QCDLoop

QCDLoop
Name	QCDLoop
Developer	Unknown
Released	Unknown
Latest release	Unknown
Programming language	C++
Operating system	Cross-platform
Genre	Scientific software
License	Unknown

QCDLoop QCDLoop is a software library for computing one-loop scalar integrals and related functions used in perturbative calculations in high-energy physics. It interfaces with matrix-element generators and numerical integrators employed at facilities like European Organization for Nuclear Research, Fermi National Accelerator Laboratory, and Lawrence Berkeley National Laboratory. The project is used alongside toolchains involving MadGraph, Sherpa, Powheg, and MCFM for precision predictions at colliders such as the Large Hadron Collider and the Tevatron.

Introduction

QCDLoop provides numerical evaluation of scalar integrals that arise in Feynman diagram computations within Quantum Chromodynamics and electroweak corrections for processes studied at CERN, SLAC National Accelerator Laboratory, and DESY. The library is designed to be embedded into analysis stacks built with frameworks like ROOT, GEANT4, LHAPDF, and HEPMC. QCDLoop complements symbolic reduction engines such as FORM, Mathematica, and FeynCalc used by collaborations including ATLAS, CMS, LHCb, and experimental groups at Brookhaven National Laboratory.

Features and Functionality

QCDLoop implements evaluation routines for scalar one-loop integrals including tadpoles, bubbles, triangles, and boxes that appear in calculations from projects like NNLOJET and MCFM. It supports regularization schemes relevant to workflows at CERN and DESY, and it outputs values compatible with renormalization prescriptions used by researchers associated with Institute for Advanced Study and Perimeter Institute. The library exposes interfaces to pass kinematic invariants, masses, and complex deformation parameters suitable for applications tied to Top quark studies, Higgs boson phenomenology, and exclusive processes examined at Brookhaven National Laboratory.

Implementation and Algorithms

Internally, QCDLoop relies on algorithms for analytic continuation, series expansions, and numerical contour deformation similar to methods used in packages developed at Max Planck Institute for Physics and Institut de Physique Théorique. It uses adaptive precision arithmetic and branch-cut handling techniques analogous to routines in QD and multiprecision libraries used by groups at Los Alamos National Laboratory and Tokyo Institute of Technology. The implementation leverages optimization patterns common in scientific computing projects from Oak Ridge National Laboratory and uses unit tests styled after continuous-integration workflows practiced at Google and Microsoft Research labs collaborating with academic teams.

Usage and Interfaces

QCDLoop provides C++ APIs suitable for integration into event generators like MadGraph and Sherpa and into analysis chains that include ROOT and HEPMC. Bindings or wrappers enable coupling to higher-level systems such as Python-based frameworks used by groups at Princeton University and Massachusetts Institute of Technology. Build systems and packaging mirror approaches from CMake-based projects common at University of California, Berkeley and deployment practices used by consortia like HDF Group and Spack favored by HPC centers including Argonne National Laboratory.

Performance and Validation

Benchmarking of QCDLoop employs test suites derived from reference calculations by collaborations at CERN and theoretical results published through institutions like Institut de Physique Théorique and Perimeter Institute. Performance comparisons reference alternative libraries and tools developed at SLAC National Accelerator Laboratory and Brookhaven National Laboratory, and validation uses sample amplitudes from studies associated with ATLAS and CMS analyses. Profiling for throughput and numerical stability follows methodologies used by software teams at Oak Ridge National Laboratory and National Energy Research Scientific Computing Center.

History and Development

Development of QCDLoop is part of a lineage of loop-integral projects influenced by earlier work from groups at CERN, DESY, and SLAC National Accelerator Laboratory that produced libraries accompanying analytic tools like FormCalc and numerical packages used by LEP and HERA collaborations. Contributions and bug reports have typically flowed through collaborations involving universities such as University of Oxford, University of Cambridge, Harvard University, and national labs including Fermi National Accelerator Laboratory and Brookhaven National Laboratory. Release cycles and maintenance practices reflect community norms established during large-scale projects at European Organization for Nuclear Research.

Applications and Examples

QCDLoop is applied in precision cross-section computations for processes relevant to Higgs boson measurements, Top quark pair production, and electroweak corrections in searches run by ATLAS and CMS. Example workflows embed QCDLoop within matrix-element computations linked to event generators like MadGraph and resummation frameworks from groups at CEA Saclay and DESY. Case studies include comparisons against results from analytic calculations published by teams at IHEP, Max Planck Institute for Physics, and collaborative analyses presented at conferences such as ICHEP and Moriond.

Category:Computational physics