A1 Journal article (refereed)
Confirmation of gA quenching using the revised spectrum-shape method for the analysis of the 113Cd β-decay as measured with the COBRA demonstrator (2021)

Kostensalo, J., Suhonen, J., Volkmer, J., Zatschler, S., & Zuber, K. (2021). Confirmation of gA quenching using the revised spectrum-shape method for the analysis of the 113Cd β-decay as measured with the COBRA demonstrator. Physics Letters B, 822, Article 136652. https://doi.org/10.1016/j.physletb.2021.136652

JYU authors or editors

Publication details

All authors or editors: Kostensalo, Joel; Suhonen, Jouni; Volkmer, Juliane; Zatschler, Stefan; Zuber, Kai

Journal or series: Physics Letters B

ISSN: 0370-2693

eISSN: 1873-2445

Publication year: 2021

Volume: 822

Article number: 136652

Publisher: Elsevier

Publication country: Netherlands

Publication language: English

DOI: https://doi.org/10.1016/j.physletb.2021.136652

Publication open access: Openly available

Publication channel open access: Open Access channel

Publication is parallel published (JYX): https://jyx.jyu.fi/handle/123456789/77944

Web address of parallel published publication (pre-print): https://arxiv.org/abs/2011.11061


In this article we present an updated spectrum-shape analysis of the113Cd fourfold forbidden non-uniqueβ-decay transition in order to address the quenching of the weak axial-vector coupling gA in low-momentum exchange nuclear processes. The experimental data were collected in a dedicated low-threshold run with the COBRA demonstrator at the LNGS and resulted in 44 individual113Cdspectra. These data are evaluated in the context of three nuclear model frameworks based on a revised version of the spectrum-shape method and the conserved vector current hypothesis. The novel idea devised in the present work is to fit the value of the small relativistic nuclear matrix element (s-NME) driving the nuclear model calculations, which remained essentially as a free parameter in previous studies. This is done by tuning the nuclear structure calculations and making use of the interplay of gA and the s-NME such that the experimentally known113Cd half-life gets reproducible by the different frameworks. In this way, a best fit s-NME value can be derived for each of the considered nuclear models, which finally enters the template calculations used to perform the spectrum-shape analysis for each of the obtained113Cd spectra. The primary analysis strategy results in significantly quenched values of the axial-vector coupling for all three nuclear models: gA(ISM)=0.907±0.064,gA(MQPM)=0.993±0.063andgA(IBFM-2)=0.828±0.140. Moreover, with our data-driven approach one of the main shortcomings of the spectrum-shape method has been resolved. This achievement is a milestone in the description of strongly forbiddenβ-decays and adds to the indications for the existence of a quenching of gA in low-momentum exchange nuclear processes.

Keywords: nuclear physics

Free keywords: 113Cd β-decay; axial-vector coupling; gA quenching; spectrum-shape method; CdZnTe; COBRA

Contributing organizations

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Ministry reporting: Yes

Reporting Year: 2021

JUFO rating: 2

Last updated on 2022-20-09 at 15:22