Yrast band in the heavy $N = Z$ nucleus $^{88}$Ru: $alpha$-cluster approach

The yrast band in the heavy $N = Z$ nucleus $^{88}$Ru is studied in the framework of the $alpha$-cluster model in combination with double-folding potentials. It is found that the excitation energies of the yrast band in $^{88}$Ru can be nicely described within the $alpha$-cluster approach using a smooth and mildly $L$-dependent adjustment of the potential strength. This result is similar to well-established $alpha$-cluster states in nuclei with a (magic core $otimes$ $alpha$) structure. Contrary, the yrast bands in neighboring $N e Z$ nuclei deviate from such a typical $alpha$-cluster behavior. Finally, the $alpha$-cluster model predicts reduced transition strengths of about 10 Weisskopf units for intraband transitions between low-lying states in the yrast band of $^{88}$Ru.