Isobaric Analog Resonance Widths and the Distribution of Coulomb Mixing Strength in Nuclei

Experimental data on the microgiant spreading widths of analog resonances indicate that these widths decrease slightly with increasing mass number $A$ for $A=37-50\mathrm{}$ and then increase again for $A>\mathrm{}60\mathrm{}$. A calculation is presented in which this remarkable property can be understood in terms of a model in which the distribution of Coulomb mixing strength in a nucleus has two peaks with the analog state lying between these two peaks and moving with respect to them with changes in $A$ and $T_{\zeta }$.