1:00pm Student Topology Seminar: Jiahao Hu - TBA

**Where:** Math Tower 5-127**When:** Mon, Feb 24 1:00pm — 2:00pm

**Title:** TBA

**Speaker:** Jiahao Hu [Stony Brook University]

**Abstract:** TBA

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1:30pm Mirror Symmetry Reading Seminar: Hang Yuan - SYZ for Divisor Complement and Wall Crossing 2

**Where:** Math Tower 4-130**When:** Mon, Feb 24 1:30pm — 2:30pm

**Title:** SYZ for Divisor Complement and Wall Crossing 2

**Speaker:** Hang Yuan [Stony Brook University]

**Abstract:** We will continue the previous talk on the Auroux's paper "Mirror symmetry and T-duality in the complement of an anti-canonical divisor". We will discuss various structures on moduli spaces of special Lagrangians with flat U(1)-bundles. We will also check step by step lots of related computations.

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2:30pm **SCGP:** Dynamics and Renormalization Seminar: Maria Gordina, University of Connecticut

**Where:** 313**When:** Mon, Feb 24 2:30pm — 3:30pm

**Title:** Ergodicity for Langevin dynamics with singular potentials

**Abstract:** We discuss Langevin dynamics of N particles on R^d interacting through a singular repulsive potential, such as the Lennard-Jones potential, and show that the system converges to the unique invariant Gibbs measure exponentially fast in a weighted total variation distance. The proof relies on an explicit construction of a Lyapunov function using a modified Gamma calculus (curvature-dimension condition). In contrast to previous results for such systems, we prove geometric convergence to equilibrium starting from an essentially optimal family of initial distributions. This is based on joint work with F.Baudoin and D.Herzog.

2:30pm Dynamics and Renormalization Seminar: Maria Gordina - Ergodicity for Langevin dynamics with singular potentials

**Where:** SCGP 313**When:** Mon, Feb 24 2:30pm — 3:30pm

**Title:** Ergodicity for Langevin dynamics with singular potentials

**Speaker:** Maria Gordina [University of Connecticut]

**Abstract:** We discuss Langevin dynamics of N particles on R^d interacting through a singular repulsive potential, such as the Lennard-Jones potential, and show that the system converges to the unique invariant Gibbs measure exponentially fast in a weighted total variation distance. The proof relies on an explicit construction of a Lyapunov function using a modified Gamma calculus (curvature-dimension condition). In contrast to previous results for such systems, we prove geometric convergence to equilibrium starting from an essentially optimal family of initial distributions. This is based on joint work with F.Baudoin and D.Herzog.

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11:30am **SCGP:** Dynamics and Renormalization Seminar: Alexander Teplyaev, University of Connecticut

**Where:** P116**When:** Tue, Feb 25 11:30am — 12:30pm

**Title:** Spectral analysis on self-similar graphs and fractals

**Abstract:** The talk will describe how spectral theory, geometry of graphs, and dynamical systems are used to analyze spectral properties of the random walk generator on finitely ramified self-similar graphs and fractals. In particular, pure point or singular continuous spectrum appears naturally for such graphs. The standard examples include the Sierpinski triangle, the Vicsek tree, and the Schreier graphs of the Hanoi self-similar group studied by Grigorchuk and Sunic. A more complicated example is related to the Basilica Julia set of the polynomial z^2-1 and its Iterated Monodromy Group, defined by Nekrashevych. Its spectrum was investigated numerically by Strichartz et al and analytically in a joint work with Luke Rogers and several students at UConn.

11:30am Dynamics and Renormalization Seminar: Alexander Teplyaev - Spectral analysis on self-similar graphs and fractals.

**Where:** Physics P116**When:** Tue, Feb 25 11:30am — 12:30pm

**Title:** Spectral analysis on self-similar graphs and fractals.

**Speaker:** Alexander Teplyaev [University of Connecticut]

**Abstract:** The talk will describe how spectral theory, geometry of graphs, and dynamical systems are used to analyze spectral properties of the random walk generator on finitely ramified self-similar graphs and fractals. In particular, pure point or singular continuous spectrum appears naturally for such graphs. The standard examples include the Sierpinski triangle, the Vicsek tree, and the Schreier graphs of the Hanoi self-similar group studied by Grigorchuk and Sunic. A more complicated example is related to the Basilica Julia set of the polynomial z^2-1 and its Iterated Monodromy Group, defined by Nekrashevych. Its spectrum was investigated numerically by Strichartz et al and analytically in a joint work with Luke Rogers and several students at UConn.

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1:00pm **SCGP:** SCGP Weekly Talk: Alexander Teplyaev

**Where:** 102**When:** Tue, Feb 25 1:00pm — 2:00pm

**Title:** Diffusions on singular spaces.

**Abstract:** On many classical fractal spaces, such as the Sierpinski triangle and square, there are natural and essentially unique diffusion processes which do not obey the classical Einstein relation: the distance traveled by the diffusion is not proportional to the square root of time. However, there are uniquely defined spectral and walk dimensions which determine the behavior of these diffusion processes via so called generalized Einstein relation. Surprisingly, these dimensions appeared recently in the physics theories of the quantum gravity involving theoretical and numerical analysis of the casual dynamical triangulations. If time permits, I'll also briefly describe singular diffusions on the pattern spaces of aperiodic Delone sets, e.g. a quasicrystal lattice or a Penrose tiling (a joint work with Patricia Alonso-Ruiz, Michael Hinz and Rodrigo Trevino). The presentation will be non-technical, and no prior knowledge about fractals or diffusion processes will be assumed.

2:30pm **YITP:** Victor Gorbenko (IAS) - "On Quantum Field Theory in de Sitter"

**When:** Tue, Feb 25 2:30pm — 3:30pm

4:00pm **SCGP:** Physics Colloquium

**Where:** Location: Harriman 137**When:** Tue, Feb 25 4:00pm — 5:00pm

Coffee & Tea served at 3:45 pm.

Talk begins at 4:15 pm.

Full schedule of speakers can be found here: http://www.physics.sunysb.edu/Physics/colloquium/2019/

Movies: To watch the recorded movies, please read the instructions here.

2:00pm **SCGP:** Physics Seminar: Beatrix Muhlmann

**Where:** 313**When:** Wed, Feb 26 2:00pm — 3:00pm

**Title:** Gravitational anomalies in nAdS_2/nCFT_1

**Abstract:** I will discuss some recent work in the framework of nAdS_2/nCFT_1, based on 1911.11434. We revisit the holographic description of the near-horizon geometry of the BTZ black hole in AdS_3 gravity with a gravitational Chern Simons term included. A dimensional reduction of this theory allows us to investigate the relation between UV and IR data, and in particular where inside the CFT_2 the nCFT_1 sits.

4:00pm Algebraic geometry seminar: Michael Kemeny - A very simple proof of Voisin's Theorem on Canonical Curves

**Where:** Math Tower P-131**When:** Wed, Feb 26 4:00pm — 5:30pm

**Title:** A very simple proof of Voisin's Theorem on Canonical Curves

**Speaker:** Michael Kemeny [University of Wisconsin -- Madison]

**Abstract:** The classical theorems of Noether and Petri on the ideals of canonically embedded curves are central in the theory of curves. In the 80s, Mark Green realized that these results should extend to a far broader statement about the entire resolution of the ideal. No major progress was made until Voisin resolved this conjecture for generic curves in 02 and 05. Voisin's proof was extremely sophisticated and used in a deep way the geometry of the situation. We will give a very simple and short proof of her result, using nothing more than the basic yoga developed by Green, Ein and Lazarsfeld in the 80s. In the case of even genus, we will show how the proof our resolves a deeper (and previously open) conjecture, due to Schreyer, describing in depth the structure of the extremal syzygy space.

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1:00pm Symplectic Geometry Seminar: Laura Starkston - Weinstein Trisections

**Where:** Math Tower 5-127**When:** Thu, Feb 27 1:00pm — 2:30pm

**Title:** Weinstein Trisections

**Speaker:** Laura Starkston [UC Davis]

**Abstract:** Gay and Kirby proved that every smooth 4-manifold admits a trisection--a decomposition into three pieces, each of which is a 1-handlebody. A Weinstein trisection is a trisection which is nicely compatible with a symplectic structure on the 4-manifold. We will explain this structure and show that every symplectic 4-manifold admits a Weinstein trisection. This is joint work with Peter Lambert-Cole and Jeffrey Meier.

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2:00pm **SCGP:** Physics Seminar: Eliezer Rabinovici

**Where:** 313, **When:** Thu, Feb 27 2:00pm — 3:00pm

**Title:** Operator complexity growth at short and long time scales

**Abstract:** In the framework of the AdS/CFT correspondence, the problem of explaining the structure of some correlation functions for large temporal and spatial separations, is tied to non perturbative properties. For spatial separations behind a Black Hole horizon this led to the introduction of a notion of quantum complexity as a significant feature of the boundary QFT . The quantum complexity continues to evolve for times much far longer than thermalization time scales. Several definitions were proposed for the definition of complexity in the boundary QFT, and its precise holographic dual. After reviewing some definitions of Complexity in the QFT and their proposed duals we introduce and explore a definition of operator complexity which depends only on the starting operator and the Hamiltonian of the system and does not depend on tolerance parameters. We analyze its behavior at short and long times for a finite system and find that they reproduce generic features one expects for complexity of quantum many-body systems.

4:00pm Colloquium: Richard Melrose - An analytic Dirac-Ramond operator

**Where:** Math Tower P-131**When:** Thu, Feb 27 4:00pm — 5:00pm

**Title:** An analytic Dirac-Ramond operator

**Speaker:** Richard Melrose [MIT]

**Abstract:** Starting in the 1970s the concept of a Dirac operator on the

loop space of a manifold was developed by Physicists, culminating in the

construction of

a formal index theorem leading to an object in elliptic cohomology. I

will describe progress on developing the mathematical structures

which allow this operator to be realized analytically and some of the

obstacles remaining to the formulation of its index.

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loop space of a manifold was developed by Physicists, culminating in the

construction of

a formal index theorem leading to an object in elliptic cohomology. I

will describe progress on developing the mathematical structures

which allow this operator to be realized analytically and some of the

obstacles remaining to the formulation of its index.

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