Measurement of low-mass dielectrons in pp, p–Pb and Pb–Pb collisions with the ALICE experiment at the LHC

Dielectrons are a unique tool to probe several stages of the space-time evolution of the hot and dense system created in ultra-relativistic heavy ion collisions. They carry unaffected information since once produced they escape the medium with negligible final state interaction. The low- mass region of the dielectron spectrum (below the ρ -meson mass) is interesting for the study of virtual direct photons and possible in-medium modifications of low-mass vector meson spectral functions, that are connected to the partial chiral symmetry restoration expected at high tempera- ture. ALICE is a detector at the LHC dedicated to the study of heavy-ion collisions. Its excellent tracking and particle identification capabilities make this experiment well suited for dielectron measurements. Electrons are reconstructed in the ALICE central barrel using the Inner Tracking System (ITS) and the Time Projection Chamber (TPC). These detectors are also used for the par- ticle identification together with the Time-Of-Flight detector (TOF). We present the ALICE dielectron measurements in pp collisions at 7 TeV (cocktail comparison and virtual photon extraction), in p–Pb collisions at 5.02 TeV (cocktail comparison) and the cur- rent status in central (0–10%) and semi-central (20–50%) Pb–Pb collisions at 2.76 TeV. We also discuss the perspectives for the next runs (Run 2 and Run 3) and the scenario after the ITS and TPC upgrades.