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20102026
most citedA generalization of Ramanujan's congruence to modular forms of prime level

8 citations · 31 across the 33 of their papers we have counts for

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math.NT2026

A decomposition of Weyl group multiple Dirichlet series for symmetrizable Kac-Moody root systems

Alexandru A. Popa, Jack Walsh

We study twisted Weyl group multiple Dirichlet series attached to symmetrizable Kac-Moody root systems, using the Chinta-Gunnells method to construct their -parts. Our main resu…

math.NT2023

Residues of quadratic Weyl group multiple Dirichlet series

Adrian Diaconu, Bogdan Ion, Vicenţiu Paşol +1

We give explicit formulas for the residue of the Chinta-Gunnells average attached to a finite irreducible root system, at the polar divisor corresponding to a simple short root. Th…

math.NT2023

A trace formula for Hecke operators on Fuchsian groups

Alexandru A. Popa

In this paper we give a trace formula for Hecke operators acting on the cohomology of a Fuchsian group of finite covolume, with coefficients in a module . The proof is based on…

math.NT2021

Quadratic Weyl group multiple Dirichlet series of Type

Adrian Diaconu, Vicenţiu Paşol, Alexandru A. Popa

In this paper and its sequel \cite{DPP}, we investigate the precise relationship between the quadratic affine Weyl group multiple Dirichlet series in the sense of \cite{CG1, BD}, a…

math.NT2017★ 4 cited

A simple proof of the Eichler-Selberg trace formula

Alexandru A. Popa, Don Zagier

We give a short proof of the trace formula for Hecke operators on modular forms for the modular group, using the action of Hecke operators on the space of period polynomials.

math.NT2017

On the trace formula for Hecke operators on congruence subgroups, II

Alexandru A. Popa

In a previous paper, we obtained a general trace formula for double coset operators acting on modular forms for congruence subgroups, expressed as a sum over conjugacy classes. Her…

math.NT2016★ 8 cited

A generalization of Ramanujan's congruence to modular forms of prime level

Radu Gaba, Alexandru A. Popa

We prove congruences between cuspidal newforms and Eisenstein series of prime level, which generalize Ramanujan's congruence. Such congruences were recently found by Billerey and M…

math.NT2016★ 1 cited

A combinatorial refinement of the Kronecker-Hurwitz class number relation

Alexandru A. Popa, Don Zagier

We give a refinement of the Kronecker-Hurwitz class number relation, based on a tesselation of the Euclidean plane into semi-infinite triangles labeled by that…

math.NT2014

On the trace formula for Hecke operators on congruence subgroups

Alexandru A. Popa

We give a new, simple proof of the trace formula for Hecke operators on modular forms for finite index subgroups of the modular group. The proof uses algebraic properties of certai…

math.NT2013

Pair correlation of hyperbolic lattice angles

Florin P. Boca, Alexandru A. Popa, Alexandru Zaharescu

Let be a point in the upper half plane, and let be a discrete, finite covolume subgroup of . We conjecture an explicit formula for the pair corr…

math.NT2012

An algebraic property of Hecke operators and two indefinite theta series

Vicentiu Pasol, Alexandru A. Popa

We prove an algebraic property of the elements defining Hecke operators on period polynomials associated with modular forms, which implies that the pairing on period polynomials co…

math.NT2012

On the Petersson scalar product of arbitrary modular forms

Vicentiu Pasol, Alexandru A. Popa

We consider a natural extension of the Petersson scalar product to the entire space of modular forms of integral weight for a finite index subgroup of the modular group. W…

math.NT2011★ 6 cited

Pair correlation of angles between reciprocal geodesics on the modular surface

Florin P. Boca, Vicentiu Pasol, Alexandru A. Popa +1

The existence of the limiting pair correlation for angles between reciprocal geodesics on the modular surface is established. An explicit formula is provided, which captures geomet…