# Why does the renormalizable theory have only those particles with helicity less than or equal to 1?

Let the helicity operator be $$\frac{P \cdot J}{P^0}$$ with an eigenvalue $$\lambda$$. Then why do renormalizable theories have $$|\lambda| \le 1?$$ (in general dimensions or in 4ds?)

Also, what is the kinetic term of a spin-s particle? For example, for spin-2 particle.

• @G.Smith in p.31 of arXiv:1011.1491v1 – Liberty Mar 27 at 5:07
• Your second question should be posted separately. We have a one-question-per-post rule on this site. Thanks. – G. Smith Mar 27 at 5:08
• @G.Smith i guess the second question is related to the first question by counting the engineering dimensions of the kinetic term. – Liberty Mar 27 at 5:09