$^{28}$Al Half-life Measurement and the negative mirror asymmetry between the $^{28}$Al($\beta^-$)$^{28m}$Si and $^{28}$P($\beta^+$)$^{28m}$Si decays

B. Liu; M. Brodeur; D. W. Bardayan; F. D. Becchetti; C. Boomershine; D. P. Burdette; L. Caves; O. Olivas-Gomez; S. L. Henderson; J. J. Kolata; J. Long; A. D. Nelson; P. D. O'Malley; A. Pardo; R. Zite

arXiv · 2505.01722

$^{28}$Al Half-life Measurement and the negative mirror asymmetry between the $^{28}$Al($\beta^-$)$^{28m}$Si and $^{28}$P($\beta^+$)$^{28m}$Si decays

B. Liu·M. Brodeur·D. W. Bardayan·F. D. Becchetti·C. Boomershine·D. P. Burdette·L. Caves·O. Olivas-Gomez·S. L. Henderson·J. J. Kolata·J. Long·A. D. Nelson·P. D. O'Malley·A. Pardo·R. Zite

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Abstract

In the past, the mirror asymmetry parameter has been proposed as a probing mechanism for the presence of beyond the Standard Model second-class currents in nuclear beta decay transitions. However, this was hindered by large uncertainties in the required nuclear structure correction terms. Recently, a new calculation of these corrections attempted, but could not fully explain the negative mirror asymmetry between the $^{28}$Al($\beta^-$)$^{28m}$Si and $^{28}$P($\beta^+$)$^{28m}$Si decays. To put the mirror asymmetry parameter on a more solid footing, the half-life of $^{28}$Al was measured for the first time using a radioactive ion beam at the Nuclear Science Laboratory of the University of Notre Dame. The new result, $t_{1/2}=$134.432(34) s, is consistent with most of the past data except for one highly discrepant measurement. The new mirror asymmetry parameter of -3.5(10)$\%$ obtained still does not agree with nuclear structure calculations.

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B. Liu, M. Brodeur, D. W. Bardayan, F. D. Becchetti, C. Boomershine, D. P. Burdette, L. Caves, O. Olivas-Gomez, S. L. Henderson, J. J. Kolata, J. Long, A. D. Nelson, P. D. O'Malley, A. Pardo, R. Zite. 2025-05-03. $^{28}$Al Half-life Measurement and the negative mirror asymmetry between the $^{28}$Al($\beta^-$)$^{28m}$Si and $^{28}$P($\beta^+$)$^{28m}$Si decays. https://arxiv.org/abs/2505.01722

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