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The Stokes groupoids

Marco Gualtieri University of Toronto

October 23, 2013

PIRSA:13100110
On refined stable pair invariants for del Pezzo surfaces and the 1/2 K3

Albrecht Klemm Rheinische Friedrich-Wilhelms-Universität Bonn

October 23, 2013

PIRSA:13100120
13/14 PSI - Statistical Mechanics - Lecture 12

Anton Burkov University of Waterloo

October 23, 2013

PIRSA:13100060
Topics in QFT on Flat and Curved Spacetimes - Lecture 10

Ugo Moschella University of Insubria

October 23, 2013

PIRSA:13100018
Wall-crossing structures

Yan Soibelman Kansas State University

October 23, 2013

PIRSA:13100119
Blobbed topological recursion

Gaetan Borot

October 22, 2013

PIRSA:13100118
General Relativity for Cosmology - Lecture 11

Achim Kempf University of Waterloo

October 22, 2013

PIRSA:13100004
13/14 PSI - Quantum Field Theory I - Lecture 10

Freddy Cachazo Perimeter Institute for Theoretical Physics

October 22, 2013

PIRSA:13100035
Wilsonian and large N approaches to non-Fermi liquids

Shamit Kachru Stanford University
October 22, 2013

PIRSA:13100109
Condensed Matter
Algebraic structures in massive (2,2) theories

Davide Gaiotto Perimeter Institute for Theoretical Physics

October 22, 2013

PIRSA:13100117
Exact Results In Two-Dimensional (2,2) Supersymmetric Gauge Theories With Boundary

Kentaro Hori University of Tokyo

October 22, 2013

PIRSA:13100116
Conformal symmetry and cosmology

Austin Joyce University of Chicago
October 22, 2013

PIRSA:13100070
Cosmology

The Stokes groupoids

Marco Gualtieri University of Toronto

October 23, 2013

PIRSA:13100110

Ordinary differential equations become much less ordinary when they are allowed to have singularities. Solving them naively in formal power series, one often obtains divergent series, just as in the perturbation series for physical observables in quantum field theory. The asymptotic interpretation of this divergent series exhibits the famous Stokes phenomenon, an essential ingredient in any full description of the solutions to the system. I will explain a new viewpoint on singular ODE which illuminates the geometric meaning of the phenomena described above, and which can be applied to the problem of resummation of formal power series. This viewpoint uses a very basic but underused tool in differential geometry: Lie groupoids. A Lie groupoid is as natural and essential an object as a Lie group; I shall explain how to build examples of them and how to use them to solve singular differential equations.
On refined stable pair invariants for del Pezzo surfaces and the 1/2 K3

Albrecht Klemm Rheinische Friedrich-Wilhelms-Universität Bonn

October 23, 2013

PIRSA:13100120
13/14 PSI - Statistical Mechanics - Lecture 12

Anton Burkov University of Waterloo

October 23, 2013

PIRSA:13100060
Topics in QFT on Flat and Curved Spacetimes - Lecture 10

Ugo Moschella University of Insubria

October 23, 2013

PIRSA:13100018
Wall-crossing structures

Yan Soibelman Kansas State University

October 23, 2013

PIRSA:13100119

The concept of wall-crossing structure (WCS for short) was introduced recently in my joint work with Maxim Kontsevich. WCS appear in different disguises in the theory of Donaldson-Thomas invariants of Calabi-Yau 3-folds, quiver representations,integrable systems of Hitchin type, cluster algebras, Mirror Symmetry, etc.
I plan to discuss the definition of WCS and illustrate it in several well-known examples. If time permits I will speak about a special class of WCS called rational WCS. It gives rise to wall-crossing formulas with factors which are algebraic functions. Conjecturally such WCS appear in Hitchin integrable systems with singularities.
Blobbed topological recursion

Gaetan Borot

October 22, 2013

PIRSA:13100118

Hermitian matrix models have been used since the early days of 2d quantum gravity, as generating series of discrete surfaces, and sometimes toy models for string theory. The single trace matrix models (with measure dM exp( - N Tr V(M)) have been solved in a 1/N expansion in the 90s by the moment method of Ambjorn et al. Later, Eynard showed that it can be rewritten more intrinsically in terms of algebraic geometry of the spectral curve, and formulated the so-called topological recursion. In a similar way, we will show that double hermitian matrix models are solved by the same topological recursion, and more generally, that arbitrary hermitian matrix models are solved by a "blobbed topological recursion", whose properties still have to be investigated.
General Relativity for Cosmology - Lecture 11

Achim Kempf University of Waterloo

October 22, 2013

PIRSA:13100004
13/14 PSI - Quantum Field Theory I - Lecture 10

Freddy Cachazo Perimeter Institute for Theoretical Physics

October 22, 2013

PIRSA:13100035
Wilsonian and large N approaches to non-Fermi liquids

Shamit Kachru Stanford University
October 22, 2013

PIRSA:13100109
Condensed Matter
We use Wilsonian RG and large N techniques to study the quantum field theory of a critical boson interacting with a Fermi surface, and compare/contrast the results with those coming from holography.
Algebraic structures in massive (2,2) theories

Davide Gaiotto Perimeter Institute for Theoretical Physics

October 22, 2013

PIRSA:13100117

I will review some ongoing work on the low energy properties of D-branes/boundary conditions in massive two-dimensional field theories with (2,2) supersymmetry.
Exact Results In Two-Dimensional (2,2) Supersymmetric Gauge Theories With Boundary

Kentaro Hori University of Tokyo

October 22, 2013

PIRSA:13100116

We compute the partition function on the hemisphere of a class of two-dimensional (2,2) supersymmetric field theories including gauged linear sigma models. The result provides a general exact formula for the central charge of the D-brane placed at the boundary. It takes the form of Mellin-Barnes integral and the question of its convergence leads to the grade restriction rule concerning branes near the phase boundaries. We find expressions in various phases including the large volume formula in which a characteristic class called the Gamma class shows up. The two sphere partition function factorizes into two hemispheres glued by inverse to the annulus. The result can also be written in a form familiar in mirror symmetry, and suggests a way to find explicit mirror correspondence between branes.
Conformal symmetry and cosmology

Austin Joyce University of Chicago
October 22, 2013

PIRSA:13100070
Cosmology
We will explore the role that conformal symmetries may play in cosmology. First, we will discuss the symmetries underlying the statistics of the primordial perturbations which seeded the temperature anisotropies of the Cosmic Microwave Background. I will show how symmetry considerations lead us to three broad classes of theories to explain these perturbations: single-field inflation, multi-field inflation, and the conformal mechanism. We will discuss the symmetries in each case and derive their model-independent consequences. Finally, we will examine the possibility of violating the null energy condition with a well-behaved quantum field theory.

Title	Date	Collection	Type	Info
The Stokes groupoids	2013‑10‑23	Colloquium	Scientific Series	View details
On refined stable pair invariants for del Pezzo surfaces and the 1/2 K3	2013‑10‑23	Physics Around Mirror Symmetry	Conference	View details
13/14 PSI - Statistical Mechanics - Lecture 12	2013‑10‑23	13/14 PSI - Statistical Mechanics	Course	View details
Topics in QFT on Flat and Curved Spacetimes - Lecture 10	2013‑10‑23	Topics in QFT on Flat and Curved Spacetimes	Course	View details
Wall-crossing structures	2013‑10‑23	Physics Around Mirror Symmetry	Conference	View details
Blobbed topological recursion	2013‑10‑22	Physics Around Mirror Symmetry	Conference	View details
General Relativity for Cosmology - Lecture 11	2013‑10‑22	General Relativity for Cosmology - 2013	Course	View details
13/14 PSI - Quantum Field Theory I - Lecture 10	2013‑10‑22	13/14 PSI - Quantum Field Theory I	Course	View details
Wilsonian and large N approaches to non-Fermi liquids	2013‑10‑22	Quantum Matter	Scientific Series	View details
Algebraic structures in massive (2,2) theories	2013‑10‑22	Physics Around Mirror Symmetry	Conference	View details
Exact Results In Two-Dimensional (2,2) Supersymmetric Gauge Theories With Boundary	2013‑10‑22	Physics Around Mirror Symmetry	Conference	View details
Conformal symmetry and cosmology	2013‑10‑22	Cosmology and Gravitation	Scientific Series	View details

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