What have we learned and want to learn from heavy ion collisions at CERN SPS?

TL;DR

This paper reviews the current understanding of heavy ion collisions at CERN SPS, focusing on evidence for quark-gluon plasma formation and identifying key areas needing further research.

Contribution

It provides a comprehensive overview of SPS heavy ion program status and discusses future directions for confirming quark-gluon plasma production.

Findings

Progress towards confirming QGP at SPS

Identification of missing evidence for QGP

Emphasis on future research directions

Abstract

The talk is a mini-review of the current status of the field, with emphasis on SPS heavy ion program, now and beyond 2000 (as asked by the organizers). The main question is, of course, whether we can convince ourselves and the community at large that the QGP is in fact produced at SPS. We came a long way toward the positive answer, and are definitely on strongly rising part of the learning curve. Still, in few key directions we lack important pieces of evidences.