Andreev Bound States in the Kondo Quantum Dots Coupled to   Superconducting Leads
  We have studied the Kondo quantum dot coupled to two superconducting leads and investigated the subgap Andreev states using the NRG method. Contrary to the recent NCA results [Clerk and Ambegaokar, Phys. Rev. B 61, 9109 (2000); Sellier et al., Phys. Rev. B 72, 174502 (2005)], we observe Andreev states both below and above the Fermi level. 
Jong Soo Lim and Mahn-Soo Choi