Abstract
In view of a recent controversy we investigated the Mott-Hubbard transition in D = ∞ with a novel cluster approach. i) We show that any truncated Bethe lattice of order n can be mapped exactly to a finite, Hubbard-like cluster. ii) We evaluate the self-energy numerically for n = 0, 1, 2 and compare with a series of self-consistent equation-of-motion solutions. iii) We find the gap to open continuously at the critical Uc ∼ 2.5t* (t ≡ t* /√(4d)). iv) A low-energy theory for the Mott-Hubbard transition is developed and relations between critical exponents are presented.