C 2, 49-59

Polarization and forward-backward asymmetry of $\Lambda$ baryons in hadronic Z⁰ decays

OPAL Collaboration, K.Ackerstaff⁸ et al.

⁸ CERN, European Organisation for Particle Physics, CH-1211 Geneva 23, Switzerland

Received: 30 July 1997

Abstract
The longitudinal polarization, the transverse polarization, and the forward-backward asymmetry of $\Lambda$ baryons, have been measured using a sample of 4.34 million hadronic $\mathrm{Z}^0$ decays collected with the OPAL detector at LEP between 1990 and 1995. These results are important as an aid to the understanding of hadronization mechanisms. Significant longitudinal polarization has been observed at intermediate and high momentum. For x_E ( $\equiv 2 E_{\Lambda}/\sqrt{s}) \gt$ 0.3, the longitudinal polarization has been measured to be $-32.9 \pm 5.5$ (stat) $\pm$ 5.2 (syst)%. We have observed no transverse polarization. A significant forward-backward asymmetry has been measured and can be described by a JETSET model.