Renormalization factor of four fermi operators with clover fermion and   Iwasaki gauge action
  Renormalization factors of four-quark operators are perturbatively calculated for the improved Wilson fermion with clover term and the Iwasaki gauge action. A main application shall be the $K\to\pi\pi$ decay amplitude and the calculation is restricted to the parity odd operator, for which the operators are multiplicatively renormalizable without mixing with wrong operators that have different chiral structures. 
Yusuke Taniguchi
hep-lat