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

TL;DR

This paper presents dielectron measurements in pp, p-Pb, and Pb-Pb collisions at the LHC, comparing experimental data to theoretical models to understand medium modifications and electromagnetic radiation in high-energy nuclear collisions.

Contribution

It provides new dielectron spectra measurements across different collision systems and energies, and compares these to theoretical predictions to study medium effects and electromagnetic emissions.

Findings

Dielectron spectra in pp and p-Pb collisions agree with hadronic source expectations.

The direct photon cross section in pp collisions matches NLO pQCD predictions.

Analysis of Pb-Pb collisions is ongoing, aiming to understand hot medium effects.

Abstract

Electromagnetic probes are excellent messengers from the hot and dense medium created in high-energy heavy-ion collisions. Since leptons do not interact strongly, their spectra reflect the entire space-time evolution of the collision. The surrounding medium can lead to modifications of the dielectron production with respect to the vacuum rate. To quantify modifications in heavy-ion collisions, measurements in pp collisions serve as a reference, while the analysis of p-A collisions allows for the disentanglement of cold nuclear matter effects from those of the hot and dense medium. In this proceedings, dielectron measurements with the ALICE central barrel detectors are presented. The invariant mass distributions in the range $ 0<m_{ee}<3 $ GeV/$ c^{2} $ are compared to the expected yields from hadronic sources for pp collisions at $ \sqrt{s}=7 $ TeV, and for p-Pb collisions at $ \sqrt{s_{\rm NN}}=5.02 $ TeV. The cross section of direct photons measured via virtual photons in pp collisions is compared to predictions from NLO pQCD calculations as a function of the transverse momentum. The status of the analysis of Pb-Pb collisions at $ \sqrt{s_{\rm NN}}=2.76 $ TeV is presented.