Overview and Recent Results from BRAHMS

TL;DR

The BRAHMS experiment studied particle production in heavy ion collisions, revealing rapidity-dependent features, gluon saturation effects at forward rapidities, and the importance of final state effects in high- extit{p}T suppression.

Contribution

This paper summarizes recent BRAHMS results, highlighting new insights into rapidity dependence, gluon saturation, and the nature of high- extit{p}T suppression in heavy ion collisions.

Findings

Bulk properties at high rapidity resemble lower energy mid-rapidity systems.

High- extit{p}T suppression is a final state effect.

Strong pion suppression at forward rapidities in d+A collisions.

Abstract

The BRAHMS experiment was designed to measure and characterize in particular the properties of rapidity dependence of particle production in heavy ion collisions. The data-taking is now over, results of several years of analysis have been published and demonstrates several important features of the rapidity dependence, not envisioned from the start of the RHIC program. The bulk properties of the system formed at high rapidity resemble that of systems at lower energies at mid-rapidity when referenced via the baryo-chemical potential. New physics in AA are essentially observed at mid-rapidity including the demonstration that high-\pT suppression is a final state effect. Another key result is that in d+A collisions at forward rapidities where the very low-x region of the nucleus was probed, a strong suppression of pion production was observed consistent with the picture of gluon saturation. The latest results examines the centrality and rapidity dependence of nuclear stopping, the particle production of pions, collective expansion vs. rapidity, and the baryon enhancement at intermediate values of \pT .