Recent results on (anti)nucleus and (anti)hyperon production in nucleus-nucleus collisions at CERN SPS energies

TL;DR

This paper presents comprehensive experimental results on (anti)nucleus and (anti)hyperon production in nucleus-nucleus collisions at CERN SPS energies, analyzing particle yields, spectra, and system size dependence to explore the phase transition to deconfined matter.

Contribution

It provides new measurements of hyperon and light nuclei production across various energies and system sizes, and compares these with statistical and coalescence models to understand strangeness enhancement.

Findings

Remarkable agreement between measured and predicted $^3He$ yields by statistical models.

Observed system size dependence of hyperon yields indicating strangeness enhancement.

Analysis of baryon stopping and spectra across SPS energies and comparison with RHIC and AGS results.

Abstract

The NA49 experiment has collected comprehensive data on particle production in nucleus-nucleus collisions over the whole SPS beam energies range, the critical energy domain where the expected phase transition to a deconfined phase is expected to occur. The latest results from Pb+Pb collisions between 20$A$ GeV and 158$A$ GeV on baryon stopping and light nuclei production as well as those for strange hyperons are presented. The measured data on $p$, $\bar{p}$, $\Lambda$, $\bar{\Lambda}$, $\Xi^-$ and $\bar{\Xi}^+$ production were used to evaluate the rapidity distributions of net-baryons at SPS energies and to compare with the results from the AGS and the RHIC for central Pb+Pb (Au+Au) collisions. The dependence of the yield ratios and the inverse slope parameter of the $m_t$ spectra on the collision energy and centrality, and the mass number of the produced nuclei $^3He$, $t$, $d$ and $\bar{d}$ are discussed within coalescence and statistical approaches. Analysis of the total multiplicity exhibits remarkable agreement between the measured yield for $^3He$ and those predicted by the statistical hadronization model. In addition, new results on $\Lambda$ and $\bar{\Lambda}$ as well as $\Xi^-$ production in minimum bias Pb+Pb reactions at 40$A$ GeV and 158$A$ GeV and central C+C, Si+Si and Pb+Pb collisions are presented. The system size dependence of the yields of these hyperons was analysed to determine the evolution of strangeness enhancement relative to elementary p+p collisions.