Title | Long-Distance Nuclear Matrix Elements for Neutrinoless Double-Beta Decay from Lattice QCD |

Publication Type | Journal Article |

Year of Publication | 2024 |

Authors | Davoudi, Z, Detmold, W, Fu, Z, Grebe, AV, Jay, W, Murphy, D, Oare, P, Shanahan, PE, Wagman, ML |

Date Published | 2/14/2024 |

Abstract | Neutrinoless double-beta (0νββ) decay is a heretofore unobserved process which, if observed, would imply that neutrinos are Majorana particles. Interpretations of the stringent experimental constraints on 0νββ-decay half-lives require calculations of nuclear matrix elements. This work presents the first lattice quantum-chromodynamics (LQCD) calculation of the matrix element for 0νββ decay in a multi-nucleon system, specifically the nn→ppee transition, mediated by a light left-handed Majorana neutrino propagating over nuclear-scale distances. This calculation is performed with quark masses corresponding to a pion mass of mπ=806 MeV at a single lattice spacing and volume. The statistically cleaner Σ−→Σ+ee transition is also computed in order to investigate various systematic uncertainties. The prospects for matching the results of LQCD calculations onto a nuclear effective field theory to determine a leading-order low-energy constant relevant for 0νββ decay with a light Majorana neutrino are investigated. This work, therefore, sets the stage for future calculations at physical values of the quark masses that, combined with effective field theory and nuclear many-body studies, will provide controlled theoretical inputs to experimental searches of 0νββ decay. |

URL | https://arxiv.org/abs/2402.09362 |