
An improved calculation of the isospinsymmetrybreaking corrections to superallowed Fermi beta decayDOI: 10.1103/PhysRevC.77.025501 Abstract: We report new shellmodel calculations of the isospinsymmetrybreaking correction to superallowed nuclear beta decay. The most important improvement is the inclusion of core orbitals, which are demonstrated to have a significant impact on the mismatch in the radial wave functions of the parent and daughter states. We determine which core orbitals are important to include from an examination of measured spectroscopic factors in singlenucleon pickup reactions. We also examine the new radiativecorrection calculation by Marciano and Sirlin and, by a simple reorganization, show that it is possible to preserve the conventional separation into a nucleusindependent inner radiative term and a nucleusdependent outer term. We tabulate new values for the three theoretical corrections for twenty superallowed transitions, including the thirteen wellstudied cases. With these new correction terms the corrected Ft values for the thirteen cases are statistically consistent with one another and the anomalousness of the 46V result disappears. These new calculations lead to a lower average Ft value and a higher value of Vud. The sum of squares of the toprow elements of the CKM matrix now agrees exactly with unitarity.
