NA49 and NA61/SHINE experiments: results and perspectives

TL;DR

This paper reviews results from NA49 and NA61/SHINE experiments at SPS, highlighting evidence for deconfinement onset, potential signals of the QCD critical point, and future ion collision studies.

Contribution

It presents experimental signatures of deconfinement and critical point indications in heavy-ion collisions at SPS energies, and discusses future research directions.

Findings

Evidence of deconfinement onset at SPS energies

Possible signals of the QCD critical point in fluctuation data

Future plans for light-ion energy scan at NA61/SHINE

Abstract

The Super Proton Synchrotron (SPS) covers one of the most interesting regions of the QCD phase diagram $(T - \mu_B)$. On the one hand there are indications that the energy threshold for deconfinement is reached already at low SPS energies. On the other hand theoretical calculations locate the QCD critical end-point at energies accessible at the SPS. In this paper the NA49 signatures of the onset of deconfinement are presented. Results are shown on pion production, the kaon to pion ratio, slopes of transverse mass spectra ("temperature"), and event-by-event particle ratio fluctuations versus collision energy, for central $Pb+Pb$ interactions. Next we show possible indications of the critical point in event-by-event mean transverse momentum and multiplicity fluctuations. Finally we discuss the future ion program of the NA61/SHINE experiment (energy scan with light ions).