Sparse Distribution of Coefficients of $\ell$-fold Product $L$-functions at Integers Represented by Quadratic Forms

Anubhav Sharma, Mohit Tripathi, Lalit Vaishya

Let $f\in S_k({\Gamma }_0(N))$ be a normalized Hecke eigenform. We study the Fourier coefficients ${\lambda }_{f\otimes \cdots {\otimes }_{\ell }f}(n)$ of the $\ell$-fold product $L$-function fo…