Dielectron measurements in pp, p-Pb, and Pb-Pb collisions with the ALICE detector

Dielectrons are excellent tools to investigate the properties of the medium created in heavy-ion collisions. Since dielectrons generated in the medium are not affected by final state interactions, they carry information about the space-time evolution of the collision. The dielectron invariant mass shape is expected to be sensitive to the in-medium modification of vector mesons and thermal radiation from the hot medium created in heavy-ion collisions. In order to understand the nuclear effects, dielectron measurements in pp collisions serve as reference, while p-A collisions are important for the evaluation of the cold nuclear matter effects on the modification of the invariant mass shape. In this proceedings, the dielectron measurements with the ALICE central barrel detectors are presented. The invariant mass spectra in pp at s=7 TeV and p-Pb collisions at sNN=5.02 TeV are extracted and in agreement with the estimated hadronic cocktail calculation. The cross section of the direct photons measured via virtual photons is consistent with NLO pQCD calculations within uncertainties. The uncorrected dielectron yields are also extracted in central and semi-central Pb-Pb collisions at sNN=2.76 TeV . The performance study of the dielectron excess measurement in Pb-Pb collisions by the ALICE detector upgrade is also discussed.