On a deformation theory of finite dimensional modules over repetitive algebras

Let $Lambda$ be a basic finite dimensional algebra over an algebraically closed field $mathbf{k}$, and let $widehat{Lambda}$ be the repetitive algebra of $Lambda$. In this article, we prove that if $widehat{V}$ is a left $widehat{Lambda}$-module with finite dimension over $mathbf{k}$, then $widehat{V}$ has a well-defined versal deformation ring $R(widehat{Lambda},widehat{V})$, which is a local complete Noetherian commutative $mathbf{k}$-algebra whose residue field is also isomorphic to $mathbf{k}$. We also prove that $R(widehat{Lambda},widehat{V})$ is universal provided that $underline{mathrm{End}}_{widehat{Lambda}}(widehat{V})=mathbf{k}$ and that in this situation, $R(widehat{Lambda},widehat{V})$ is stable after taking syzygies. We apply the obtained results to finite dimensional modules over the repetitive algebra of the $2$-Kronecker algebra, which provides an alternative approach to the deformation theory of objects in the bounded derived category of coherent sheaves over $mathbb{P}^1_{mathbf{k}}$