Dileptons at Colliders as Probes of the Quark-Gluon Plasma

Abstract

Ultra-relativistic heavy-ion collisions are used to create a deconfined state of quarks and gluons, the quark-gluon plasma (QGP), similar to the matter in the early universe. Dileptons are a unique probe of the QGP. Being emitted during all stages of the collision without interacting strongly with the surrounding matter, they carry undistorted information about the medium evolution. The mass of the lepton-antilepton pair gives a unique mean to separate partonic from hadronic radiation. Thus, dileptons can be used to study the QGP equilibration time, its average temperature but also effects related to the restoration of chiral symmetry in the hot medium via vector meson decays. This information is not accessible with hadrons. The price to pay is a large background from ordinary hadron decays. We summarize the potential of dilepton measurements, the results obtained so far at colliders, and the ongoing efforts for future experiments with further increased sensitivity.

References in corpus (9)

• Evidence for the production of thermal muon pairs with masses above 1 GeV/c^2 in 158A GeV Indium-Indium Collisions
• Multi-messenger heavy-ion collision physics
• Intermediate mass dileptons as pre-equilibrium probes in heavy ion collisions
• Diffusion coefficient matrix of the strongly interacting quark-gluon plasma
• Dilepton production at next-to-leading order and intermediate invariant-mass observables
• Virtual Photons Shed Light on the Early Temperature of Dense QCD Matter
• Dilepton polarization as a signature of plasma anisotropy
• Transverse mass scaling of dilepton radiation off a quark-gluon plasma
• Electrical conductivity of the quark-gluon plasma from the low energy limit of photon and dilepton spectra