Colloquia & Seminars

Speaker: Sam Bardwell-Evans, Boston University

Title: Scattering Diagrams from Holomorphic Discs in Log Calabi-Yau Surfaces

Algebraic Geometry in String Theory Seminar Speaker: Sam Bardwell-Evans, Boston University Title: Scattering Diagrams from Holomorphic Discs in Log Calabi-Yau Surfaces Abstract: In this talk, we construct special Lagrangian fibrations for log Calabi-Yau surfaces and scattering diagrams from Lagrangian Floer theory of the fibers. These scattering diagrams recover the algebro-geometric scattering diagrams of Gross-Pandharipande-Siebert and Gross-Hacking-Keel. The argument relies on a holomorphic/tropical disc correspondence to control the behavior of holomorphic discs, allowing us to relate open Gromov-Witten invariants to log Gromov-Witten invariants. This talk is based on joint work with Man-Wai Mandy Cheung, Hansol Hong, and Yu-Shen Lin.

Speaker: Zhigang Yao, Harvard CMSA

Title: Principal flow, sub-manifold and boundary

Member Seminar  Speaker: Zhigang Yao Title: Principal flow, sub-manifold and boundary Abstract: While classical statistics has dealt with observations which are real numbers or elements of a real vector space, nowadays many statistical problems of high interest in the sciences deal with the analysis of data which consist of more complex objects, taking values in spaces which are naturally not (Euclidean) vector spaces but which still feature some geometric structure. I will discuss the problem of finding principal components to the multivariate datasets, that lie on an embedded nonlinear Riemannian manifold within the higher-dimensional space. The aim is to extend the geometric interpretation of PCA, while being able to capture the non-geodesic form of variation in the data. I will...

Speaker: Aasmund Folkestad, MIT

Title: The Penrose Inequality as a Constraint on Low Energy Quantum Gravity

Swampland Seminar Speaker: Aasmund Folkestad (MIT) Title: The Penrose Inequality as a Constraint on Low Energy Quantum Gravity Abstract: In this talk, I argue that the Penrose inequality (PI) can be used to constrain low energy theories compatible AdS/CFT, and possibly also quantum gravity in flat space. Focusing on AdS/CFT, it is shown that the PI can be violated for minimally coupled scalar fields, and I produce exclusion plots on couplings that respect the PI. I also present numerical evidence that top-down scalar theories and supersymmetric theories respect the PI. Finally, similar to the Breitenlohner-Freedman bound, I give a necessary condition for the stability AdS that constrains coupling constants (beyond the scalar mass).

Speaker: Jennifer Cano, Stony Brook and Flatiron Institute

Title: Engineering topological phases with a superlattice potential

Topological Quantum Matter Seminar Speaker: Jennifer Cano (Stony Brook and Flatiron Institute) Title: Engineering topological phases with a superlattice potential Abstract: We propose an externally imposed superlattice potential as a platform for manipulating topological phases, which has both advantages and disadvantages compared to a moire superlattice. In the first example, we apply the superlattice potential to the 2D surface of a 3D topological insulator. The superlattice potential creates tunable van Hove singularities, which, when combined with strong spin-orbit coupling and Coulomb repulsion give rise to a topological meron lattice spin texture. Thus, the superlattice potential provides a new route to the long sought-after goal of realizing spontaneous magnetic order on the surface of a 3D TI. In the second example, we...

Speaker: James Cummings, Carnegie Mellon University

Title: Complete disorder is impossible: Some topics in Ramsey theory

Colloquium Title: Complete disorder is impossible: Some topics in Ramsey theory Speaker: James Cummings, Carnegie Mellon University Abstract: The classical infinite Ramsey theorem states that if we colour pairs of natural numbers using two colours, there is an infinite set all of whose pairs get the same colour. This is the beginning of a rich theory, which touches on many areas of mathematics including graph theory, set theory and dynamics. I will give an overview of Ramsey theory, emphasizing the diverse ideas which are at play in this area.

Speaker: Daniel Pomerleano, UMass Boston

Title:

Algebraic Geometry in String Theory Seminar Speaker: Daniel Pomerleano, UMass Boston

Speaker: Leonid Rybnikov, Harvard CMSA

Title: Member Seminar: Title TBA

Speaker: Leonid Rybnikov

Speaker: TBA

Title: Colloquium: Title TBA

Colloquium

Speaker: Yizhuang You, UC San Diego

Title: Symmetric Mass Generation

Topological Quantum Matter Seminar Speaker: Yizhuang You, UC San Diego Title: Symmetric Mass Generation Abstract: Symmetric mass generation (SMG) is a novel mechanism for massless fermions to acquire a mass via a strong-coupling non-perturbative interaction effect. In contrast to the conventional Higgs mechanism for fermion mass generation, the SMG mechanism does not condense any fermion bilinear coupling and preserves the full symmetry. It is connected to a broad range of topics, including anomaly cancellation, topological phase classification, and chiral fermion regularization. In this talk, I will introduce SMG through toy models, and review the current understanding of the SMG transition. I will also mention recent numerical efforts to investigate the SMG phenomenon. I will conclude the talk with...

Speaker: Nicolo Piazzalunga, Rutgers

Title:

Algebraic Geometry in String Theory Seminar Speaker:Nicolo Piazzalunga, Rutgers

Speaker: David Zuckerman, Harvard CMSA

Title: Member Seminar: Title TBA

Speaker: David Zuckerman

Speaker: Bruno Mera, Tohoku University

Title: Kähler bands—Chern insulators, holomorphicity and induced quantum geometry

Topological Quantum Matter Seminar Speaker: Bruno Mera, Tohoku University Title: Kähler bands—Chern insulators, holomorphicity and induced quantum geometry Abstract: The notion of topological phases has dramatically changed our understanding of insulators. There is much to learn about a band insulator beyond the assertion that it has a gap separating the valence bands from the conduction bands. In the particular case of two dimensions, the occupied bands may have a nontrivial topological twist determining what is called a Chern insulator. This topological twist is not just a mathematical observation, it has observable consequences—the transverse Hall conductivity is quantized and proportional to the 1st Chern number of the vector bundle of occupied states over the Brillouin zone. Finer properties of band...

Speaker: Ahsan Khan, IAS

Title:

Algebraic Geometry in String Theory Seminar Speaker: Ahsan Khan, IAS

Speaker: Shuaijie Qian, Harvard CMSA

Title: Member Seminar: Title TBA

Speaker: Shuaijie Qian

Speaker: Mauricio Romo, Harvard CMSA

Title: Member Seminar: Title TBA

Speaker: Mauricio Romo