Determine the absolute scale of the neutrino mass

Determine the absolute scale of the neutrino mass by establishing the absolute values of the neutrino mass eigenstates, which cannot be inferred from oscillation experiments that only constrain differences of squared masses.

Background

Neutrino oscillation experiments demonstrate that neutrinos are massive and measure only the differences of the squared masses of the three neutrino mass eigenstates. These measurements do not provide the absolute values of the masses, leaving the overall mass scale undetermined.

This paper contributes an independently measured and highly precise Q-value for electron capture in 163Ho using Penning-trap mass spectrometry, an input needed for calorimetric experiments (ECHo, HOLMES) that aim to directly determine or constrain the electron neutrino mass at the sub-eV level. Addressing the absolute mass scale requires such precision inputs to evaluate systematic uncertainties and enable robust mass extraction.