- #1

- 83

- 1

[tex] \dfrac{- (pq) p^{2}}{-pq \pm \sqrt{(pq)^{2} - p^{2} q^{2}}} [/tex].

with q --> 0, but I don't know how to do that.

p and q are two four-vectors, so we have: [tex] pq = p_{\mu} q^{\mu} [/tex] and so on.

Does anyone have an idea? Or at least: Is it somehow possible to "simplify" or rewrite the expression in the limit q --> 0 ?