MoCaNLO: a Monte Carlo integrator for NLO calculations

TL;DR

MoCaNLO provides a robust Monte Carlo framework for NLO calculations at hadron colliders, integrating multi-channel phase-space sampling with Recola-generated matrix elements and Catani–Seymour dipole subtraction to yield IR-finite cross sections and distributions. It supports full off-shell effects, spin correlations, and pole-approximation techniques for resonances, enabling accurate treatment of complex final states and vector-boson processes. The manual details a comprehensive workflow: from installation and run-card proc-card parameterization to sequential and averaged runs, pole-approximation options, and advanced features such as polarization, photon isolation, UPCs, and final-state merging. A rich set of input cards and auxiliary tools facilitates flexible channel management, scale variation, and post-processing (plots and k-factors), making MoCaNLO a versatile tool for precision predictions in high-energy phenomenology. The approach has been applied to cutting-edge NLO QCD and EW corrections, demonstrating its viability for high-multiplicity final states and demanding collider processes.

Abstract

We present the Monte Carlo integration code MoCaNLO, which computes cross sections and distributions for processes at high-energy colliders like the LHC at leading and next-to-leading order (NLO) in the strong and electroweak couplings. It relies on the Recola package for the calculation of matrix elements and uses Catani-Seymour dipole subtraction for the treatment of infrared singularities. It has been used for several cutting-edge calculations of NLO QCD and electroweak corrections over the last years, such as NLO QCD corrections to off-shell top-antitop-quark production in association with a pair of bottom quarks and NLO electroweak corrections to vector-boson scattering processes.