VBFNLO: A parton level Monte Carlo for processes with electroweak bosons -- Manual for Version 3.0

TL;DR

VBFNLO 3.0 delivers a versatile, parton-level MC for vector-boson fusion and multi-boson production with NLO QCD, including electroweak corrections to VBF Higgs processes and LO gluon-fusion Higgs production with multiple jets. It introduces BLHA interfacing with BLHA-compatible tools, enhanced unitarisation for dimension-8 operators, and new production channels (e.g., WWjj, ZZjj, γγjj) while adding spin-2 and KK-model capabilities and parallel MPI support. The manual details an extensive input-system (vbfnlo.dat, cuts.dat, ggflo.dat, susy.dat, anomalous-couplings files), process-specific options, and interfacing with Herwig 7, alongside thorough checks and bug-fixes across NLO calculations and event outputs. Collectively, these updates extend the applicability and reliability of VBFNLO for precision predictions and new-physics explorations at the LHC. The practical impact lies in providing a robust, configurable framework for accurate cross sections, differential distributions, and matched/merged simulations across a wide spectrum of SM and BSM scenarios.

Abstract

VBFNLO is a flexible parton level Monte Carlo program for the simulation of vector boson fusion (VBF), QCD-induced single and double vector boson production plus two jets, and double and triple vector boson production (plus jet) in hadronic collisions at next-to-leading order (NLO) in the strong coupling constant, as well as Higgs boson plus two jet production via gluon fusion at the one-loop level. For the new version -- Version 3.0 -- several major enhancements have been included. An interface according to the Binoth Les Houches Accord (BLHA) has been added for all VBF and di/tri-boson processes including fully leptonic decays. For all dimension-8 operators affecting vector boson scattering (VBS) processes, a modified T-matrix unitarization procedure has been implemented. Several new production processes have been added, namely the VBS $Zγjj$ and $γγjj$ processes at NLO, $γγjj $, $WWj$ and $ZZj$ production at NLO including the loop-induced gluon-fusion contributions and the gluon-fusion one-loop induced $Φjjj$ ($Φ$ is a CP-even or CP-odd scalar boson) process at LO, retaining the full top-mass dependence. Finally, the code has been parallelized using OpenMPI.