Limiting Behavior of a Class of Hermitian-Yang-Mills Metrics, I

This paper begins to study the limiting behavior of a family of Hermitian Yang-Mills (HYM for brevity) metrics on a class of rank two slope stable vector bundles over a product of two elliptic curves with K\"ahler metrics $\omega_\epsilon$ when $\epsilon\to 0$. Here $\omega_\epsilon$ are flat and have areas $\epsilon$ and $\epsilon^{-1}$ on the two elliptic curves respectively. A family of Hermitian metrics on the vector bundle are explicitly constructed and with respect to them, the HYM metrics are normalized. We then compare the family of normalized HYM metrics with the family of constructed Hermitian metrics by doing estimates. We get the higher order estimates as long as the $C^0$-estimate is provided. We also get the estimate of the lower bound of the $C^0$-norm. If the desired estimate of the upper bound of the $C^0$-norm can be obtained, then it would be shown that these two families of metrics are close to arbitrary order in $\epsilon$ in any $C^k$ norms.