BMN operators with vector impurities, ℤ2 symmetry and pp-waves

We calculate the coefficients of three-point functions of BMN operators with two vector impurities. We find that these coefficients can be obtained from those of the three-point functions of scalar BMN operators by interchanging the coefficient for the symmetric-traceless representation with the coefficient for the singlet. We conclude that the ℤ ² symmetry of the pp-wave string theory is not manifest at the level of field theory three-point correlators. © SISSA/ISAS 2003.