193 research outputs found
Congruence Property In Conformal Field Theory
The congruence subgroup property is established for the modular
representations associated to any modular tensor category. This result is used
to prove that the kernel of the representation of the modular group on the
conformal blocks of any rational, C_2-cofinite vertex operator algebra is a
congruence subgroup. In particular, the q-character of each irreducible module
is a modular function on the same congruence subgroup. The Galois symmetry of
the modular representations is obtained and the order of the anomaly for those
modular categories satisfying some integrality conditions is determined.Comment: References are updated. Some typos and grammatical errors are
correcte
From 2-sequents and Linear Nested Sequents to Natural Deduction for Normal Modal Logics
We extend to natural deduction the approach of Linear Nested Sequents and
2-sequents. Formulas are decorated with a spatial coordinate, which allows a
formulation of formal systems in the original spirit of natural
deduction---only one introduction and one elimination rule per connective, no
additional (structural) rule, no explicit reference to the accessibility
relation of the intended Kripke models. We give systems for the normal modal
logics from K to S4. For the intuitionistic versions of the systems, we define
proof reduction, and prove proof normalisation, thus obtaining a syntactical
proof of consistency. For logics K and K4 we use existence predicates
(following Scott) for formulating sound deduction rules
Geometry of Prym semicanonical pencils and an application to cubic threefolds
In the moduli space of double étale covers of curves of a fixed genus , the locus formed by covers of curves with a semicanonical pencil consists of two irreducible divisors and . We study the Prym map on these divisors, which shows significant differences between them and has a rich geometry in the cases of low genus. In particular, the analysis of has enumerative consequences for lines on cubic threefolds
Painlev\'e III and the Hankel Determinant Generated by a Singularly Perturbed Gaussian Weight
In this paper, we study the Hankel determinant generated by a singularly
perturbed Gaussian weight By using the ladder operator approach associated with the orthogonal
polynomials, we show that the logarithmic derivative of the Hankel determinant
satisfies both a non-linear second order difference equation and a non-linear
second order differential equation. The Hankel determinant also admits an
integral representation involving a Painlev\'e III. Furthermore, we consider
the asymptotics of the Hankel determinant under a double scaling, i.e.
and such that is fixed. The
asymptotic expansions of the scaled Hankel determinant for large and small
are established, from which Dyson's constant appears.Comment: 22 page
Random Matrix Models, Double-Time Painlev\'e Equations, and Wireless Relaying
This paper gives an in-depth study of a multiple-antenna wireless
communication scenario in which a weak signal received at an intermediate relay
station is amplified and then forwarded to the final destination. The key
quantity determining system performance is the statistical properties of the
signal-to-noise ratio (SNR) \gamma\ at the destination. Under certain
assumptions on the encoding structure, recent work has characterized the SNR
distribution through its moment generating function, in terms of a certain
Hankel determinant generated via a deformed Laguerre weight. Here, we employ
two different methods to describe the Hankel determinant. First, we make use of
ladder operators satisfied by orthogonal polynomials to give an exact
characterization in terms of a "double-time" Painlev\'e differential equation,
which reduces to Painlev\'e V under certain limits. Second, we employ Dyson's
Coulomb Fluid method to derive a closed form approximation for the Hankel
determinant. The two characterizations are used to derive closed-form
expressions for the cumulants of \gamma, and to compute performance quantities
of engineering interest.Comment: 72 pages, 6 figures; Minor typos corrected; Two additional lemmas
added in Appendix
Fuzzy Scalar Field Theory as a Multitrace Matrix Model
We develop an analytical approach to scalar field theory on the fuzzy sphere
based on considering a perturbative expansion of the kinetic term. This
expansion allows us to integrate out the angular degrees of freedom in the
hermitian matrices encoding the scalar field. The remaining model depends only
on the eigenvalues of the matrices and corresponds to a multitrace hermitian
matrix model. Such a model can be solved by standard techniques as e.g. the
saddle-point approximation. We evaluate the perturbative expansion up to second
order and present the one-cut solution of the saddle-point approximation in the
large N limit. We apply our approach to a model which has been proposed as an
appropriate regularization of scalar field theory on the plane within the
framework of fuzzy geometry.Comment: 1+25 pages, replaced with published version, minor improvement
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