NA49 evidence for the onset of deconfinement

Understand

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.