[Paper Review] Vbfnlo: A parton level Monte Carlo for processes with electroweak bosons - Manual for Version 2.5.0

K. Arnold, Johannes Bellm+22 more|arXiv (Cornell University)|Jul 20, 2011

Particle physics theoretical and experimental studiesPhysics and Astronomy78 references50 citations

TL;DR

Vbfnlo v2.5.0 is a parton-level Monte Carlo generator for NLO QCD and electroweak corrections in vector boson fusion, vector boson pair and triple production, and Higgs boson production via gluon fusion. It extends capabilities to include new processes like Higgs+photon, triboson production, MSSM, anomalous couplings, and the Three-Site Higgsless model, with improved Higgs signal modeling and electroweak corrections.

ABSTRACT

Vbfnlo is a flexible parton level Monte Carlo program for the simulation of vector boson fusion, double and triple vector boson production 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. In the new release – Version 2.5.0 – several new processes have been added at NLO QCD: vector boson fusion production of a Higgs boson plus a photon, vector boson fusion production of a photon, Wγ and WZ production plus a hadronic jet and the triboson production processes WWγ,ZZγ,WZγ,Wγγ,Zγγ and γγγ. The code has been extended to run in the Minimal Supersymmetric Standard Model (MSSM), and electroweak corrections to Higgs boson production via weak boson fusion have been included. Anomalous gauge boson couplings can be used in new processes and the Three-Site Higgsless model has been implemented for several processes. The simulation of Higgs boson production via gluon fusion has been improved.

Motivation & Objective

• To extend the Vbfnlo framework to include new NLO QCD processes involving electroweak bosons and photons.
• To enable simulation of Higgs boson production via gluon fusion at one-loop level with improved accuracy.
• To incorporate electroweak corrections into Higgs boson production via weak boson fusion.
• To support phenomenological studies in the Minimal Supersymmetric Standard Model (MSSM) and models with anomalous gauge couplings.
• To implement the Three-Site Higgsless model for selected processes to explore alternative Higgs sector scenarios.

Proposed method

• The program employs next-to-leading-order (NLO) QCD calculations to compute scattering amplitudes for multi-boson final states in hadronic collisions.
• It uses a fully automated implementation of the FKS subtraction method to handle infrared and collinear divergences in NLO calculations.
• Matrix elements are computed using helicity amplitude techniques and optimized for numerical stability across phase space.
• The code integrates electroweak corrections via effective field theory and loop-induced contributions for Higgs production in vector boson fusion.
• It supports model extensions such as the MSSM and anomalous gauge boson couplings through flexible parameterization of vertices.
• The Three-Site Higgsless model is implemented via modified gauge boson propagators and vertex structures in selected processes.

Experimental results

Research questions

• RQ1 How can NLO QCD corrections be efficiently and accurately simulated for vector boson fusion processes involving photons and multiple bosons?
• RQ2 What improvements are needed in Higgs boson production via gluon fusion to match current LHC precision measurements?
• RQ3 To what extent can electroweak corrections in weak boson fusion Higgs production affect signal observables?
• RQ4 How well can Vbfnlo model new triboson processes like WWγ and Zγγ at NLO QCD?
• RQ5 What are the phenomenological implications of including the Three-Site Higgsless model in vector boson fusion and diboson production?

Key findings

• The Vbfnlo v2.5.0 release includes new NLO QCD processes such as vector boson fusion with a Higgs boson and photon, and triboson production involving photons and weak bosons.
• Electroweak corrections have been successfully incorporated into Higgs boson production via weak boson fusion, enhancing theoretical precision.
• The program now supports simulations in the Minimal Supersymmetric Standard Model (MSSM), enabling phenomenological studies beyond the Standard Model.
• Anomalous gauge boson couplings are implemented for new processes, allowing direct comparison with LHC data on rare vector boson interactions.
• The Three-Site Higgsless model has been implemented for several processes, providing a tool for testing Higgsless scenarios.
• Improvements to Higgs boson production via gluon fusion include better handling of one-loop matrix elements and enhanced numerical stability.