Implications of Recent KATRIN Results for Lower-Limits on Neutrino Masses

TL;DR

This paper discusses how recent KATRIN results, combined with astrophysical constraints, could soon fully determine the lower and upper bounds on neutrino masses, including sterile neutrinos, within the next few years.

Contribution

It introduces a novel approach by integrating KATRIN's upper bounds with astrophysical lower bounds to constrain neutrino masses more tightly.

Findings

KATRIN's upper bound on neutrino mass is less than 0.8 eV/c².

Astrophysical considerations imply a lower bound of about 0.4 eV/c² for the smallest neutrino mass.

The combined bounds could potentially exclude all viable parameter space for neutrino masses soon.

Abstract

Recently announced results from the KATRIN collaboration imply an upper bound on the effective electron anti-neutrino mass $m_{\nu_{e}}$, $m_{\nu_{e}}< 0.8~{\rm eV}/c^{2}$. Here we explore the implications of combining the KATRIN upper bound using a previously inferred lower bound on the smallest neutrino mass state, $m_{i,{\rm min}}\gtrsim 0.4~{\rm eV}/c^{2}$ implied by the stability of white dwarfs and neutron stars in the presence of long-range many-body neutrino-exchange forces. By combining a revised lower bound estimate with the expected final upper bound from KATRIN, we find that the available parameter space for $m_{\nu_{e}}$ may be closed completely within the next few years. We then extend the argument when a single light sterile neutrino flavor is present to set a lower mass limit on sterile neutrinos.