CMSA

10/3/2019 RM & PT Seminar
2019-10-03 16:30 - 17:00 (America/New_York) | MA

10/3/2019 Spacetime Seminar
2019-10-03 14:30 - 15:00 | MA

10/3/2019 Condensed Matter Seminar
2019-10-03 12:00 - 13:00 | MA

Cohomologies on almost complex manifolds and their applications
2019-10-02 16:30 - 17:30 | CMSA, 20 Garden Street, Cambridge, MA, 02138, United States
Speaker: Spiro Karigiannis (University of Waterloo)

Title: Cohomologies on almost complex manifolds and their applications

Abstract: We define three cohomologies on an almost complex manifold (M, J), defined using the Nijenhuis-Lie derivations induced from the almost complex structure J and its Nijenhuis tensor N, regarded as vector-valued forms on M. One of these can be applied to distinguish non-isomorphic non-integrable almost complex structures on M. Another one, the J-cohomology, is familiar in the integrable case but we extend its definition and applicability to the case of non-integrable almost complex structures. The J-cohomology encodes whether a complex manifold satisfies the “del-delbar-lemma”, and more generally in the non-integrable case the J-cohomology encodes whether (M, J) satisfies a generalization of this lemma. We also mention some other potential cohomologies on almost complex manifolds, related to an interesting question involving the Nijenhuis tensor. This is joint work with Ki Fung Chan and Chi Cheuk Tsang.

10/2/2019 Quantum Matter Seminar
2019-10-02 10:30 - 12:00 | MA

9/30/2019 Math-Physics Seminar
2019-09-30 12:00 - 13:00 | MA

9/26/2019 Spacetime Seminar
2019-09-26 14:30 - 15:00 | MA

9/26/2019 Condensed Matter Seminar
2019-09-26 12:00 - 15:00 | MA

9/26/2019 Quantum Matter Seminar
2019-09-26 12:00 - 13:00 | MA

Double affine Hecke algebras
2019-09-25 16:30 - 17:30 | CMSA, 20 Garden Street, Cambridge, MA, 02138, United States
Speaker: Pavel Etingof (MIT)

Title: Double affine Hecke algebras

Abstract: Double affine Hecke algebras (DAHAs) were introduced by I. Cherednik in the early 1990s to prove Macdonald’s conjectures. A DAHA is the quotient of the group algebra of the elliptic braid group attached to a root system by Hecke relations. DAHAs and their degenerations are now central objects of representation theory. They also have numerous connections to many other fields — integrable systems, quantum groups, knot theory, algebraic geometry, combinatorics, and others. In my talk, I will discuss the basic properties of double affine Hecke algebras and touch upon some applications.

9/25/2019 Fluid Dynamics Seminar
2019-09-25 15:00 - 16:00 | MA

9/25/2019 RM&PT Seminar
2019-09-25 14:08 | MA

9/25/2019 Math-Physics Seminar
2019-09-25 12:00 - 13:00 | MA

9/25/2019 Quantum Matter Seminar
2019-09-25 10:30 - 12:00 | MA

9/20/2019 General Relativity Seminar
2019-09-20 10:30 - 11:30 | MA

9/19/2019 Spacetime Seminar
2019-09-19 14:30 - 16:00 | MA

A taste of noncommutative convex algebraic geometry
2019-09-18 16:30 - 17:30 | CMSA, 20 Garden Street, Cambridge, MA, 02138, United States
Speaker: Bill Helton (UC San Diego)

Title: A taste of noncommutative convex algebraic geometry

Abstract: The last decade has seen the development of a substantial noncommutative (in a free algebra) real and complex algebraic geometry. The aim of the subject is to develop a systematic theory of equations and inequalities for (noncommutative) polynomials or rational functions of matrix variables. Such issues occur in linear systems engineering problems, in free probability (random matrices), and in quantum information theory. In many ways the noncommutative (NC) theory is much cleaner than classical (real) algebraic geometry. For example,

◦ A NC polynomial, whose value is positive semidefinite whenever you plug matrices into it, is a sum of squares of NC polynomials.
◦ A convex NC semialgebraic set has a linear matrix inequality representation.
◦ The natural Nullstellensatz are falling into place.

The goal of the talk is to give a taste of a few basic results and some idea of how these noncommutative problems occur in engineering. The subject is just beginning and so is accessible without much background. Much of the work is joint with Igor Klep who is also visiting CMSA for the Fall of 2019.

9/18/2019 Fluid Dynamics Seminar
2019-09-18 15:00 - 16:00 | MA

9/18/2019 Quantum Matter Seminar
2019-09-18 10:30 - 12:00 | MA

9/16/2019 Math-Physics Seminar
2019-09-16 12:00 - 13:00 | MA

9/13/2019 General Relativity
2019-09-13 10:30 - 23:30 | MA

Spacetime and Quantum Mechanics Seminar
2019-09-12 17:38 | MA
As part of the program on Spacetime and Quantum Mechanics, the CMSA will be hosting a weekly seminar on Thursdays at 2:30pm in room G10.

Date
Speaker
Title/Abstract

9/12/2019
Pasha Pylyavskyy (University of Minnesota)
Title: Vector-relation configurations and plabic graphs

19/18/2019
2:00pm
G02
Francis Brown (University of Oxford)
Title: Amplitudes, Polylogs and Moduli Spaces

9/19/2019
Chuck Doran (University of Alberta)
Title: Calabi-Yau geometry of the N-loop sunset Feynman integrals
Abstract: I will present an overview of the algebraic and transcendental features of the computation of N-loop sunset Feynman integrals.
Starting from the realization of arbitrary Feynman graph hypersurfaces as (generalized) determinantal varieties, we describe the Calabi-Yau subvarieties of permutohedral varieties that arise from the N-loop sunset Feynman graphs and some key features of their geometry and moduli.
These include: (1) an iterated fibration structure which allows one to “bootstrap” both periods and Picard-Fuchs equations from lower N cases; (2) specialization to and interpretation of coincident mass loci (“jump loci”) in moduli; (3) a significant generalization of the Griffiths-Dwork algorithm via “creative telescoping”; and (4) the realization of Calabi-Yau pencils as Landau-Ginzburg models mirror to weak Fano varieties.
Details of each of these will be discussed in later lectures this semester. This is joint work with Pierre Vanhove and Andrey Novoseltsev.

9/26/2019
Tomasz Taylor (Northeastern)
Title: Celestial Amplitudes

10/3/2019
Simon Caron-Huot (McGill)
Title: Poincare Duals of Feynman Integrals

10/10/2019
3:30pm
Yutin Huang (National Taiwan University)
Title: Dualities of Planar Ising Networks and the Positive Orthogonal Grassmannian

10/15/2019
Tuesday
3:30pm

Sergey Fomin (Univ. of Michigan)

Title: “Morsifications and mutations” (joint work with P. Pylyavskyy, E. Shustin, and D. Thurston).

10/18/2019
Friday
G02
Sebastian Franco (The City College of New York)
Title: Graded quivers, generalized dimer models, and topic geometry

10/31/2019
Junjie Rao (Albert Einstein Institute)
Title: All-loop Mondrian Reduction of 4-particle Amplituhedron at Positive Infinity

11/1/2019
SC 232
1:30pm
George Lusztig (MIT)
Title: Total positivity in Springer fibres

11/12/2019
Tuesday
G02
3:30pm

Pierpaolo Mastrolia (University of Padova)
Title: Feynman Integrals and Intersection Theory

11/14/2019
G02
Pierpaolo Mastrolia (University of Padova)
Title: Feynman Integrals and Intersection Theory Pt. II

11/21/2019
Cristian Vergu (Niels Bohr Institute)
Title: The Octagonal Alphabet

11/26/2019
Stephan Stieberger (IAS)
Title: Strings on the Celestial Sphere

12/4/2019
Hadleigh Frost (Oxford)
Title: BCJ numerators, $mathcal{M}_{0,n}$, and ABHY
Abstract: We relate the BCJ numerator Jacobi property to the classical fact that the top homology group of $mathcal{M}_{0,n}$ is isomorphic to a component of the free Lie algebra. We describe ways to get BCJ numerators, and caution that the BCJ Jacobi property doesn’t imply the existence of what has been called a ‘kinematic algebra.’

12/5/2019
David Kosower (IAS)
Title: From scattering amplitudes to classical observables

12/10/2019
Ramis Movassagh (MIT)
Title: Highly entangled quantum spin chains: Exactly solvable counter-examples to the area law
Abstract: In recent years, there has been a surge of activities in proposing “exactly solvable” quantum spin chains with surprising high amount of ground state entanglement–exponentially more than the critical systems that have $log(n)$ von Neumann entropy. We discuss these models from first principles. For a spin chain of length $n$, we prove that the ground state entanglement entropy scales as $sqrt(n)$ and in some cases even extensive (i.e., as $n$) despite the underlying Hamiltonian being: (1) Local (2) Having a unique ground state and (3) Translationally invariant in the bulk. These models have rich connections with combinatorics, random walks, Markov chains, and universality of Brownian excursions. Lastly, we develop techniques for proving the gap. As a consequence, the gap of Motzkin and Fredkin spin chains are proved to vanish as 1/n^c with c>2; this rules out the possibility of these models to be relativistic conformal field theories in the continuum limit. Time permitting we will discuss more recent developments in this direction and ‘generic’ aspects of local spin chains.

9/12/2019 Spacetime Seminar
2019-09-12 14:30 - 16:00 | MA

9/11/2019 Random Matrix
2019-09-11 13:45 - 14:45 | MA

Topology and Dynamics in Quantum Matter Workshop
2019-09-10 09:15 - 2019-09-11 15:25 | CMSA, 20 Garden Street, Cambridge, MA, 02138, United States
On September 10-11, 2019, the CMSA hosted a second workshop on Topological Aspects of Condensed Matter.
New ideas rooted in topology have recently had a major impact on condensed matter physics, and have led to new connections with high energy physics, mathematics and quantum information theory. The aim of this program will be to deepen these connections and spark new progress by fostering discussion and new collaborations within and across disciplines.
Topics include i) the classification of topological states ii) topological orders in two and three dimensions including quantum spin liquids, quantum Hall states and fracton phases and iii) interplay of symmetry and topology in quantum many body systems, including symmetry protected topological phases, symmetry fractionalization and anomalies iv) topological phenomena in quantum systems driven far from equlibrium v) quantum field theory approaches to topological matter.
This workshop is part of the CMSA’s program on Program on Topological Aspects of Condensed Matter, and is the second of two workshops, in addition to a visitor program and seminars.
The workshop was held in room G10 of the CMSA, located at 20 Garden Street, Cambridge, MA.
Organizers: Michael Hermele (CU Boulder) and Ashvin Vishwanath (Harvard)
Partial list of speakers:

Nima Arkani-Hamed, IAS
Jennifer Cano, Stony Brook
Meng Cheng, Yale
Lukasz Fidkowski, UW Seattle
Daniel Freed, Texas
Jeongwan Haah, Microsoft Research
Anton Kapustin, Caltech
Zohar Komargodski, SCGP/Stony Brook
John McGreevy, UC San Diego
Prineha Narang, Harvard
Ying Ran, Boston College
Shinsei Ryu, Chicago
Cumrun Vafa, Harvard
Chong Wang, Perimeter
Zhenghan Wang, Microsoft Station Q

9/9/2019 Math-Physics Seminar
2019-09-09 12:00 - 13:00 | MA

Spacetime and quantum mechanics, total positivity and motives
2019-09-01 09:00 - 2019-12-20 17:00 | CMSA, 20 Garden Street, Cambridge, MA, 02138, United States
Recent developments have poised this area to make serious advances in 2019, and we feel that bringing together many of the relevant experts for an intensive semester of discussions and collaboration will trigger some great things to happen. To this end, the organizers will host a small workshop during Fall 2019, with between 20-30 participants. They will also invite 10-20 longer-term visitors throughout the semester. Additionally, there will be a seminar held weekly on Thursdays at 2:30pm in CMSA G10.
Organizers:

Nima Arkani-Hamed (IAS)
Lauren Williams (Harvard)
Alexander Postnikov (MIT)
Thomas Lam (Michigan)

.
Workshops:

Spacetime and Quantum Mechanics Workshop, October 28-30, 2019

Here is a partial list of the mathematicians and physicists who have indicated that they will attend part or all of this special program as a visitor:

Paolo Benincasa, 11/17/2019 – 11/29/2019
Jacob Bourjaily, 9/1/2019 – 12/15/2019
Francis Brown, 9/15/2019 – 9/20/2019
Simon Caron-Huot, 9/30/2019 – 10/04/2019
Lance Dixon, 9/9/2019 – 9/20/2019
Charles Doran, 10/19/2019 – 11/1/2019
James Drummond, 10/14/2019 – 10/18/2019
Nick Early, 11/18/2019 – 11/22/2019
Livia Ferro, 10/27/2019 – 11/9/2019
Sergey Fomin, 10/6/2019 – 10/16/2019
Sebastian Franco, 10/9/2019 – 10/19/2019
Hadleigh Frost, 9/15/2019 – 12/20/2019
Michael Green, 10/05/2019 – 10/13/2019
Alexander Goncharov, 12/05/2019 – 12/20/2019
Song He, 9/29/2019 – 11/10/2019
Xuhua He, 10/30/2019-11/03/2019
Enrico Herrmann, 10/27/2019 – 11/9/2019
Yutin Huang, 9/30/2019 – 10/12/2019
Steven Karp, 10/11/2019 – 11/03/2019
Tomasz Lukowski, 10/27/2019 – 11/11/2019
Andrew McLeod, 10/6/2019 – 10/19/2019 & 11/3/2019 – 11/16/2019
Sebastian Mizera, 10/28/2019 – 11/1/2019
Erik Panzer, 9/15/2019 – 9/25/2019
Matteo Parisi, 10/26/2019 – 11/10/2019
Julio Parra-Martinez, 10/10/2019 – 05/12/2019
Pierpaolo Mastrolia, 11/8/2019 – 11/16/2019
Pasha Pylyavskyy, 9/8/2019 – 9/22/2019 & 10/14/2019 – 11/1/2019
Junjie Rao, 10/25/2019 – 11/04/2019
Giulio Salvatori, 9/3/2019 – 12/15/2019
Michael Shapiro, 10/27/2019 – 11/2/2019
David Speyer, 10/14/2019 – 10/18/2019
Hugh Thomas, 10/27/2019 – 11/22/2019
Jaroslav Trnka, 9/30/2019 – 10/04/2019, 10/28/2019 – 11/01/2019, 11/18/2019 – 11/22/2019
Cristian Vergu, 11/10/2019 – 11/30/2019
Matthias Volk, 10/14/2019 – 10/25/2019
Matthew von Hippel, 11/11/2019 – 11/22/2019
Pierre Vanhove, 10/22/2019 – 10/31/2019
Matthias Wilhelm, 10/14/2019 – 10/25/2019

Workshop on Foundations of Computational Science
2019-08-29 08:30 - 2019-08-31 14:45 | CMSA, 20 Garden Street, Cambridge, MA, 02138, United States
On August 29-31, 2019 the Center of Mathematical Sciences and Applications hosted a workshop on Foundations of Computational Science. The workshop was held in room G10 of the CMSA, located at 20 Garden Street, Cambridge, MA. This workshop was organized by David Xianfeng Gu.
Speakers:

Sarah Adel Bargal, Boston University
Jianfeng Chen, Harvard
Tat Seng Chua, National University of Singapore
Ke Deng, Tsinghua
David Xianfeng Gu, Stony Brook
Yike Guo, Imperial College London
Minlie Huang, Tsinghua
Scott Kominers, Harvard
Brian Kulis, Boston University
Wee Sun Lee, National University of Singapore
Qianxiao Li, National University of Singapore
Hanzhong Liu, Tsinghua
Jun Liu, Harvard
Xiao-Li Meng, Harvard
Cengiz Pehlevan, Harvard
Donald Rubin, Harvard
Suproteem Sarkar, Harvard
Zuowei Shen, National University of Singapore
Yuanchun Shi, Tsinghua
Justin Solomon, MIT
Hang Su, Tsinghua
Maosong Sun, Tsinghua
Mirac Suzgun, Harvard
Sergiy Verstyuk, CMSA
Xiaoqin Wang, Tsinghua
Bin Xu, Tsinghua
Jun Zhu, Tsinghua
Wenwu Zhu, Tsinghua

2019 Big Data Conference
2019-08-19 08:30 - 2019-08-20 16:40 | CMSA, 20 Garden Street, Cambridge, MA, 02138, United States
On August 19-20, 2019 the CMSA hosted the fifth annual Conference on Big Data. The Conference will featured many speakers from the Harvard community as well as scholars from across the globe, with talks focusing on computer science, statistics, math and physics, and economics.
The talks will take place in Science Center Hall D, 1 Oxford Street.
Videos can be found in the Youtube playlist.

5/28/2019 Topological Aspects of Condensed Matter Special Seminar
2019-05-28 10:30 - 11:42 | MA
