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arXiv · 2111.00696

Weyl-type bounds for twisted $GL(2)$ short character sums

Aritra Ghosh
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Abstract

Let f be a Hecke-Maass or holomorphic primitive cusp form for $SL(2,\mathbb{Z})$ with Fourier coefficients $\lambda_{f}(n)$. Let $\chi$ be a primitive Dirichlet character of modulus p, where p is a prime number. In this article we prove the following Weyl-type bound: for any $\epsilon >0$, $$\sum_{|n| \ll N}\lambda_{f}(n)\chi (n) \ll_{f,\epsilon}N^{3/4 }p^{1/6}(pN)^{\epsilon}.$$ We can see an improvement of the range $N > p^{3/4}$ to the range $N > p^{2/3}$ and we get a bound for $S_{f,\chi}(N)$ without going into the $L$-function.

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Aritra Ghosh. 2021-11-01. Weyl-type bounds for twisted $GL(2)$ short character sums. https://doi.org/10.1007/s11139-022-00664-3

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