String model description of polarisation and angular distributions in $\mth{\overline{p}p\rightarrow\overline{\Lambda}\Lambda}$ at low energies

S. Pomp; G. Ingelman; T. Johansson; S. Ohlsson

doi:doi:10.1140/epja/i2002-10060-6

EPJ

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2019 Impact factor 2.176

Hadrons and Nuclei

Eur. Phys. J. A 15, 517-522 (2002)
DOI: 10.1140/epja/i2002-10060-6

String model description of polarisation and angular distributions in $\mth{\overline{p}p\rightarrow\overline{\Lambda}\Lambda}$ at low energies

S. Pomp, G. Ingelman, T. Johansson and S. Ohlsson

Department of Radiation Sciences, Uppsala University, Box 535, S-75121 Uppsala, Sweden

Stephan.Pomp@tsl.uu.se

(Received: 2 April 2002 / Revised version: 8 July 2002 / Published online: 3 December 2002)

Abstract
The observed polarisation of $\Lambda$ hyperons from the inclusive $pA \rightarrow \Lambda X$ reaction at high energies has previously been well described within the Lund string model through polarised $s\bar{s}$ quark pair production in the string breaking hadronisation process. This model is here applied to the exclusive $\overline{p}p\rightarrow\overline{\Lambda}\Lambda$ $\overline{p}p\rightarrow\overline{\Lambda}\Lambda$ reaction at low energies and compared to available data sets down to an incident-beam momentum of 1.835 GeV/ c. This required an extension of the diquark scattering model to involve three components: an isotropic part relevant close to the threshold, a spectator part and a forward-scattering part as in $pA \rightarrow \Lambda X$ at high energies. The observed angular distributions are then reproduced and, for momentum transfers above |t'| = 0.2 GeV ², agreement with the measured polarisation is also obtained.