Drell-Yan Production Using a New Approach PDF2ISR in the PYTHIA Event Generator

We present PDF2ISR, a new method for constructing an initial partem shower consistent with parton densities, applied to Drell-Yan production. Implemented in the PYTHIA8 event generator, it incorporates the Parton Branching framework to modify the initial-state shower. Predictions are systematically validated against those from the CASCADE3 generator, which also employs the Parton Branching method and the same parton densities, including transverse-momentum-dependent distributions. After confirming the consistency of the modified initial-state showers with the Parton Branching method, we apply PDF2ISR to generate full Drell-Yan events with radiation included at each step and compare the resulting cross sections as a function of the pair's transverse momentum with the latest LHC measurements.