Meson and di-electron production with HADES

TL;DR

This paper reports on measurements of di-electron production in various nuclear collisions using the HADES experiment, highlighting the role of resonances in dense nuclear matter.

Contribution

It provides the first reference cocktail for long-lived di-electron sources and analyzes the early collision phase by subtracting these from inclusive yields.

Findings

Resonances significantly influence di-electron production in dense matter.

Exclusive pi0 and eta Dalitz decays reconstructed at 2.2 GeV.

Subtraction method reveals early collision signals.

Abstract

The HADES experiment, installed at GSI, Darmstadt, measures di-electron production in A+A, p/pi+N and p/pi+A collisions. Here, the pi0 and eta Dalitz decays have been reconstructed in the exclusive p+p reaction at 2.2 GeV to form a reference cocktail for long-lived di-electron sources. In the C+C reaction at 1 and 2 GeV/u, these long-lived sources have been subtracted from the measured inclusive e+e- yield to exhibit the signal from the early phase of the collision. The results suggest that resonances play an important role in dense nuclear matter.