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

• Main Authors: Isabel Campos, Patrick Fritzsch, Martin Hansen, Marina Krstic Marinkovic, Agostino Patella, Alberto Ramos, Nazario Tantalo
• Format: Article
• Language: English
• Published: SpringerOpen 2020-03-01
• Series: European Physical Journal C: Particles and Fields
• Online Access: http://link.springer.com/article/10.1140/epjc/s10052-020-7617-3

Abstract We present the open-source package openQ* D-1.0 (openQ*D. GitLab: https://gitlab.com/rcstar/openQxD. CSIC: https://dx.doi.org/10.20350/digitalCSIC/8591. https://hdl.handle.net/10261/173334, 2019), which has been primarily, but not uniquely, designed to perform lattice simulations of QCD+QED and QCD, with and without $$\mathrm {C}^*$$ C∗ boundary conditions, and O(a) improved Wilson fermions. The use of $$\mathrm {C}^*$$ 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 (Simulation program for lattice QCD (openQCD code). https://cern.ch/luscher/openQCD, 2016) and NSPT-1.4 (Numerical Stochastic Perturbation Theory (NSPT code). https://cern.ch/luscher/NSPT, 2017). 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.