Beta Spectrum Generator: High precision allowed β spectrum shapes

© 2019 Elsevier B.V. Several searches for Beyond Standard Model physics rely on an accurate and highly precise theoretical description of the allowed β spectrum. Following recent theoretical advances, a C++ implementation of an analytical description of the allowed beta spectrum shape was constructed. It implements all known corrections required to give a theoretical description accurate to a few parts in 10 4 . The remaining nuclear structure-sensitive input can optionally be calculated in an extreme single-particle approximation with a variety of nuclear potentials, or obtained through an interface with more state-of-the-art computations. Due to its relevance in modern neutrino physics, the corresponding (anti)neutrino spectra are readily available with appropriate radiative corrections. In the interest of user-friendliness, a graphical interface was developed in Python with a coupling to a variety of nuclear databases. We present several test cases and illustrate potential usage of the code. Our work can be used as the foundation for current and future high-precision experiments related to the beta decay process. Source code: https://github.com/leenderthayen/BSG Documentation: http://bsg.readthedocs.io Program summary: Program Title: BSG Program Files doi: http://dx.doi.org/10.17632/gx6yrpn22x.1 Licensing provisions: MIT Programming language: C++ and Python Nature of problem: The theoretical allowed β spectrum contains a large variety of corrections from different areas of physics, each of which is important in certain energy ranges. A high precision description is required for new physics searches throughout the entire nuclear chart. Solution method: We implement the analytical corrections described in recent theoretical work. Nuclear matrix elements in allowed Gamow–Teller β decay are calculated in a spherical harmonic oscillator basis. Wave functions can be calculated in an extreme single-particle approximation using different nuclear potentials, or provided by the user as the output from more sophisticated routines. Corresponding neutrino spectra are calculated with appropriate radiative corrections. A graphical user interface written in Python additionally provides connections to a variety of nuclear databases. Additional comments: CPC Library subprograms used: ABOV_v1_0status: publishe