An explanation is offered for the large difference in $B\left(E1\mathrm{}\right)\mathrm{}$ values of mirror transitions from ${\mathrm{½}}^{+}$ state to the ground state, based on the difference in binding energy of the ${\mathrm{½}}^{+}$ states. The binding energy determines the degree of coupling of the positive parity nucleon to the deformed ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ core, which in turn affects the $B\left(E1\mathrm{}\right)\mathrm{}$ value. The experimental asymmetry can be satisfied with a small change of the wave function.

• Received 8 September 1975

DOI:https://doi.org/10.1103/PhysRevLett.35.1546