Caravel: A C++ Framework for the Computation of Multi-Loop Amplitudes with Numerical Unitarity

TL;DR

Caravel is a new C++17 framework that enables the numerical computation of multi-loop scattering amplitudes in quantum field theory, integrating integrand decomposition, tree-level calculations, and amplitude evaluation.

Contribution

It introduces the first public version of Caravel, a comprehensive framework for multi-loop amplitude calculations using the numerical unitarity method in quantum field theory.

Findings

Successfully computes selected one- and two-loop amplitudes in QCD and gravity.

Provides modular tools for integrand decomposition and functional reconstruction.

Demonstrates main functionalities through example programs.

Abstract

We present the first public version of Caravel, a C++17 framework for the computation of multi-loop scattering amplitudes in quantum field theory, based on the numerical unitarity method. Caravel is composed of modules for the $D$-dimensional decomposition of integrands of scattering amplitudes into master and surface terms, the computation of tree-level amplitudes in floating point or finite-field arithmetic, the numerical computation of one- and two-loop amplitudes in QCD and Einstein gravity, and functional reconstruction tools. We provide programs that showcase Caravel's main functionalities and allow to compute selected one- and two-loop amplitudes.