Implementation of SANC EW corrections in WINHAC Monte Carlo generator

TL;DR

The paper validates the implementation of SANC one-loop electroweak corrections in the WINHAC Monte Carlo generator for charged-current Drell–Yan W production. Using a tuned comparison framework with YFS-based initial-state radiation subtraction and two EW schemes ($\alpha(0)$ and $G_\mu$), the authors demonstrate sub-per-mill agreement between WINHAC and the SANC integrator for both inclusive cross sections and key differential distributions at LO and NLO. They also quantify purely weak corrections and lepton-mass effects, finding excellent electron-channel agreement and small mass-related biases in the muon channel. These results establish WINHAC as a precise tool for LHC W-boson physics with EW corrections and provide a benchmark for other generators, with future work extending to neutral-current DY (ZINHAC).

Abstract

In this paper we describe a check of the implementation of SANC system generated modules into the framework of the WINHAC Monte Carlo event generator. At this stage of work we limit ourselves to inclusion of complete one-loop electroweak corrections to the charged-current Drell--Yan process. We perform tuned comparisons of the results derived with the aid of two codes: 1) the standard SANC integrator with YFS-inspired treatment of the ISR QED corrections and 2) the WINHAC generator, upgraded with the SANC electroweak modules and downgraded to the O(α) QED corrections. The aim of these comparisons is to prove the correctness of implementation of the SANC electroweak modules into the WINHAC generator. This is achieved through the presented tuned comparisons.

Figures (15)

• Figure 1: The Born distributions of $M_{\rm T}^{\rm W}$ from SANC (red diamonds) and WINHAC (solid lines) in two schemes and their relative deviations $\delta=\frac{{\rm W}-{\rm S}}{{\rm W}}.$
• Figure 2: The Born distributions of $p_{\rm T}^{\ell}$ from SANC (red diamonds) and WINHAC (solid lines) in two schemes and their relative deviations $\delta=\frac{{\rm W}-{\rm S}}{{\rm W}}.$
• Figure 3: The Born distributions of $|\eta_\ell|$ from SANC (red diamonds) and WINHAC (solid lines) in two schemes and their relative deviations $\delta=\frac{{\rm W}-{\rm S}}{{\rm W}}.$
• Figure 4: The EW NLO distributions of $M_{\rm T}^{\rm W}$ from SANC (red diamonds) and WINHAC (solid lines) for the electron channel in two schemes and their absolute deviations $\Delta={{\rm W}-{\rm S}}$.
• Figure 5: The EW NLO distributions of $p_{\rm T}^{\ell}$ from SANC (red diamonds) and WINHAC (solid lines) for the electron channel in two schemes and their absolute deviations $\Delta={{\rm W}-{\rm S}}$.