4,130 research outputs found
Reconstructing WKB from topological recursion
We prove that the topological recursion reconstructs the WKB expansion of a
quantum curve for all spectral curves whose Newton polygons have no interior
point (and that are smooth as affine curves). This includes nearly all
previously known cases in the literature, and many more; in particular, it
includes many quantum curves of order greater than two. We also explore the
connection between the choice of ordering in the quantization of the spectral
curve and the choice of integration divisor to reconstruct the WKB expansion.Comment: 68 pages, 9 figures. v2: published version (improved presentation
Think globally, compute locally
We introduce a new formulation of the so-called topological recursion, that
is defined globally on a compact Riemann surface. We prove that it is
equivalent to the generalized recursion for spectral curves with arbitrary
ramification. Using this global formulation, we also prove that the correlation
functions constructed from the recursion for curves with arbitrary ramification
can be obtained as suitable limits of correlation functions for curves with
only simple ramification. It then follows that they both satisfy the properties
that were originally proved only for curves with simple ramification.Comment: 37 pages, v2: published versio
Evidences of Interdependence and Contagion using a Frequency Domain Framework
The purpose of this paper is to propose a new measure of contagion. Our approach to testing contagion is based on the frequency analysis of causality developed recently by Breitung and Candelon (2004). This approach handles, in a unified framework, several of the statistical problems identified in the literature. It also permits clear differentiation between temporary and permanent shifts in cross-market linkages: the first case is contagion while the second one is simply a measure of interdependence among markets. In examining the ”Tequila” and Asian crises, we find evidence for contagion during both. It also turns out that during the Asian crisis both contagion and higher interdependence have contributed simultaneously to the diffusion of the crisis in Asia. The spillover effects of these crises have been geographically limited to the region where the shock originated.macroeconomics ;
Critical Gaussian multiplicative chaos: Convergence of the derivative martingale
In this paper, we study Gaussian multiplicative chaos in the critical case.
We show that the so-called derivative martingale, introduced in the context of
branching Brownian motions and branching random walks, converges almost surely
(in all dimensions) to a random measure with full support. We also show that
the limiting measure has no atom. In connection with the derivative martingale,
we write explicit conjectures about the glassy phase of log-correlated Gaussian
potentials and the relation with the asymptotic expansion of the maximum of
log-correlated Gaussian random variables.Comment: Published in at http://dx.doi.org/10.1214/13-AOP890 the Annals of
Probability (http://www.imstat.org/aop/) by the Institute of Mathematical
Statistics (http://www.imstat.org
Log-correlated Gaussian fields: an overview
We survey the properties of the log-correlated Gaussian field (LGF), which is
a centered Gaussian random distribution (generalized function) on , defined up to a global additive constant. Its law is determined by the
covariance formula
which holds for mean-zero test functions . The LGF belongs to
the larger family of fractional Gaussian fields obtained by applying fractional
powers of the Laplacian to a white noise on . It takes the
form . By comparison, the Gaussian free field (GFF)
takes the form in any dimension. The LGFs with coincide with the 2D GFF and its restriction to a line. These objects
arise in the study of conformal field theory and SLE, random surfaces, random
matrices, Liouville quantum gravity, and (when ) finance. Higher
dimensional LGFs appear in models of turbulence and early-universe cosmology.
LGFs are closely related to cascade models and Gaussian branching random walks.
We review LGF approximation schemes, restriction properties, Markov properties,
conformal symmetries, and multiplicative chaos applications.Comment: 24 pages, 2 figure
A non-conservative Harris ergodic theorem
We consider non-conservative positive semigroups and obtain necessary and
sufficient conditions for uniform exponential contraction in weighted total
variation norm. This ensures the existence of Perron eigenelements and provides
quantitative estimates of the spectral gap, complementing Krein-Rutman theorems
and generalizing probabilistic approaches. The proof is based on a
non-homogenous -transform of the semigroup and the construction of Lyapunov
functions for this latter. It exploits then the classical necessary and
sufficient conditions of Harris's theorem for conservative semigroups and
recent techniques developed for the study of absorbed Markov processes. We
apply these results to population dynamics. We obtain exponential convergence
of birth and death processes conditioned on survival to their quasi-stationary
distribution, as well as estimates on exponential relaxation to stationary
profiles in growth-fragmentation PDEs
Real Exchange Rates, Commodity Prices and Structural Factors in Developing Countries
This paper provides new empirical evidence about the relationship that may exist between real exchange rates and commodity prices in developing countries that are specialized in the export of a main primary commodity. It investigates how structural factors like the exchange rate regime, the degree of financial and trade openness, the degree of export concentration and the type of the commodity exports affect the strength of the commodity price-real exchange rate dependence.Real exchange rates, commodity prices, exchange rate regime, financial openness, panel analysis
Real exchanges rates in commodity producing countries : A reappraisal
Commodity currency literature recently stressed the importance of commodity prices as a determinant of real exchange rates in developing countries (Cashin, Cespedes and Sahay 2004). We provide new empirical evidence on this issue by focusing on countries which are specialized in the ex-port of one leading commodity. For those countries, we investigate to which extent their real exchange rate is sensitive to price fluctuations of their dominant commodity. By using non-stationary panel techniques robust to cross-sectional-dependence, we find that the price of the dominant commodity has a significant long-run impact on the real exchange rate when the exports of the leading commodity have a share of at least 20 percent in the country’s total exports of merchandises. Our results also show that the larger the share, the larger the size of the impact.real exchange rates, commodity prices, non-stationary panel
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