Cascade and anti-cascade production in central Pb+Pb collisions at 158 GeV/c per nucleon

TL;DR

This paper reports on the first measurement of 4pi integrated yields of Xi and Xi-bar hyperons in central Pb+Pb collisions at 158 GeV/c per nucleon, revealing their production characteristics and ratios.

Contribution

It introduces a global reconstruction method enabling full phase space yield measurements of hyperons in heavy-ion collisions.

Findings

Measured central rapidity densities for Xi and Xi-bar hyperons.

Determined full phase space yields for Xi and Xi-bar hyperons.

Calculated the Xi-bar/Xi ratio at mid-rapidity.

Abstract

Results of the production of Xi and Xi-bar hyperons in central Pb+Pb interactions at 158 GeV/c per nucleon are presented. This analysis utilises a global reconstruction procedure, which allows a measurement of 4pi integrated yields to be made for the first time. Inverse slope paramters, which are determined from an exponential fit to the transverse mass spectra, are shown. Central rapidity densities are found to be 1.49 +- 0.08 and 0.33 +- 0.04 per event per unit of rapidity for Xi and Xi-bar respectively. Yields integrated to full phase space are 4.12 +- 0.02 and 0.77 +- 0.04 for Xi and Xi-bar. The ratio of Xi-bar/Xi at mid-rapidity is 0.22 +- 0.03.