Results from ALICE

TL;DR

The ALICE experiment at CERN studies high-energy nuclear collisions to understand hot, dense nuclear matter, providing data that challenge existing models, especially regarding strangeness production and particle suppression in heavy-ion collisions.

Contribution

This paper reports the first results from ALICE at the LHC, including new data on proton-proton and lead-lead collisions that constrain models of nuclear matter under extreme conditions.

Findings

Strangeness production in pp collisions challenges Monte Carlo models.

Particle suppression observed in Pb+Pb collisions at LHC energies.

Data provides new constraints for theoretical models of nuclear matter.

Abstract

The ALICE experiment at the Large Hadron Collider at CERN is optimized to study the properties of the hot, dense matter created in high energy nuclear collisions in order to improve our understanding of the properties of nuclear matter under extreme conditions. In 2009 the first proton beams were collided at the Large Hadron collider and since then data from proton-proton collisions at $\sqrt{s}$ = 0.9, 2.36, 2.76, and 7 TeV have been taken. Results from pp collisions provide significant constraints on models. In particular, results on strange particles indicate that Monte Carlo generators still have considerable difficulty describing strangeness production. In 2010 the first lead nuclei were collided at $\sqrt{s_{NN}}$ = 2.76 TeV. Results from Pb+Pb demonstrate suppression of particle production relative to that observed in pp collisions, consistent with expectations based on data available at lower energies.