Second class currents and mirror beta decays

Abstract

Answers are given to some questions raised by Lipkin concerning the relation between mirror asymmetry in beta-decay and second-class currents. Mirror asymmetry (not of electromagnetic origin) is eridenee for second-class currents even taking into account possible CP violation. A non-vanishing mirror asymmetry can be calculated in terms of single-nucleon transition matrices but there is no unique relation between the mirror asymmetry and the matrix elements of the second-class current for free nucleons.

Orbital electron capture by the nucleus

“…Hence, the determination of f is con-T nected with the very question of the existence of second-class currents in 0 decay and electron capture. 11 Although this problem has been dis cussed extensively in the literature (Wilkinson, 1970a#1971, 1972a/72, 19741gAlburger and Wilkinson,, 1970Kim, 1971;Holstein and Treiman, 1971;Vatai, 1971Wilkinson and Alburger, 1971Blomquist, 1971;Wolfenstein and Henley, 1971;Lipkin, 1970Lipkin, , 1971Kim and Fulton, 1971;Blin-Stoyle et al, 1971;Laverne and Dang, 1971;Alburger, 1972;Tzibble and Garvey, 1974;Towner, 1973;Greenland, 1975) an unanbiguous answer concerning the existence of second-class currents has not yet been obtained. An excellent review of this matter has been written by Wilkinson (1971/72).…”