QCDNUM: Fast QCD Evolution and Convolution

TL;DR

QCDNUM is a versatile software tool that efficiently solves QCD evolution equations for parton densities and computes related cross-sections, supporting advanced perturbative orders and various schemes.

Contribution

It introduces a fast, flexible program capable of evolving parton densities up to NNLO and computing structure functions with multiple schemes, enhancing computational efficiency in QCD analyses.

Findings

Supports NNLO evolution for unpolarised densities

Enables evolution of polarised densities and fragmentation functions

Includes tools for calculating structure functions and heavy flavour contributions

Abstract

The QCDNUM program numerically solves the evolution equations for parton densities and fragmentation functions in perturbative QCD. Un-polarised parton densities can be evolved up to next-to-next-to-leading order in powers of the strong coupling constant, while polarised densities or fragmentation functions can be evolved up to next-to-leading order. Other types of evolution can be accessed by feeding alternative sets of evolution kernels into the program. A versatile convolution engine provides tools to compute parton luminosities, cross-sections in hadron-hadron scattering, and deep inelastic structure functions in the zero-mass scheme or in generalised mass schemes. Input to these calculations are either the QCDNUM evolved densities, or those read in from an external parton density repository. Included in the software distribution are packages to calculate zero-mass structure functions in un-polarised deep inelastic scattering, and heavy flavour contributions to these structure functions in the fixed flavour number scheme.