Our aim is to introduce vector mesons in terms of a Lagrangian which satisfies the low energy current algebra. One consistent method is in terms of a non-linear chiral Lagrangian with a hidden local symmetry [6]. In this theory the vector mesons emerge as dynamical vector mesons. The three point vector-pseudo scalar interaction is given by (11)ih4〈Vμ(P∂μP−∂μPP)〉, where h stands for the vector-pseudoscalar coupling. Some typical vertices of ρ's to pseudoscalar mesons are (12)π+(p1)π−(p2)ρ0:h(p1−p2)μεμ,π+(p1)π0(p2)ρ−:h(p1−p2)μεμ,K+(p1)K¯0(p2)ρ−:h2(p1−p2)μεμ,etc., which is directly related to the ρ decay width: Γ(ρ)=h2(|pπ|)3/(6πmρ2), where pπ is the momentum of final state pions in the ρ rest frame. With Γ(ρ)=149.2MeV, we find h=5.95. We note in passing that the Kawarabayashi–Suzuki–Riazuddin–Fayyazuddin relation gives the value h=mρ/(2fπ)[12]. Thus the value of h in Eq. (4) and the two values in this paragraph differ by small amounts (∼19%). The strong four-point vertices involving pions are obtained from the first two terms of Eq. (5). The weak vertices are obtained from the definitions of Q6 and Q8. In the numerical work we shall use the value of h from Eq. (4) and also h=5.95 obtained from the decay width.
