Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. It's 100% free.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

In Steven Weinberg's book "The Quantum Theory of Fields" vol. I, Section 12.1, page 500, it writes:

"We will write the asymptotic behavior of the propagator $\Delta_f(k)$ of a field of type $f$ in the form

$$\Delta_f(k)\sim k^{-2+2s_f}$$

Looking back at Chapter 6, we see that $s_f=0$ for scalar fields, $s_f=\frac{1}{2}$ for Dirac fields, ans $s_f=1$ for massive vector fields. More generally, it can be shown that for massive fields of Lorentz transformation type $(A,B)$, we have $s_f=A+B$. Speaking loosely, we may call $s_f$ the 'spin'."

How can we show that $s_f=A+B$ holds for massive fields of type $(A,B)$? Does anyone have some ideas of the proof? Thanks a lot in advance!

share|cite|improve this question

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Browse other questions tagged or ask your own question.