AUTHOR=Suzuki Toshio , Shimizu Noritaka 

TITLE=Shell-model study of weak β-decays relevant to astrophysical processes

JOURNAL=Frontiers in Physics

VOLUME=12

YEAR=2024

URL=https://www.frontiersin.org/journals/physics/articles/10.3389/fphy.2024.1434598

DOI=10.3389/fphy.2024.1434598

ISSN=2296-424X

ABSTRACT=<p>Shell-model studies on the weak <inline-formula id="inf2"><mml:math id="m2" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>β</mml:mi></mml:math></inline-formula>-decay in nuclei relevant to astrophysical processes are carried out. The <inline-formula id="inf3"><mml:math id="m3" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>β</mml:mi></mml:math></inline-formula>-decay rates, as well as electron-capture rates in the <inline-formula id="inf4"><mml:math id="m4" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>s</mml:mi><mml:mi>d</mml:mi></mml:math></inline-formula>-<inline-formula id="inf5"><mml:math id="m5" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>p</mml:mi><mml:mi>f</mml:mi></mml:math></inline-formula> shell induced by Gamow–Teller (GT) transition, are evaluated in astrophysical environments. The weak rates for the Urca pair of nuclei with <inline-formula id="inf6"><mml:math id="m6" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>A</mml:mi></mml:math></inline-formula> = 31 in the island of inversion, which are important for the nuclear Urca processes in neutron star crusts, are investigated by shell-model calculations in the <inline-formula id="inf7"><mml:math id="m7" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>s</mml:mi><mml:mi>d</mml:mi></mml:math></inline-formula>–<inline-formula id="inf8"><mml:math id="m8" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>p</mml:mi><mml:mi>f</mml:mi></mml:math></inline-formula> shell. The GT strength is evaluated in the <inline-formula id="inf9"><mml:math id="m9" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>s</mml:mi><mml:mi>d</mml:mi></mml:math></inline-formula>–<inline-formula id="inf10"><mml:math id="m10" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>p</mml:mi><mml:mi>f</mml:mi></mml:math></inline-formula> shell for selected <inline-formula id="inf11"><mml:math id="m11" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>β</mml:mi></mml:math></inline-formula>-decays in the <inline-formula id="inf12"><mml:math id="m12" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>s</mml:mi><mml:mi>d</mml:mi></mml:math></inline-formula>-shell nuclei, and the effects of the expansion of the configuration space on the quenching of the axial–vector coupling are examined. <inline-formula id="inf13"><mml:math id="m13" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>β</mml:mi></mml:math></inline-formula>-decay rates induced by first-forbidden (FF) transitions are studied by the Behrens–Bühring (BB) method for the isotones with <inline-formula id="inf15"><mml:math id="m15" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>N</mml:mi></mml:math></inline-formula> = 126 and compared with the Walecka method. The important role of the electron distortions in the <inline-formula id="inf16"><mml:math id="m16" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>β</mml:mi></mml:math></inline-formula>-decays of <sup>206</sup>Hg and <sup>207</sup>Tl is pointed out.</p>