Matching of U_L(3) x U_R(3) and SU_L(3) x SU_R(3) Chiral Perturbation   Theories
  The heavy singlet field is integrated out from the U_L(3) x U_R(3) Chiral Perturbation Theory and it is shown how its effects on the low-energy dynamics are reduced to effective vertices for the light mesons. The results are matched against the standard SU_L(3) x SU_R(3) Chiral Perturbation Theory in order to establish the relations between the coupling constants from both theories to one-loop level accuracy. 
P. Herrera-Sikl\'ody