Low-Mass Dielectron Production in pp, p-Pb and Pb-Pb Collisions with ALICE

TL;DR

This paper reports measurements of low-mass dielectron production in different collision systems at the LHC, comparing results with theoretical models and exploring future measurement prospects after detector upgrades.

Contribution

It provides new dielectron production data across pp, p-Pb, and Pb-Pb collisions, and assesses the potential for future temperature measurements post-upgrade.

Findings

Dielectron yields in p-Pb agree with hadronic cocktail.

In Pb-Pb, background-subtracted yields vary with centrality.

The virtual photon production matches NLO pQCD predictions.

Abstract

The ALICE Collaboration measures the production of low-mass dielectrons in pp, p-Pb and Pb-Pb collisions at the LHC. The main detectors used in the analyses are the Inner Tracking System, Time Projection Chamber and Time-Of-Flight detector, all located at mid-rapidity. The dielectron yield in p-Pb collisions shows an overall agreement with the hadronic cocktail. The pair transverse momentum distributions are sensitive to the contributions from open heavy-flavours. In Pb-Pb collisions, uncorrected background-subtracted yields have been extracted in two centrality classes. In pp collisions the production of virtual photons relative to the inclusive yield is determined by analyzing the dielectron excess with respect to the expected hadronic sources. The direct photon cross section is then calculated and found to be in agreement with NLO pQCD calculations. A feasibility study for LHC Run 3 after the ALICE upgrade indicates the possibility for a future measurement of the early effective temperature.