简介: |
Dilepton spectra in heavy-ion collisions directly probe the in-medium modifications of the electromagnetic spectral function. At low mass, the latter is dominated by the rho-meson while at high mass it is characterized by a perturbative quark-antiquark continumm. Thus, dilepton spectra in the low-mass region can reveal the fate of hadrons as the QCD transition is approached, while at high mass one can extract information on the temperature of the produced medium.
We discuss the current status in calculating dilepton emission rates and what we have learned from the pertinent phenomenology in heavy-ion collisions. In particular, we will analyze the implications for hadron properties as the QCD transition is approached and relations to the long-standing question of how chiral symmetry restoration is realized. We then outline how in the future dileptons can be used as a universal tool to extract the temperature and lifetime of the fireballs produced across a large range of heavy-ion
collision energies.
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