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
Optimization of generator coordinate method with machine-learning techniques for nuclear spectra and neutrinoless double-beta decay: ridge regression for nuclei with axial deformation
Addendum to: QRPA uncertainties and their correlations in the analysis of neutrinoless double beta decay
在以前的文章[Phys. Rev. D 79，053001（2009）]中，我们在准粒子无规相位近似（QRPA）中估计了与无中微子双β衰变（0 nu β β）的核矩阵元（NME）相关的不确定性。这种估计包括最近对NME的独立计算，因此仍然可以提供核模型不确定性的公平代表。在这种情况下，我们比较了Ge-76中0 nu β β衰变的声明与最近在Ge-136和其他核中的负结果，并推断了在90% C. L.时允许或排除的寿命范围。我们还强调了一些问题，应加以解决，以适当地比较和结合来自不同的0 nu β β衰变候选核的结果。
Systematic study of nuclear matrix elements in neutrinoless double-beta decay with a beyond mean-field covariant density functional theory
本文采用超平均场协变密度泛函理论对无中微子双β衰变中的核矩阵元进行了系统的研究。采用投影和生成坐标方法，考虑了初始核和末态核的粒子数守恒、角动量守恒和四极形状涨落的动力学效应。采用完全相对论跃迁算符计算NME。目前的系统研究表明，在大多数情况下，与Song等人[Phys. Rev. C 90，054309（2014）]中发现的核$^{150}$ Nd相比，与先前基于Gogny力的非相对论计算的一致性要好得多。特别是，我们发现，总的NME可以很好地近似的纯轴向矢量耦合项与相当大的减少计算工作量。
Global Ab initio Neutrino Mass Limits from Neutrinoless Double-Beta Decay
TRIUMF；University of British Columbia（不列颠哥伦比亚大学）；Technische Universität Darmstadt（达姆施塔特工业大学）；GSI Helmholtzzentrum für Schwerionenforschung GmbH（GSI亥姆霍兹重离子研究中心有限公司）；Massachusetts Institute of Technology（麻省理工学院）；McGill University（麦吉尔大学）
