CRunDec is "a C++ program for the running and decoupling of the strong coupling constant and quark masses", developed by Florian Herren and Matthias Steinhauser. Relevant references:

• "Version 3 of RunDec and CRunDec", Florian Herren, Matthias Steinhauser arXiv:1703.03751
• "CRunDec: a C++ package for running and decoupling of the strong coupling and quark masses", Barbara Schmidt, Matthias Steinhauser arXiv:1201.6149
• "RunDec: A Mathematica package for running and decoupling of the strong coupling and quark masses", K.G. Chetyrkin, Johann H. Kühn, M. Steinhauser arXiv:hep-ph/0004189

Source code of CRunDec 3.1

rundec-python is a Python package providing a thin wrapper around CRunDec.

pip install rundec

The API is analogous to CRunDec, see the documentation.

import rundec

crd = rundec.CRunDec()

# compute alpha_s at the b quark mass scale with 3-loop accuracy
crd.AlphasExact(0.1185, 91.1876, 4.18, 5, 3)

# compute the b quark pole mass using the 4-loop conversion from the MSbar mass without charm mass effects
crd.mMS2mOS(4.18, None,  0.26, 4.18, 5, 4)

# compute the b quark pole mass using the 4-loop conversion from the MSbar mass with finite charm mass effects
mq = rundec.RunDecPairArray(4)
mcMS = rundec.RunDecPair()
mcMS.first  = 0.993
mcMS.second = 3.
mq[0] = mcMS
crd.mMS2mOS(4.18, mq,  0.26, 4.18, 5, 4)

# compute the b quark kinetic mass using the 3-loop conversion from the MSbar mass
mcMS = rundec.RunDecPair()
mcMS.first  = 0.993
mcMS.second = 3.
crd.mMS2mKIN(4.163, mcMS,  0.225, 4.163, 1, 3, 1)

The wrapper was generated with SWIG.

Binary wheels are provided via PyPI for Linux, macOS, and Windows (built with GitHub Actions).

Python 3.10+ is supported.