Centrality dependence of K+ produced in Pb+Pb collisions at 158 GeV per nucleon

TL;DR

This paper investigates how K+ meson production varies with collision centrality in Pb+Pb collisions at 158 GeV per nucleon, seeking signs of a phase transition to quark-gluon plasma through centrality dependence and strangeness enhancement.

Contribution

It provides evidence of a discontinuous change in K+ yield at a specific centrality, indicating the onset of strangeness enhancement and potential QGP formation.

Findings

K+ yield grows proportionally with wounded nucleons above N=100

Discontinuous behaviour observed near N=100 in centrality dependence

Strangeness enhancement suggests a phase transition to QGP

Abstract

The NA52 collaboration searches for a discontinuous behaviour of charged kaons produced in Pb+Pb collisions at 158 A GeV as a function of the impact parameter, which could reveal a hadron to quark-gluon plasma (QGP) phase transition. The K+ yield is found to grow proportional to the number of participating ('wounded') nucleons N, above N=100. Previous NA52 data agree with the above finding and show a discontinuous behaviour in the kaon centrality dependence near N=100, marking the onset of strangeness enhancement -over e.g. p+A data at the same \sqrt{s}- in a chemically equilibrated phase.