MuonConverter

The main purpose of MuonConverter is to provide an interface between external EFT software such as wilson (https://wilson-eft.github.io/), DsixTools (https://dsixtools.github.io/), etc, and Mu2e_NRET. This interface extends the functionality of the original Mu2e_NRET code and allows for full top-down (or bottom-up) phenomenological studies of muon-to-electron conversion in the field of a target nucleus. Explicitly, in conjunction with external EFT software, MuonConverter can be used to compute the influence of UV charged-lepton-flavor-violating operators on the predictions for branching and capture ratios reported by experimental collaborations.

Both versions of MuonConverter (Python and Mathematica) are comprised of four modular components:

• Numerical inputs --- all numerical inputs are stored within an associative array that can be modified by the user upon intialization of the MuonConverter class. The parameters and their default values can be found in parameters.py(.wl).
• Form factors --- the form factor expressions required for the WET to NRET matching and whose numerical values are derived in App. D can be found in form_factors.py(.wl). For maximum flexibility, the default form factor values may be manually overwritten within parameters.py(.wl).
• Matching --- to facilitate the WET to NRET matching, MuonConverter utilizes derived matching expressions for the relativistic $d_i$ coefficients (the $d_i$ coefficients are automatically translated to the nonrelativistic $c_i$, $b_i$ coefficients within Mu2e_NRET). The matching expressions, as well as their translation to the isospin basis, can be found in hadronization.py(.wl).
• Interfacing --- given an array of WET coefficients (in units of 1/GeV^2), the interface with Mu2e_NRET, utilizing external and internal basis translations as well as the matching expressions implemented in hadronization.py(.wl), can be found in MuonConverter.py(.wl).

See the respecitve example notebooks within the desired language directory for usage examples - including interfacing with external codes.

Dependencies

The Python version of the software was developed in Python 3.10 - a detailed list of software requirements/dependencies can be found in requirements.txt.

If using conda, the environment can be cloned via the command

conda create --name <env> --file requirements.txt

where <env> is the desired environment name.

The Mathematica version of the software was developed in Mathematica 14.0.