A product formula for period integrals.
Conformal blocks and cohomology in genus 0
We give a characterization of conformal blocks in terms of the singular cohomology of suitable smooth projective varieties, in genus for classical Lie algebras and .
From holonomy of the Ising model form factors to -fold integrals and the theory of elliptic curves.
Galois theory of fuchsian q-difference equations
Gauge-equivalent deformations of linear ordinary differential operators with constant coefficients.
Gauss-Manin systems, Brieskorn lattices and Frobenius structures (I)
We associate to any convenient nondegenerate Laurent polynomial on the complex torus a canonical Frobenius-Saito structure on the base space of its universal unfolding. According to the method of K. Saito (primitive forms) and of M. Saito (good basis of the Gauss-Manin system), the main problem, which is solved in this article, is the analysis of the Gauss-Manin system of (or its universal unfolding) and of the corresponding Hodge theory.
Geometry and analytic theory of Frobenius manifolds.
Hyperelliptic action integral
Applying the “exact WKB method” (cf. Delabaere-Dillinger-Pham) to the stationary one-dimensional Schrödinger equation with polynomial potential, one is led to a multivalued complex action-integral function. This function is a (hyper)elliptic integral; the sheet structure of its Riemann surface above the plane of its values has interesting properties: the projection of its branch-points is in general a dense subset of the plane, and there is a group of symmetries acting on the surface. The distribution...
Localization of global existence of holomorphic solutions of holomorphic differential equations with infinite dimensional parameter
Multiple zeta values and periods of moduli spaces
We prove a conjecture due to Goncharov and Manin which states that the periods of the moduli spaces of Riemann spheres with marked points are multiple zeta values. We do this by introducing a differential algebra of multiple polylogarithms on and proving that it is closed under the operation of taking primitives. The main idea is to apply a version of Stokes’ formula iteratively to reduce each period integral to multiple zeta values. We also give a geometric interpretation of the double shuffle...
On solutions of the KZ and qKZ equations at level zero
Réversibilité et classification des centres nilpotents
Nous considérons un germe de 1-forme analytique dans dont le 1-jet est . Nous montrons que si l’équation définit un centre (i.e toutes les courbes solutions sont des cycles) il existe une involution analytique de préservant le portrait de phase du système. Géométriquement ceci signifie que les centres analytiques nilpotents sont obtenus par image réciproque par des applications pli. Un théorème de conjugaison équivariante permet d’obtenir une classification complète de ces centres.
Sur les représentations de Krammer génériques
Nous définissons une représentation des groupes d’Artin de type par monodromie de systèmes KZ généralisés, dont nous montrons qu’elle est isomorphe à la représentation de Krammer généralisée définie originellement par A.M.Cohen et D.Wales, et indépendamment par F.Digne. Cela implique que tous les groupes d’Artin purs de type sphérique sont résiduellement nilpotents-sans-torsion, donc (bi-)ordonnables. En utilisant cette construction nous montrons que ces représentations irréductibles sont Zariski-denses...
The sympletic nature of the space of projective connections on Riemann surfaces.
Universal isomonodromic deformations of meromorphic rank 2 connections on curves
We consider tracefree meromorphic rank 2 connections over compact Riemann surfaces of arbitrary genus. By deforming the curve, the position of the poles and the connection, we construct the global universal isomonodromic deformation of such a connection. Our construction, which is specific to the tracefree rank 2 case, does not need any Stokes analysis for irregular singularities. It is thereby more elementary than the construction in arbitrary rank due to B. Malgrange and I. Krichever and it includes...
Асимптотическое описание решений четвертого уравнения Пенлеве на аналогах лучей Стокса