Energy dependence of phi meson production in central Pb+Pb collisions at sqrt(s_nn) = 6 to 17 GeV

TL;DR

This study investigates how phi meson production varies with collision energy in central Pb+Pb collisions, suggesting the onset of partonic degrees of freedom at certain energies based on experimental data and model comparisons.

Contribution

It provides new measurements of phi meson production across a range of energies and compares these with models to explore the transition to partonic matter.

Findings

Energy dependence of yields supports partonic onset at SPS energies.

Data aligns with thermal and microscopic model predictions.

Indicates a transition in the underlying physics at specific energies.

Abstract

Phi meson production is studied by the NA49 Collaboration in central Pb+Pb collisions at 20A, 30A, 40A, 80A and 158A GeV beam energy. The data are compared with measurements at lower and higher energies and to microscopic and thermal models. The energy dependence of yields and spectral distributions is compatible with the assumption that partonic degrees of freedom set in at low SPS energies.