Antiferromagnetic Operators in N=4 Supersymmetric Yang-Mills Theory
  The spectrum of operators in the su(2) sector of N=4 SYM is bounded because the number of operators is finite. According to the AdS/CFT correspondence, the string spectrum in this sector should be also bounded. In this paper the upper bound on the scaling dimension is calculated in the limit of the large R-charge using Bethe ansatz. 
K. Zarembo