Low-Mass Dileptons and Virtual Photon Production
Internal conversion of real and virtual photons into low-invariant-mass lepton pairs, comparing the Kroll-Wada formalism with parton-shower descriptions.
Low-invariant-mass lepton-pair production is a sensitive observable in both proton-proton and heavy-ion collisions: dilepton pairs arise from the internal conversion of real and virtual photons, making them an experimentally accessible proxy for photon production itself, and a probe of the quark-gluon plasma. The classic Kroll-Wada formalism and the related soft-photon / Low-Burnett-Kroll approximations provide a simple, universal description of this conversion, but their accuracy away from the strict soft limit is not guaranteed.
This research compares the Kroll-Wada approach with an explicit parton-shower treatment of virtual-photon emission and conversion, and separately quantifies the virtual-photon signal against background contributions from heavy-flavour (charm and bottom) decays in di-electron final states, relevant for measurements such as those from PHENIX, ALICE and STAR.
Published results
- Conversion of Photons to Dileptons in the Kroll-Wada and Parton Shower Approaches (JHEP 03 (2026) 024)
- Di-Electron Production at the LHC: Unravelling Virtual-Photon and Heavy-Flavour Contributions (JHEP 05 (2024) 222)
Ongoing and future work
- Recoil corrections and soft-photon kinematics beyond the strict soft-photon approximation.
- Low-transverse-momentum photon and dilepton production.
- Further comparison with heavy-ion dilepton measurements.