Dilepton measurements with HADES

TL;DR

HADES is a unique dielectron spectrometer investigating electron pair production in heavy ion and elementary reactions at 1-2 AGeV, revealing detailed insights into dielectron yields and their sources.

Contribution

This study provides new measurements of dielectron production in C12+C12 collisions at 1-2 AGeV, highlighting the scaling behavior of excess yields with beam energy.

Findings

Dalitz decays explain yields up to 0.15 GeV/c2

Excess yield scales with pion production

Preliminary results support energy scaling hypothesis

Abstract

HADES is the only operating dielectron spectrometer in the energy regime 1-2 AGeV. The physics program aims at a systematic investigation of dielectron production in heavy ion as well as elementary and pion-induced reactions. This contribution highlights recent results on electron pair production in C12+C12 collisions at an incident energy of 2 AGeV with HADES. The measured pair production probabilities span over five orders of magnitude. Dalitz decays of pi0 and eta account for all the yield up to 0.15 GeV/c2, but for only about 50% above this invariant mass. The excess yield compared to the hadronic cocktail between the pi0-Dalitz and the rho/omega invariant-mass region is in agreement with the former DLS result if one assumes that it scales with beam energy like pion production. Preliminary results from C12+C12 collisions at an incident energy of 1 AGeV support this scenario.