Dielectron production in proton-proton collisions at $\sqrt{s} = 7$ TeV with ALICE

Abstract

The ALICE Collaboration measured dielectron production as a function of the invariant mass ($m_{\rm ee}$), the pair transverse momentum ($p_{\rm T,ee}$) and the pair distance of closest approach ($\rm DCA_{ee}$) in pp collisions at $\sqrt{s} = 7$ TeV. Prompt and non-prompt dielectron sources can be separated with the $\rm DCA_{ee}$, which will give the opportunity in heavy-ion collisions to identify thermal radiation from the medium in the intermediate-mass range dominated by contributions from open-charm and beauty hadron decays. The charm and beauty total cross sections are extracted from the data by fitting the spectra with two different MC generators, i.e. PYTHIA a leading order event generator and POWHEG a next-to-leading order event generator. Significant model dependences are observed, reflecting the sensitivity of this measurement to the heavy-flavour production mechanisms.