Jeudi 10 Décembre 2026, 11:00 à LPTHE, bibliothèque du LPTHE, tour 13-14, 4eme étage	SEM-DARBOUX (Séminaire Darboux - physique théorique et mathématiques)	hep-th
Farrell Brumley ( Sorbonne )	TBA
Abstract:	(basé sur 2604.01075 )

Jeudi 17 Décembre 2026, 10:00 à IHP, Choquet Bruhat	RENC-THEO (Rencontres Théoriciennes)	hep-th
Tba	TBA

Jeudi 17 Décembre 2026, 11:00 à IHES, Amphithéâtre Léon Motchane ( Séminaire de Géométrie Arithmétique )	MATH-IHES (TBA)	math
Kenz Kallal ( Princeton University )	Algebraic Theory of Indefinite Theta Functions
Abstract:	Jacobi's theta function $\Theta(q) := 1 + 2q + 2q^4 + 2q^9 + \cdots $, and more generally the theta functions associated to positive-definite quadratic forms, have the property that they are modular forms of half-integral weight. The usual proof of this fact is completely analytic in nature, using the Poisson summation formula. However, $\Theta$ is also related to diffusion of heat on a uniform circle-shaped material: it is a restriction of the fundamental solution to the heat equation on a circle. By algebraically characterizing the heat equation as a specific flat connection on a certain bundle on a modular curve, we produce a completely algebraic technique for proving modularity of theta functions. More specifically, we produce a refinement of the algebraic theory of theta functions due to Moret-Bailly, Faltings--Chai, and Candelori. As a consequence of the algebraic nature of our theory and the fact that it applies to indefinite quadratic forms / non-ample line bundles (which the prior algebraic theory does not), we also generalize the Kudla--Millson analytic theory of theta functions for indefinite quadratic forms to the case of torsion coefficients. This is joint work with Akshay Venkatesh.

Jeudi 7 Janvier 2027, 10:00 à IHP, Choquet Bruhat	RENC-THEO (Rencontres Théoriciennes)	hep-th
Tba	TBA

Mercredi 13 Janvier 2027, 13:00 à IHP, Amphithéâtre Yvonne Choquet-Bruhat	SEED (Seed Seminar of Mathematics and Physics)	math-ph
Seed Seminar	Kickoff event (13:00-18:00)

Jeudi 21 Janvier 2027, 10:00 à IHP, Choquet Bruhat	RENC-THEO (Rencontres Théoriciennes)	hep-th
Tba	TBA

Mercredi 27 Janvier 2027, 10:30 à IHES, Amphithéâtre Léon Motchane	SEED (Seed Seminar of Mathematics and Physics)	math-ph
Tba	TBA

Mercredi 27 Janvier 2027, 11:45 à IHES, Amphithéâtre Léon Motchane	SEED (Seed Seminar of Mathematics and Physics)	math-ph
Tba	TBA

Jeudi 28 Janvier 2027, 11:00 à LPTHE, bibliothèque du LPTHE, tour 13-14, 4eme étage	SEM-DARBOUX (Séminaire Darboux - physique théorique et mathématiques)	hep-th
Thierry Levy ( IMJ-PRG )	TBA

Jeudi 4 Fevrier 2027, 10:00 à IHP, Choquet Bruhat	RENC-THEO (Rencontres Théoriciennes)	hep-th
Tba	TBA

Mercredi 24 Fevrier 2027, 10:30 à IHES, Amphithéâtre Léon Motchane	SEED (Seed Seminar of Mathematics and Physics)	math-ph
Tba	TBA

Mercredi 24 Fevrier 2027, 11:45 à IHES, Amphithéâtre Léon Motchane	SEED (Seed Seminar of Mathematics and Physics)	math-ph
Tba	TBA

Jeudi 4 Mars 2027, 11:00 à LPTHE, bibliothèque du LPTHE, tour 13-14, 4eme étage	SEM-DARBOUX (Séminaire Darboux - physique théorique et mathématiques)	hep-th|math.PR
Isabelle Gallagher ( U. Paris Cité )	TBA

Jeudi 11 Mars 2027, 10:00 à IHP, Choquet Bruhat	RENC-THEO (Rencontres Théoriciennes)	hep-th
Tba	TBA

Mercredi 24 Mars 2027, 13:00 à IHP, Amphithéâtre Yvonne Choquet-Bruhat	SEED (Seed Seminar of Mathematics and Physics)	math-ph
Seed Seminar	Kickoff event (13:00-18:00)

Jeudi 25 Mars 2027, 10:00 à IHP, Choquet Bruhat	RENC-THEO (Rencontres Théoriciennes)	hep-th
Tba	TBA

Jeudi 1 Avril 2027, 11:00 à LPTHE, bibliothèque du LPTHE, tour 13-14, 4eme étage	SEM-DARBOUX (Séminaire Darboux - physique théorique et mathématiques)	hep-th
Veronica Fantini ( Laboratoire de Mathématiques d'Orsay )	Modular Resurgence
Abstract:	Many physical observables are usually divergent asymptotic expansions, and their divergence is informative. The factorial growth of the coefficients hides non- perturbative, exponentially small corrections, which can be reconstructed by applying Ecalle's theory of resurgence. Sometimes, these observables are also expected to be invariant under the action of a subgroup $\Gamma\subseteq\{\rm SL}_2(\mathbb{Z})$ only up to a holomorphic correction: classical modularity fails, but it does so in a controlled way. Zagier’s notion of a (holomorphic) quantum modular form formalises this controlled failure as a cocycle condition with better analytic properties. In this talk, I will present the framework of modular resurgence, which identifies a class of quantum modular forms by characterizing the resurgent structure of their asymptotics. This has been applied to describe a strong-weak symmetry in topological strings on local Calabi-Yau 3- folds, and to detect the modular structure of certain observables.

Mercredi 7 Avril 2027, 10:30 à IHES, Amphithéâtre Léon Motchane	SEED (Seed Seminar of Mathematics and Physics)	math-ph
Tba	TBA

Mercredi 7 Avril 2027, 11:45 à IHES, Amphithéâtre Léon Motchane	SEED (Seed Seminar of Mathematics and Physics)	math-ph
Tba	TBA

Jeudi 8 Avril 2027, 14:00 à IHP, Choquet Bruhat	RENC-THEO (Rencontres Théoriciennes)	hep-th
Tba	TBA

Jeudi 22 Avril 2027, 10:00 à IHP, Choquet Bruhat	RENC-THEO (Rencontres Théoriciennes)	hep-th
Tba	TBA

Mercredi 5 Mai 2027, 10:00 à IHP, Choquet Bruhat ( Exceptionally a Wednesday )	RENC-THEO (Rencontres Théoriciennes)	hep-th
Tba	TBA

Mercredi 5 Mai 2027, 10:30 à IHES, Amphithéâtre Léon Motchane	SEED (Seed Seminar of Mathematics and Physics)	math-ph
Tba	TBA

Mercredi 5 Mai 2027, 11:45 à IHES, Amphithéâtre Léon Motchane	SEED (Seed Seminar of Mathematics and Physics)	math-ph
Tba	TBA

Jeudi 20 Mai 2027, 10:00 à IHP, Choquet Bruhat	RENC-THEO (Rencontres Théoriciennes)	hep-th
Tba	TBA

Jeudi 3 Juin 2027, 14:00 à IHP, LPTHE library	RENC-THEO (Rencontres Théoriciennes)	hep-th
Tba	TBA