Superallowed transitions are -transitions between two members of an isospin multiplet --- for instance a hadron A of spin zero decaying into another spinless hadron with the same parity. In this particular case, the axial vector contribution to the matrix element vanishes because since there is no spin, it is impossible to construct an axial vector out of two hadron momenta alone. These types of transitions are pure vector interactions known as Fermi transitions and can be used to test the CVC hypothesis. The coupling constant is the same as given in equation (). In addition, the matrix element which is known as for pure Fermi transitions, can be evaluated without reference to the details of the nuclear wavefunctions. Since both states belong to the same isomultiplet differing only in their values of (see equation (1.59)), is the matrix element of the isospin raising or lowering operator :

From angular momentum theory,

For all superallowed transitions of the type

and

Mon Jan 15 14:57:06 MET 1996