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Consider a Symplectic manifold D (with $H^1(D)=0$) with symplectic form $w$. Let V be the total space of a circle bundle over D with non-trivial Euler class $e\in H^2(D)$. You may think of V as the set of unit vectors in a complex line L bundle over D with chern class e. Then we can construct a symplectic form ,denote it by same symbol $w$, on total space of L whose restriction to D is the original w. The question is whether V has a contact structure with a contact form $\alpha$ such that $d\alpha=w\mid_V$.

Looking the the Gysinn sequence : $0\rightarrow H^0(D) \rightarrow H^2(D) \rightarrow H^2(V) \rightarrow 0$ it seems that the answer is:

Yes iff $w$ is multiple of e.

I Just wanted to make sure that my conclusion is correct!

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# Contact structure on a circle bundle over a symplectic manifold.

Consider a Symplectic manifold D (with $H^1(D)=0$) with symplectic form $w$. Let V be the total space of a circle bundle over D with Euler class $e\in H^2(D)$. You may think of V as the set of unit vectors in a complex line L bundle over D with chern class e. Then we can construct a symplectic form ,denote it by same symbol $w$, on total space of L whose restriction to D is the original w. The question is whether V has a contact structure with a contact form $\alpha$ such that $d\alpha=w\mid_V$.

Looking the the Gysinn sequence : $0\rightarrow H^0(D) \rightarrow H^2(D) \rightarrow H^2(V) \rightarrow 0$ it seems that the answer is:

Yes iff $w$ is multiple of e.

I Just wanted to make sure that my conclusion is correct!