Flavor $\mathrm{SU}\left(3\right)\mathrm{}$ symmetry breaking in hyperon semileptonic decay form factors is analyzed using the ${1/N}_c$ expansion. A detailed comparison with experimental data shows that corrections to $f_1$ are approximately 10%, which agrees with theoretical expectations. Corrections to $g_1$ are compatible with first-order symmetry breaking. A fit to the experimental data allows one to predict the $g_1$ form factor for ${\Xi }^0\to {\Sigma }^{+}$ decay. The proton matrix element of the $T^8$ component of the axial vector current [which is equal to $3F-D$ in the $\mathrm{SU}\left(3\right)\mathrm{}$ symmetry limit] is found to be $\approx 0.34–\mathrm{0.46.}$

• Received 26 May 1998

DOI:https://doi.org/10.1103/PhysRevD.58.094028