Eur. Phys. J. C (2015) 75: 27
https://doi.org/10.1140/epjc/s10052-014-3249-9

Special Article - Tools for Experiment and Theory

CHIRON: a package for ChPT numerical results at two loops

Department of Astronomy and Theoretical Physics, Lund University, Sölvegatan 14A, 223-62, Lund, Sweden

^* e-mail: bijnens@thep.lu.se

Received: 3 December 2014
Accepted: 22 December 2014
Published online: 24 January 2015

Abstract

This document describes the package CHIRON which includes two libraries, chiron itself and jbnumlib. chiron is a set of routines useful for two-loop numerical results in chiral perturbation theory (ChPT). It includes programs for the needed one- and two-loop integrals as well as routines to deal with the ChPT parameters. The present version includes everything needed for the masses, decay constants and quark-antiquark vacuum-expectation-values. An added routine calculates consistent values for the masses and decay constants when the pion and kaon masses are varied. In addition a number of finite volume results are included: one-loop tadpole integrals, two-loop sunset integrals and the results for masses and decay constants. The numerical routine library jbnumlib contains the numerical routines used in chiron. Many are to a large extent simple C++ versions of routines in the CERNLIB numerical library. Notable exceptions are the dilogarithm and the Jacobi theta function implementations. This paper describes what is included in CHIRON v0.50.