Hypersharp Neutrino Lines

TL;DR

This paper discusses hypersharp neutrino lines from long-lived nuclei in crystals, which can be used to probe quantum gravity effects by setting limits on the Planck length through resonant neutrino capture.

Contribution

It introduces a frequency modulation approach to derive the hypersharp line fraction, enabling the use of neutrino lines to test quantum gravity models.

Findings

Hypersharp neutrino lines with extremely narrow widths can be produced in crystals.

Resonant capture of neutrinos can be achieved with geometrical cross sections.

Limits on quantum gravity models can be set by measuring neutrino line widths.

Abstract

Neutrino lines from very long lived nuclei in simple crystals such as metals have hypersharp natural width, motionally narrowed by lattice vibrations in analogy to recoilless emission. A generalized hypersharp line fraction including the recoilless part can be derived in a frequency modulation approach. The nue lines of natural width in 3H to 3He 2-body beta-decay can then be resonantly captured with geometrical cross section. The extreme sharpness DeltaE/E~10-29 of the tritium nue line can probe the Planck length L via its limits on the widths of states, DeltaE/E(L) =L(L/R)beta =10-20(beta ~1) to 10-40 (beta= L/R(fm)). Stringent limits can be set on beta, thus, on models of quantum gravity.