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We study the argument of L(s, f) associated with holomorphic cusp form in both weight aspect and t-aspect. We prove that for −1 ≤ σ ≤ 2 and t ≥ 4, argL(s, f) ≪ log kt, where s = σ + it. Assuming the generalized Riemann hypothesis (GRH), we have arg L(s, f) ≪ log kt/log log kt for σ ≥ 1/2 and t ≥ 4.

Let f(z) be a primitive holomorphic cusp form of even integral weight k for the full modular group. Denote its nth normalized Fourier coefficient (Hecke eigenvalue) by λf (n). Let a(n) be the function with squarefull kernel. In this paper, we establish that $$ {\sum}_{n\leqslant x}a(n){\lambda}_f^2\left(n+1\right)= Cx+O\left({x}^{13/14+\upepsilon}\right) $$, where C is a constant that can be explicitly evaluated.

We obtain a discrete universality theorem on the approximation of analytic functions by shifts of L-functions of normalized Hecke-eigen cusp forms with respect to congruence subgroups. Such a result is already proved in the authors’ previous paper [A. Lauriňcikas, K. Matsumoto, and J. Steuding, Discrete universality of L-functions for new forms, Math. Notes, 78(4):551–558, 2005] under a certain arithmetical condition, which we remove in this paper. Also, we present discrete analogues of results of [A. Lauriňcikas, K. Matsumoto, and J. Steuding, Universality of some functions related to zeta-functions of certain cusp forms, Osaka J. Math., 50(4):1021–1037, 2013].

Let f be a fixed holomorphic Hecke eigen cusp form of weight k for \( SL\left( {2,{\mathbb Z}} \right) \), and let \( {\mathcal U} = \left\{ {{u_j}:j \geqslant 1} \right\} \) be an orthonormal basis of Hecke–Maass cusp forms for \( SL\left( {2,{\mathbb Z}} \right) \). We prove an asymptotic formula for the twisted first moment of the Rankin–Selberg L-functions \( L\left( {s,f \otimes {u_j}} \right) \) at \( s = \frac{1}{2} \) as uj runs over \( {\mathcal U} \). It follows that f is uniquely determined by the central values of the family of Rankin–Selberg L-functions \( \left\{ {L\left( {s,f \otimes {u_j}} \right):{u_j} \in {\mathcal U}} \right\} \).

We obtain a limit theorem for the modulus of the argument of zeta-functions near the critical line of normalized eigenforms.

We improve the existing upper bound for the quantity |∑ n⩽x a(n 2)|, where a(n 2) is the n 2th Hecke eigenvalue of a normalized holomorphic cusp form (Hecke eigenform) of the full modular group SL(2, ℤ), whenever the weight of the original holomorphic cusp form (Hecke eigenform) lies in a certain range.