Drell-Yan processes with WINHAC
W. Placzek, S. Jadach, M. W. Krasny
TL;DR
WINHAC is a Monte Carlo event generator tailored for Drell–Yan processes across hadron collisions, incorporating multiphoton radiation via YFS exponentiation and O(α) electroweak corrections for charged-current DY, with PHOTOS-based final-state radiation for neutral-current DY and integration with PYTHIA for QCD effects. The work demonstrates that accurate predictions at the LHC require simultaneous treatment of EW corrections and QCD parton-shower effects, particularly for precise W-boson mass measurements. The authors validate WINHAC against independent codes at the per-mille level and showcase applications to MW/ΔMW measurements and to double Drell–Yan processes from DPS, which can impact Higgs searches in ZZ and WW channels. Future directions include developing C++ versions (WINHAC++, ZINHAC) and interfacing with dedicated QCD shower generators to enhance performance and flexibility.
Abstract
We present the Monte Carlo event generator WINHAC for Drell-Yan processes in proton-proton, proton-antiproton, proton-ion and ion-ion collisions. It features multiphoton radiation within the Yennie-Frautschi-Suura exclusive exponentiation scheme with O(alpha) electroweak corrections for the charged-current (W+/W-) processes and multiphoton radiation generated by PHOTOS for neutral-current (Z+gamma) ones. For the initial-state QCD/QED parton shower and hadronisation it is interfaced with PYTHIA. It includes several options, e.g. for the polarized W-boson production, generation of weighted/unweighted events, etc. WINHAC was cross-checked numerically at the per-mille level with independent Monte Carlo programs, such as HORACE and SANC. It has been used as a basic tool for developing and testing some new methods of precise measurements of the Standard Model parameters at the LHC, in particular the W-boson mass. Recently, it has been applied to simulations of double Drell-Yan processes resulting from double-parton scattering, in order to assess their influence on the Higgs-boson detection at the LHC in its ZZ and W+W- decay channels.