# How can I see the projection $\pi:H^1(X,\mathcal{O}_X)\rightarrow Pic^{0}(X)$ in terms of holomorphic structures on $X\times\mathbb{C}$?

Hi, as the title says I'm looking for a way to see the projection $\pi:H^1(X,\mathcal{O}_X)\rightarrow \operatorname{Pic}^{0}(X)$ in terms of holomorphic structures on $X\times\mathbb{C}$. ($X$ is a compact complex manifold and $\operatorname{Pic}^0(X)$ is the kernel of $c_1:H^1(X,\mathcal{O}_X^{ * })\rightarrow H^2(X,\mathbb{Z})$ in the long exact sequence induced by the exponential sequence). Since $$H^1(X,\mathcal{O}_X) \simeq H_{\overline{\partial}}^{0,1}$$ by the Dolbeault isomorphism, I take $[c]\in H^1(X,\mathcal{O}_X)$, so I take the corresponding $[\gamma]\in H_{\overline{\partial}}^{0,1}$ and a representative $\gamma$ of the class $[\gamma]$. My wrong thought was that $\pi([c])=(X\times\mathbb{C},\overline{\partial}+\gamma)$, i.e. to associate to $[c]$ the trivial bundle with the "holomorphic structure" $\overline{\partial}+\gamma$, but it is not a holomorphic structure unless $\gamma\wedge\gamma=0$! So how can I see explicitly (if it is possible) the map $\pi$ in terms of holomorphic structures on the trivial line bundle?

• I couldn't read the question before. Now that I can, I will point out that $\gamma\wedge \gamma$ is zero (it's a $1$-form). So your initial idea should work. – Donu Arapura Aug 25 '10 at 12:13