Effect of first forbidden decays on the shape of neutrino spectra

TL;DR

This paper investigates how First Forbidden decays influence neutrino spectra from beta decay, suggesting they could partly explain the Reactor Neutrino Anomaly, but emphasizes the need for further data and analysis.

Contribution

It provides a microscopic nuclear structure calculation of FF decay branches and explores their impact on neutrino spectra, a novel approach in this context.

Findings

FF decays may contribute to the missing neutrinos in the Reactor Neutrino Anomaly

Analysis of even-even nuclei shows significant FF decay effects

Further research required for definitive conclusions

Abstract

We examine the effect of First Forbidden (FF) decays on $\beta$-decay neutrino spectra by performing microscopic nuclear structure calculations. By analyzing the FF decay branches of even-even nuclei we conclude that FF decays may be responsible for part of the missing neutrinos in the so called "Reactor Neutrino Anomaly". Further calculations and more experimental data are needed for a firm conclusion.