How Accurate is the Quantum String Bethe Ansatz?
  We compare solutions of the quantum string Bethe equations with explicit one-loop calculations in the sigma-model on AdS(5)xS(5). The Bethe ansatz exactly reproduces the spectrum of infinitely long strings. When the length is finite, we find that deviations from the exact answer arise which are exponentially small in the string length. 
Sakura Schafer-Nameki, Marija Zamaklar, Konstantin Zarembo