Year: 2024
Type: article
Abstract: A bstract We investigate neutrinoless double-beta decay (0 νββ ) in minimal extensions of the Standard Model of particle physics where gauge-singlet right-handed neutrinos give rise to Dirac and Majorana neutrino mass terms. We argue that the standard treatment of these scenarios, based on mass-dependent nuclear matrix elements, is missing important contributions to the 0 νββ amplitude. First, new effects arise from the exchange of neutrinos with very small (ultrasoft) momenta, for which we compute the associated nuclear matrix elements for the decays of 76 Ge and 136 Xe. These contributions can dominate the 0 νββ rate in cases with light sterile neutrinos. The ultrasoft terms are also relevant in the more standard scenario of just three light Majorana neutrinos where they lead to a 10% reduction of the total 0 νββ amplitude. Secondly, we highlight the importance of short-range terms associated with medium-heavy sterile neutrinos and provide explicit formulae that can be used in phenomenological analyses. As examples we discuss impact of these new effects in several explicit scenarios, including a realistic 3 + 2 model with two right-handed gauge-singlet neutrinos.
Source: Journal of High Energy Physics
Authors: W. Dekens, J. de Vries, D. Castillo, J. Menéndez, E. Mereghetti, V. Plakkot, P. Soriano, G. Zhou
Language: English
Topic: Neutrino Physics Research
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: diamond
Awards: G1017065088, INSTITUTE FOR NUCLEAR THEORY, G1217879937, G1279347439, G222768804, G2727898920, INSTITUTE FOR NUCLEAR THEORY, G3035362077, G3196846394, G339957601, G3480869486, G3780874795, G4294200505, G4526231891, G5080475149, G5601966628, The Little Neutral Particle that Could, G6410514744, G6563880843, G7084143925, G7931907585
OpenAlex ID: W4402937678