Shake-up and shake-off effects in neutrinoless double-beta decay

TL;DR

This paper investigates the effects of atomic shake-up and shake-off phenomena on neutrinoless double-beta decay, clarifying their impact on decay energy and spectral shape, and proposes experimental verification methods.

Contribution

It clarifies the influence of atomic excitations on decay energy and spectral features, correcting recent misconceptions and suggesting experimental tests.

Findings

Decay Q value is reduced by atomic excitation, not by atomic binding energy differences.

Atomic de-excitation shifts the decay peak back to its nominal value.

Shake-up and shake-off effects impact spectral shapes of double-beta decay.

Abstract

We revisit the role of shake-up and shake-off effects in neutrinoless double-beta decay, following earlier work by Drukarev et al. We find in agreement with Drukarev et al. that the Q value of the decay is reduced by any atomic excitation in the final-state but not by the difference in atomic binding energy of the initial and final state atoms, as was recently suggested by Mei and Wei. We discuss how the absorption of subsequent atomic de-excitation ejecta shifts the neutrinoless double-beta decay peak back to its nominal value. We propose an in situ experimental verification of these ideas, and discuss the impact of shake-up and shake-off on two-neutrino double-beta decay spectral shapes.