Speaker
Description
In this poster, we present an in-depth investigation of the recently found issues in the FxFx matching-merging procedure in MadGraph5_aMC@NLO for usage at the LHC. We compare the predictions for $W+3$ jets and $Z+3$ jets against corresponding measurements from ATLAS and CMS, studying a variety of final-state kinematic distributions and highlighting regions where mismatches are most pronounced. Our analysis includes a systematic survey of different processes and observables, incorporating both parton-level and post-parton-shower (PS) outputs. We also examine the patterns exhibited by, among others, LHE weights, scale variations, jet multiplicities, software versions, and matching algorithms, aiming to identify and quantify the sources of the observed discrepancies. Finally, we present the fixes proposed by one of the FxFx authors, Rikkert Frederix, demonstrating how these modifications can substantially improve consistency between theoretical predictions and experimental data.