653 research outputs found
A realization of the Hecke algebra on the space of period functions for Gamma_0(n)
The standard realization of the Hecke algebra on classical holomorphic cusp
forms and the corresponding period polynomials is well known. In this article
we consider a nonstandard realization of the Hecke algebra on Maass cusp forms
for the Hecke congruence subgroups Gamma_0(n). We show that the vector valued
period functions derived recently by Hilgert, Mayer and Movasati as special
eigenfunctions of the transfer operator for Gamma_0(n) are indeed related to
the Maass cusp forms for these groups. This leads also to a simple
interpretation of the ``Hecke like'' operators of these authors in terms of the
aforementioned non standard realization of the Hecke algebra on the space of
vector valued period functions.Comment: 30 pages; corrected typos and fixed incomplete proofs in section
Spectral statistics for quantized skew translations on the torus
We study the spectral statistics for quantized skew translations on the
torus, which are ergodic but not mixing for irrational parameters. It is shown
explicitly that in this case the level--spacing distribution and other common
spectral statistics, like the number variance, do not exist in the
semiclassical limit.Comment: 7 pages. One figure, include
AdS_3 Partition Functions Reconstructed
For pure gravity in AdS_3, Witten has given a recipe for the construction of
holomorphically factorizable partition functions of pure gravity theories with
central charge c=24k. The partition function was found to be a polynomial in
the modular invariant j-function. We show that the partition function can be
obtained instead as a modular sum which has a more physical interpretation as a
sum over geometries. We express both the j-function and its derivative in terms
of such a sum.Comment: 9 page
Bagchi's Theorem for families of automorphic forms
We prove a version of Bagchi's Theorem and of Voronin's Universality Theorem
for family of primitive cusp forms of weight and prime level, and discuss
under which conditions the argument will apply to general reasonable family of
automorphic -functions.Comment: 15 page
Entangled networks, synchronization, and optimal network topology
A new family of graphs, {\it entangled networks}, with optimal properties in
many respects, is introduced. By definition, their topology is such that
optimizes synchronizability for many dynamical processes. These networks are
shown to have an extremely homogeneous structure: degree, node-distance,
betweenness, and loop distributions are all very narrow. Also, they are
characterized by a very interwoven (entangled) structure with short average
distances, large loops, and no well-defined community-structure. This family of
nets exhibits an excellent performance with respect to other flow properties
such as robustness against errors and attacks, minimal first-passage time of
random walks, efficient communication, etc. These remarkable features convert
entangled networks in a useful concept, optimal or almost-optimal in many
senses, and with plenty of potential applications computer science or
neuroscience.Comment: Slightly modified version, as accepted in Phys. Rev. Let
Hierarchy of the Selberg zeta functions
We introduce a Selberg type zeta function of two variables which interpolates
several higher Selberg zeta functions. The analytic continuation, the
functional equation and the determinant expression of this function via the
Laplacian on a Riemann surface are obtained.Comment: 14 page
The second moment of -functions, integrated
We consider the family of Rankin-Selberg convolution L-functions of a fixed
SL(3, Z) Maass form with the family of Hecke-Maass cusp forms on SL(2, Z). We
estimate the second moment of this family of L-functions with a "long"
integration in t-aspect. These L-functions are distinguished by their high
degree (12) and large conductors (of size T^{12}).Comment: v1: 17 pages; v2: 24 pages, improved and expanded expositio
Spectral simplicity and asymptotic separation of variables
We describe a method for comparing the real analytic eigenbranches of two
families of quadratic forms that degenerate as t tends to zero. One of the
families is assumed to be amenable to `separation of variables' and the other
one not. With certain additional assumptions, we show that if the families are
asymptotic at first order as t tends to 0, then the generic spectral simplicity
of the separable family implies that the eigenbranches of the second family are
also generically one-dimensional. As an application, we prove that for the
generic triangle (simplex) in Euclidean space (constant curvature space form)
each eigenspace of the Laplacian is one-dimensional. We also show that for all
but countably many t, the geodesic triangle in the hyperbolic plane with
interior angles 0, t, and t, has simple spectrum.Comment: 53 pages, 2 figure
Monodromy of Cyclic Coverings of the Projective Line
We show that the image of the pure braid group under the monodromy action on
the homology of a cyclic covering of degree d of the projective line is an
arithmetic group provided the number of branch points is sufficiently large
compared to the degree.Comment: 47 pages (to appear in Inventiones Mathematicae
Nodal domains of Maass forms I
This paper deals with some questions that have received a lot of attention
since they were raised by Hejhal and Rackner in their 1992 numerical
computations of Maass forms. We establish sharp upper and lower bounds for the
-restrictions of these forms to certain curves on the modular surface.
These results, together with the Lindelof Hypothesis and known subconvex
-bounds are applied to prove that locally the number of nodal domains
of such a form goes to infinity with its eigenvalue.Comment: To appear in GAF
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