Chiral Perturbation Theory : pi0 pi0 Z vertex?  by Hepth Tags:
chiral, perturbation, theory, vertex Hepth is offline Dec3-12,
11:59 AM PF Gold Hepth's Avatar P: 434 Not sure if anyone has
any experience with chiral perturbation theory, but I'm trying
to see what all of the vertices are for interactions with a
single Z boson. I've looked at the lagrangian up to order p^4 so
far, and it seems that the Z only interacts with charged
pions/kaons. I'm using the external field method. Is there a
reason why these don't appear? I imagine that I have the generic
Z current: \sum_{q = u,d,s} \bar{q} \left( c_L \gamma^{\mu} P_L
+ c_R \gamma^{\mu} P_R\right) q \cdot Z_{\mu} where the
constants are calculable, but it should be noted that due to
weak isospin and charge, the down and strange currents are the
same constant, with the up being different.  I imagine this then
correlates to chiral perturbation theory as an external field
matrix where these constants lie along the diagonal for the left
and right handed external fie