Shifted convolution sums involving theta series

Let f be a cuspidal newform (holomorphic orMaass) of arbitrary level and nebentypus and denote by lambda f (n) its nth Hecke eigenvalue. Let r(n) = # { (n(1),n(2)) is an element of Z(2) : n(1)(2) + n(2)(2) =n } . In this paper, we study the shifted convolution sum S-h(X) = Sigma lambda f(n+h)r(n), 1 <= h <= X, n <= X and establish uniform bounds with respect to the shift h for S-h(X).