# Equivariant integration (localization formula)

We consider the action of $S^{1}$ on $S^{2}$ by rotation respect the vertical axes. We want to integrate the $2-$ equivariant form

$$\alpha(X)= -X\cos(\phi) +\sin(\phi)\,d\phi\,d\theta.$$

We have the localization formula: $$\int_{S^{2}} \alpha(X)= (-2\pi)^{\ell} \sum_{p \in M_{0}(X)} \frac{\alpha(X)(p)}{\det(L_{p})^{1/2}}$$

(where $\ell=\dim(M)/2$, $\alpha(X)(p)$ the value of the function $\alpha(X)_{[0]}$ in the point $p$, $M_{0}(X)$ is the set of zeros of $X$ and for $p \in M_{0}(X)$ $L_{p}$ is a linear automorphism of $T_{p}(M)$ induced by the Lie action $L(X)\xi = [X, \xi]$ ). So we consider $X \in Lie(S^{1})= \mathbb{R}$. How can I explicity integrate this form ($\int_{S^{2}}\alpha(X)$)? (I know that the result is $2 \pi$)

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Your question might be more appropriate for math.stackexchange.com, but as is I can't read it. Could you fix your typesetting? – Ryan Budney Feb 1 '13 at 1:25
It's really mysterious to me why MathOverflow isn't typesetting that correctly; the LaTeX is proper. – Allen Knutson Feb 1 '13 at 3:06
Perhaps it could use some well placed backticks around the math environments? – Ricardo Andrade Feb 1 '13 at 3:50
Score! (But why suggest this, rather than trying it? And why upvote it, rather than trying it?) – Allen Knutson Feb 1 '13 at 16:18
He might not have enough "reputation" to edit someone else's question. – Peter Samuelson Feb 1 '13 at 21:19