Early times and thermalization in heavy ion collisions: a summary of experimental results for photons, light vector mesons, open and hidden heavy flavors

TL;DR

This paper reviews experimental results on electromagnetic probes like photons and dileptons from high-energy proton and heavy ion collisions, shedding light on the properties of the hot, dense matter created in such events.

Contribution

It summarizes a wide range of dilepton and photon measurements across different energies and experiments, providing insights into the matter formed in heavy ion collisions.

Findings

Dilepton spectra measured from $c0$ to $a9$ mass range.

Results indicate modifications of vector mesons in medium.

Data suggest thermal radiation contributions to dilepton yields.

Abstract

This contribution summarizes the main experimental results presented at the 2009 Quark Matter conference concerning single and dilepton production in proton and heavy ion collisions at high energy. The dilepton invariant mass spectrum has been measured over a range that extends from the $\pi^0$ mass to the $\Upsilon$ mass, and for various collision energies at SPS, Fermilab, Hera and RHIC. This paper focuses on the various contributions (photons, low mass vector mesons, open and hidden heavy flavors) to this spectrum and discuss their implications on our understanding of the matter formed in heavy ion collisions.