On the importance of the 1-loop finite corrections to seesaw neutrino masses

TL;DR

Finite 1-loop corrections in the seesaw mechanism can significantly alter neutrino mass predictions, affecting model parameter scans and mixing patterns, especially for the mixing angle θ₁₃.

Contribution

This paper provides a detailed analysis of finite 1-loop corrections to neutrino masses in the seesaw model, highlighting their potential size and impact on neutrino mixing.

Findings

Corrections can exceed tree-level masses in some cases.

Finite corrections significantly affect the tribimaximal mixing pattern.

Large corrections necessitate their inclusion in parameter space analyses.

Abstract

In the standard seesaw mechanism, finite corrections to the neutrino mass matrix arise from 1-loop self-energy diagrams mediated by a heavy neutrino. We study in detail these corrections and demonstrate that they can be very significant, exceeding in several cases the tree-level result. We consider the normal and inverted hierarchy spectra for light neutrinos and compute the finite corrections to the different elements of the neutrino mass matrix. Special attention is paid to their dependence with the parameters of the seesaw model. Among the cases in which the corrections can be large, we identify the fine-tuned models considered previously in the literature, where a strong cancellation between the different parameters is required to achieve compatibility with the experimental data. As a particular example, we also analyze how these corrections modify the tribimaximal mixing pattern and find that the deviations may be sizable, in particular for $\theta_{13}$. Finally, we emphasize that due to their large size, the finite corrections to neutrino masses have to be taken into account if one wants to properly scan the parameter space of seesaw models.