openQ*D code: a versatile tool for QCD+QED simulations

TL;DR

The paper introduces openQ*D-1.0, an open-source software package for lattice QCD+QED simulations, enabling precise calculations of isospin-breaking and radiative effects with advanced boundary conditions and improved algorithms.

Contribution

It provides a versatile, optimized tool for QCD+QED lattice simulations with C* boundary conditions, enhancing the calculation of hadronic observables from first principles.

Findings

Supports QCD+QED and QCD simulations with various boundary conditions

Inherits advanced features from openQCD-1.6 for efficiency

Enables precise isospin-breaking and radiative correction calculations

Abstract

We present the open-source package openQ*D-1.0, which has been primarily, but not uniquely, designed to perform lattice simulations of QCD+QED and QCD, with and without C* boundary conditions, and O(a) improved Wilson fermions. The use of C* boundary conditions in the spatial direction allows for a local and gauge-invariant formulation of QCD+QED in finite volume, and provides a theoretically clean setup to calculate isospin-breaking and radiative corrections to hadronic observables from first principles. The openQ*D code is based on openQCD-1.6 and NSPT-1.4. In particular it inherits from openQCD-1.6 several core features, e.g. the highly optimized Dirac operator, the locally deflated solver, the frequency splitting for the RHMC, or the 4th order OMF integrator.