NA49 evidence for the onset of deconfinement

TL;DR

The NA49 experiment's beam energy scan indicates the onset of deconfinement in heavy-ion collisions around 30A GeV, with models needing extensions to match observed data.

Contribution

This paper reviews experimental evidence for the deconfinement phase transition onset using particle yields and spectral data from NA49.

Findings

Deconfinement likely begins at ~30A GeV in heavy-ion collisions.

Standard models fail to fully explain the energy dependence of data.

Additional parameters or states are needed in models to fit observations.

Abstract

We review the experimental results obtained by the NA49 collaboration in the context of its beam energy scan programme. The data on particle yields and spectral distributions suggest that the deconfinement phase transition is first reached in central collisions of heavy nuclei at about 30A GeV beam energy. Hadron-string transport models as well as the hadron gas model fail to describe the observed energy dependences unless additional parameters or unmeasured states are included.