# A question in QFT of Weinberg

1. Dec 11, 2013

### ndung200790

In any theory,the propagator $\Delta$$_{f}$(k) of a field of type f has asymptotic behavior:

$\Delta$$_{f}$(k)~k$^{-2+2sf}$

where sf is ''spin'' of the field.For massive fields of Lorentz type (A,B) then sf=A+B.
(However,dropping terms that because of gauge invariance have no effect,eg. photon has sf=0)
(QFT of Weinberg Vol 1,&12.1 Degrees of Divergence)

2. Dec 12, 2013

### ndung200790

I know this is true for photon,W-Z boson,gluon,graviton,spin 1/2 fermion.But what about the other particles?