Enhancement of the dielectron continuum in sqrt{s_NN} = 200 GeV Au+Au collisions

TL;DR

This paper reports an enhanced dielectron continuum in high-energy Au+Au collisions, indicating possible medium effects and new sources of dielectron production beyond known hadron decays.

Contribution

First measurement of dielectron continuum in Au+Au collisions at 200 GeV showing significant enhancement and medium-related effects.

Findings

Dielectron yield is enhanced by a factor of 3.4 in the specified mass range.

Yield increases faster than participant nucleons with collision centrality.

Continuum between phi and J/psi masses aligns with c-cbar production expectations.

Abstract

The PHENIX experiment has measured the dielectron continuum in sqrt{s_NN} = 200 GeV Au+Au collisions. In minimum bias collisions the dielectron yield in the mass range between 150 and 750 MeV/c^2 is enhanced by a factor of 3.4 +/- 0.2(stat.) +/- 1.3(syst.) +/- 0.7(model) compared to the expectation from our model of hadron decays. The integrated yield increases faster with the centrality of the collisions than the number of participating nucleons, suggesting emission from scattering processes in the hot and dense medium. The continuum yield between the masses of the phi and the J/psi mesons is consistent with expectations from correlated c-cbar production, though other mechanisms are not ruled out.