Breakdown of Migdal-Eliashberg Theory in Rb${}_3$C${}_{60}$

Abstract

This paper has been withdrawn. An extended version of this work can be found in E. Cappelluti, C. Grimaldi, L. Pietronero, S. Straessler: Phys. Rev. Lett. 85, 4771 (2000) [cond-mat/0105560] and E. Cappelluti, C. Grimaldi, L. Pietronero, S. Straessler, G.A. Ummarino: Eur. Phys. J. B 21, 383 (2001) [cond-mat/0104457]