Ternary Quadratic Forms And Half-Integral Weight Modular Forms

Abstract

Let $k$ be a positive integer such that $k\equiv 3\mathrm{mod}4$, and let $N$ be a positive square-free integer. In this paper, we compute a basis for the two-dimensional subspace $S_{\frac{k}{2}}({\Gamma }_0(4N),F)$ of half-integral weight modular forms associated, via the Shimura correspondence, to a newform $F\in S_{k-1}({\Gamma }_0(N))$, which satisfies $L(F,\frac{1}{2})\ne 0$. This is accomplished by using a result of Waldspurger, which allows one to produce a basis for the forms that correspond to a given $F$ via local considerations, once a form in the Kohnen space has been determined

arXiv comment20 pages