The power of neutrino mass sum rules for neutrinoless double beta decay experiments

Abstract

Neutrino mass sum rules relate the three neutrino masses within generic classes of flavour models, leading to restrictions on the effective mass parameter measured in experiments on neutrinoless double beta decay as a function of the lightest neutrino mass. We perform a comprehensive study of the implications of such neutrino mass sum rules, which provide a link between model building, phenomenology, and experiments. After a careful explanation of how to derive predictions from sum rules, we discuss a large number of examples both numerically, using all three global fits available for the neutrino oscillation data, and analytically wherever possible. In some cases, our results disagree with some of those in the literature for reasons that we explain. Finally we discuss the experimental prospects for many current and near-future experiments, with a particular focus on the uncertainties induced by the unknown nuclear physics involved. We find that, in many cases, the power of the neutrino mass sum rules is so strong as to allow certain classes of models to be tested by the next generation of neutrinoless double beta decay experiments.

A model of quark and lepton mixing

“…If the lightest neutrino mass were artificially increased by an order of magnitude to m 1 = 3 meV, and the other parameters unchanged, we would find |m ee | ≈ 2.4 meV. This demonstrates the insensitivity of |m ee | to the lightest neutrino mass and shows that, although significant cancellations could in principle occur in the calculation of |m ee | for a normal hierarchy [53], for the predicted PMNS parameters of the tetra-model such cancellations do not occur. 5 If we were to set m1 = 0 and choose the opposite phase η = −2π/5 then we would find the results presented previously in [12], namely θ l 12 ≈ 34…”

A White Paper on keV sterile neutrino Dark Matter

“…The basic problem is that the reservoir of possible symmetries is practically unlimited; for any possible observed pattern of neutrino masses and mixings one could find a symmetry that "predicts" it. In this situation, models can only be convincing if they either predict observables that have not been measured, such as mass [219,[223][224][225][226] or mixing [219,[227][228][229] sum rules, or are "simple" and aesthetically appealing from some viewpoint. Prior to the measurement of θ 13 , models predicting θ 13 = 0 seemed well-motivated, such as those leading to tri/bi-maximal mixing [230][231][232][233][234].…”

Revisiting Minimal Lepton Flavour Violation in the light of leptonic CP violation

“…In the field of discrete flavour models, this indication translated into looking, for the first time, for approaches and/or contexts where, besides the mixing angles, also the lepton phase(s) were predicted: new models were presented with the CP symmetry as part of the full flavour symmetry [94][95][96][97][98][99][100]; studies on the mixing patterns and their modifications to provide realistic descriptions of oscillation data were performed [101][102][103][104]; an intense activity was dedicated to investigate sum rules involving neutrino masses, mixing angles and δ CP [102][103][104][105][106][107][108][109].…”