Determine the absolute neutrino mass scale

Determine the absolute mass scale of neutrinos, i.e., the overall magnitude of neutrino masses independent of mixing and ordering, which remains unresolved in particle physics and for which neutrinoless double-beta decay half-life measurements could provide critical insights.

Background

The paper motivates neutrinoless double-beta decay searches by emphasizing their potential to reveal whether neutrinos are Majorana particles and to inform the absolute neutrino mass scale. While upper limits on the decay half-life have improved, translating such limits into constraints on the effective Majorana mass is hindered by theoretical uncertainties in nuclear matrix elements.

The authors’ measurement of the 4th-forbidden β-decay of 115In and the associated study of g_A quenching aim to improve nuclear modeling relevant to double-beta decay. Such advances are expected to reduce uncertainties that currently complicate the extraction of neutrino mass information from experimental half-life measurements.

References

The half-life of this process ($T{0\nu}_{1/2}$) could provide insights into the absolute mass scale of neutrinos, which is still an unsolved issue in particle physics.

— Simultaneous Measurement of Half-Life and Spectral Shape of $^{115}$In $β$-decay with an Indium Iodide Cryogenic Calorimeter  (2401.16059 - Pagnanini et al., 2024) in Introduction, first paragraph (p. 1)

In oscillation experiments merely the differences of the squared neutrino mass eigenvalues can be investigated, leaving the absolute scale of the neutrino mass an open question.

— Penning-trap measurement of the $Q$-value of the electron capture in $^{163}\mathrm{Ho}$ for the determination of the electron neutrino mass  (2402.06464 - Schweiger et al., 2024) in Section 1, The absolute scale of the neutrino mass