Photon Conversion to Low-Mass Dileptons: Comparing Kroll-Wada and Parton Shower Approaches

by Alexander Neuwirth (UNIMIB & INFN)

Tuesday 21 Oct 2025, 11:30 → 12:30 Europe/Zurich

U2-5017 (Milano-Bicocca)

We study low-mass dielectron production from photon conversions in proton-proton collisions at the LHC, comparing the traditional analytic Kroll-Wada formulation with modern parton shower approaches. Using event generators such as PYTHIA, Vincia, and POWHEG, we investigate how photon-to-dilepton conversion can be modeled consistently within the parton shower framework. This approach naturally incorporates higher-order effects, recoil kinematics, and realistic cuts while preserving normalization through its unitary treatment of internal photon conversions. We find that parton shower simulations reproduce the dilepton spectrum with improved accuracy, particularly at larger invariant masses (2 to 5 GeV) where the Kroll-Wada approximation becomes less reliable.