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Main Authors: Kishimoto, Tadafumi, Sato, Toru
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2508.18562
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author Kishimoto, Tadafumi
Sato, Toru
author_facet Kishimoto, Tadafumi
Sato, Toru
contents We investigate the residual energy distribution in the electron capture (EC) process of $^{159}$Dy, emphasizing the role of subthreshold atomic states, which have typically been omitted in conventional spectral analyses. By incorporating these energetically forbidden hole states into the spectral function $P(E)$, we demonstrate a significant enhancement - over an order of magnitude - in the EC rate near the zero-momentum neutrino emission region. This enhancement increases further with larger $Q$ values, contrary to standard expectations. Our analysis shows that $P(E)$ can be experimentally determined, resolving ambiguities near the endpoint and enabling new approaches to 'ultra-low $Q$ value' EC reactions for neutrino mass studies.
format Preprint
id arxiv_https___arxiv_org_abs_2508_18562
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Contribution of Subthreshold States to the Residual Energy Distribution of $^{159}$Dy
Kishimoto, Tadafumi
Sato, Toru
Nuclear Theory
High Energy Physics - Phenomenology
Nuclear Experiment
We investigate the residual energy distribution in the electron capture (EC) process of $^{159}$Dy, emphasizing the role of subthreshold atomic states, which have typically been omitted in conventional spectral analyses. By incorporating these energetically forbidden hole states into the spectral function $P(E)$, we demonstrate a significant enhancement - over an order of magnitude - in the EC rate near the zero-momentum neutrino emission region. This enhancement increases further with larger $Q$ values, contrary to standard expectations. Our analysis shows that $P(E)$ can be experimentally determined, resolving ambiguities near the endpoint and enabling new approaches to 'ultra-low $Q$ value' EC reactions for neutrino mass studies.
title Contribution of Subthreshold States to the Residual Energy Distribution of $^{159}$Dy
topic Nuclear Theory
High Energy Physics - Phenomenology
Nuclear Experiment
url https://arxiv.org/abs/2508.18562