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X-WR-CALDESC:Events for CMSA
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TZID:America/New_York
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BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211209T093000
DTEND;TZID=America/New_York:20211209T143000
DTSTAMP:20250328T200233Z
CREATED:20230705T082223Z
LAST-MODIFIED:20250328T200233Z
UID:10000072-1639042200-1639060200@live-hu-cmsa-222.pantheonsite.io
SUMMARY:CMSA Math-Science Literature Lecture - Karen Uhlenbeck
DESCRIPTION:Karen Uhlenbeck (Institute for Advanced Study) \nTitle: The Noether Theorems in Geometry: Then and Now \nAbstract: The 1918 Noether theorems were a product of the general search for energy and momentum conservation in Einstein’s newly formulated theory of general relativity. Although widely referred to as the connection between symmetry and conservation laws\, the theorems themselves are often not understood properly and hence have not been as widely used as they might be. In the first part of the talk\, I outline a brief history of the theorems\, explain a bit of the language\, translate the first theorem into coordinate invariant language and give a few examples. I will mention only briefly their importance in physics and integrable systems. In the second part of the talk\, I describe why they are still relevant in geometric analysis: how they underlie standard techniques and why George Daskalopoulos and I came to be interested in them for our investigation into the best Lipschitz maps of Bill Thurston. Some applications to integrals on a domain a hyperbolic surface leave open possibilities for applications to integrals on domains which are locally symmetric spaces of higher dimension. The talk finishes with an example or two from the literature. \nTalk Chair: Laura DeMarco \nVIDEO
URL:https://live-hu-cmsa-222.pantheonsite.io/event/12-9-21-math-science-literature-lecture-karen-uhlenbeck/
LOCATION:Virtual
CATEGORIES:Event,Math Science Literature Lecture Series,Public Lecture,Special Lectures
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/Lecture_Uhlenbeck_12921.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211208T140000
DTEND;TZID=America/New_York:20211208T150000
DTSTAMP:20240515T203917Z
CREATED:20230808T175752Z
LAST-MODIFIED:20240515T203917Z
UID:10001201-1638972000-1638975600@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Hierarchical Transformers are More Efficient Language Models
DESCRIPTION:Speaker: Piotr Nawrot\, University of Warsaw \nTitle: Hierarchical Transformers are More Efficient Language Models \nAbstract: Transformer models yield impressive results on many NLP and sequence modeling tasks. Remarkably\, Transformers can handle long sequences which allows them to produce long coherent outputs: full paragraphs produced by GPT-3 or well-structured images produced by DALL-E. These large language models are impressive but also very inefficient and costly\, which limits their applications and accessibility. We postulate that having an explicit hierarchical architecture is the key to Transformers that efficiently handle long sequences. To verify this claim\, we first study different ways to upsample and downsample activations in Transformers so as to make them hierarchical. We use the best performing upsampling and downsampling layers to create Hourglass – a hierarchical Transformer language model. Hourglass improves upon the Transformer baseline given the same amount of computation and can yield the same results as Transformers more efficiently. In particular\, Hourglass sets new state-of-the-art for Transformer models on the ImageNet32 generation task and improves language modeling efficiency on the widely studied enwik8 benchmark.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/12-8-21-new-technologies-in-mathematics/
LOCATION:Virtual
CATEGORIES:New Technologies in Mathematics Seminar
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-NTM-Seminar-12.08.21.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211208T103000
DTEND;TZID=America/New_York:20211208T120000
DTSTAMP:20240301T083428Z
CREATED:20240214T094451Z
LAST-MODIFIED:20240301T083428Z
UID:10002644-1638959400-1638964800@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Defects\, link invariants and exact WKB
DESCRIPTION:Speaker: Fei Yan (Rutgers) \nTitle: Defects\, link invariants and exact WKB \nAbstract: I will describe some of my recent work on defects in supersymmetric field theories. The first part of my talk is focused on line defects in certain large classes of 4d N=2 theories and 3d N=2 theories. I will describe geometric methods to compute the ground states spectrum of the bulk-defect system\, as well as implications on the construction of link invariants. In the second part I will talk about some perspectives of surface defects in 4d N=2 theories and related applications on the exact WKB method for ordinary differential equations. This talk is based on past joint work with A. Neitzke\, various work in progress with D. Gaiotto\, S. Jeong\, A. Khan\, G. Moore\, as well as work by myself.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/12-8-2021-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-QMMP-12.08.21-1544x2048-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211207T093000
DTEND;TZID=America/New_York:20211207T103000
DTSTAMP:20240122T054102Z
CREATED:20230818T050741Z
LAST-MODIFIED:20240122T054102Z
UID:10001286-1638869400-1638873000@live-hu-cmsa-222.pantheonsite.io
SUMMARY:2d N=(0\,1) gauge theories\, Spin(7) orientifolds and triality
DESCRIPTION:
URL:https://live-hu-cmsa-222.pantheonsite.io/event/12-7-21-algebraic-geometry-in-string-theory/
LOCATION:Virtual
CATEGORIES:Algebraic Geometry in String Theory Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211201T140000
DTEND;TZID=America/New_York:20211201T143000
DTSTAMP:20240515T203641Z
CREATED:20230808T175251Z
LAST-MODIFIED:20240515T203641Z
UID:10001200-1638367200-1638369000@live-hu-cmsa-222.pantheonsite.io
SUMMARY:The Principles of Deep Learning Theory
DESCRIPTION:Speaker: Dan Roberts\, MIT & Salesforce \nTitle: The Principles of Deep Learning Theory \nAbstract: Deep learning is an exciting approach to modern artificial intelligence based on artificial neural networks. The goal of this talk is to provide a blueprint — using tools from physics — for theoretically analyzing deep neural networks of practical relevance. This task will encompass both understanding the statistics of initialized deep networks and determining the training dynamics of such an ensemble when learning from data. \nIn terms of their “microscopic” definition\, deep neural networks are a flexible set of functions built out of many basic computational blocks called neurons\, with many neurons in parallel organized into sequential layers. Borrowing from the effective theory framework\, we will develop a perturbative 1/n expansion around the limit of an infinite number of neurons per layer and systematically integrate out the parameters of the network. We will explain how the network simplifies at large width and how the propagation of signals from layer to layer can be understood in terms of a Wilsonian renormalization group flow. This will make manifest that deep networks have a tuning problem\, analogous to criticality\, that needs to be solved in order to make them useful. Ultimately we will find a “macroscopic” description for wide and deep networks in terms of weakly-interacting statistical models\, with the strength of the interactions between the neurons growing with depth-to-width aspect ratio of the network. Time permitting\, we will explain how the interactions induce representation learning. \nThis talk is based on a book\, The Principles of Deep Learning Theory\, co-authored with Sho Yaida and based on research also in collaboration with Boris Hanin. It will be published next year by Cambridge University Press.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/12-1-21-new-technologies-in-mathematics-seminar-series/
LOCATION:Virtual
CATEGORIES:New Technologies in Mathematics Seminar
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-NTM-Seminar-12.01.21.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211130T093000
DTEND;TZID=America/New_York:20211130T103000
DTSTAMP:20240122T053703Z
CREATED:20230818T050118Z
LAST-MODIFIED:20240122T053703Z
UID:10001285-1638264600-1638268200@live-hu-cmsa-222.pantheonsite.io
SUMMARY:K_2 and Quantum Curves
DESCRIPTION:
URL:https://live-hu-cmsa-222.pantheonsite.io/event/k_2-and-quantum-curves/
LOCATION:Virtual
CATEGORIES:Algebraic Geometry in String Theory Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211124T103000
DTEND;TZID=America/New_York:20211124T120000
DTSTAMP:20240301T084626Z
CREATED:20240214T100439Z
LAST-MODIFIED:20240301T084626Z
UID:10002655-1637749800-1637755200@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Multipartitioning topological phases and quantum entanglement
DESCRIPTION:Speaker: Shinsei Ryu (Princeton University) \nTitle: Multipartitioning topological phases and quantum entanglement \nAbstract: We discuss multipartitions of the gapped ground states of (2+1)-dimensional topological liquids into three (or more) spatial regions that are adjacent to each other and meet at points. By considering the reduced density matrix obtained by tracing over a subset of the regions\, we compute various correlation measures\, such as entanglement negativity\, reflected entropy\, and associated spectra. We utilize the bulk-boundary correspondence to achieve such multipartitions and construct the reduced density matrix near the entangling boundaries. We find the fingerprints of topological liquid in these quantities\, such as (universal pieces in) the scaling of the entanglement negativity\, and a non-trivial distribution of the spectrum of the partially transposed density matrix.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/11-24-2021-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-QMMP-11.24.21-1583x2048-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211118T143000
DTEND;TZID=America/New_York:20211118T160000
DTSTAMP:20240301T090528Z
CREATED:20240214T100731Z
LAST-MODIFIED:20240301T090528Z
UID:10002657-1637245800-1637251200@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Exact Eigenstates in Non-Integrable Systems: A violation of the ETH
DESCRIPTION:Speaker: B. Andrei Bernevig (Princeton University) \nTitle: Exact Eigenstates in Non-Integrable Systems: A violation of the ETH \nAbstract: We find that several non-integrable systems exhibit some exact eigenstates that span the energy spectrum from lowest to the highest state. In the AKLT Hamiltonian and in several others “special” non-integrable models\, we are able to obtain the analytic expression of states exactly and to compute their entanglement spectrum and entropy to show that they violate the eigenstate thermalization hypothesis. This represented the first example of ETH violation in a non-integrable system; these types of states have gained notoriety since then as quantum Scars in the context of Rydberg atoms experiments. We furthermore show that the structure of these states\, in most models where they are found is that of an almost spectrum generating algebra which we call Restricted Spectrum Generating Algebra. This includes the (extended) Hubbard model\, as well as some thin-torus limits of Fractional Quantum Hall states. Yet in other examples\, such as the recently found chiral non-linear Luttinger liquid\, their structure is more complicated and not understood.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/11-18-2021-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-Quantum-Matter-in-Mathematics-and-Physics-11.18.21-1583x2048-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211116T150000
DTEND;TZID=America/New_York:20211116T163000
DTSTAMP:20240301T090706Z
CREATED:20240214T101038Z
LAST-MODIFIED:20240301T090706Z
UID:10002660-1637074800-1637080200@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Quantum Geometric Aspects of Chiral Twisted Graphene Models
DESCRIPTION:Speaker: Jie Wang (Simons Foundation) \nTitle: Quantum Geometric Aspects of Chiral Twisted Graphene Models \nAbstract: “Moire” materials produced by stacking monolayers with small relative twist angles are of intense current interest for the range of correlated electron phenomena they exhibit. The quench of the kinetic energy means that the interacting physics is controlled by the interplay between the interaction scale and intrinsic quantum geometries of the flat band states\, in particular the Berry curvature and the Fubini-Study metric\, which are in general spatially non-uniform. We show that the analytical solution of the twisted bilayer graphene wavefunction in the chiral limit has a special band geometry\, endowing the Brillouin zone with a complex structure. This talk focus on the origin of the momentum space complex structure\, concrete models that realize it\, and its implications to electron-electron interactions. We first show the momentum space complex structure in Chern number C=1 flatbands implies the Bloch wavefunction to exhibit an exact correspondence to the lowest Landau level in the dual momentum space [2]. We present a generalization of the Haldane pseudopotential concept to deal with interacting problems in these bands and discuss experimental implications [2]. We also present an analytically solvable multi-layer generalized chiral graphene model\, which exhibits arbitrarily high Chern number and ideal quantum geometries [3]. Numerical studies of interacting particles indicate model fractional Chern insulators without Landau level analogues\, characterized by exact degeneracies and infinite particle entanglement spectra gaps [3]. References: \n[1] Jie Wang\, Yunqin Zheng\, Andrew J. Millis\, Jennifer Cano (Phys. Rev. Research 3\, 023155)\n[2] Jie Wang\, Jennifer Cano\, Andrew J. Millis\, Zhao Liu\, Bo Yang (arXiv: 2105.07491\, to appear in PRL)\n[3] Jie Wang\, Zhao Liu (arXiv: 2109.10325)
URL:https://live-hu-cmsa-222.pantheonsite.io/event/11-16-2021-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211112T143000
DTEND;TZID=America/New_York:20211112T160000
DTSTAMP:20240301T090838Z
CREATED:20240214T101408Z
LAST-MODIFIED:20240301T090838Z
UID:10002663-1636727400-1636732800@live-hu-cmsa-222.pantheonsite.io
SUMMARY:A degeneracy bound for homogeneous topological order
DESCRIPTION:Speaker: Jeongwan Haah (Microsoft) \nTitle: A degeneracy bound for homogeneous topological order
URL:https://live-hu-cmsa-222.pantheonsite.io/event/11-12-2021-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211103T140000
DTEND;TZID=America/New_York:20211103T153000
DTSTAMP:20240301T091205Z
CREATED:20240214T102259Z
LAST-MODIFIED:20240301T091205Z
UID:10002667-1635948000-1635953400@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Non-Invertible Duality Defects in 3+1 Dimensions
DESCRIPTION:Speaker: Clay Cordova (U Chicago) \nTitle: Non-Invertible Duality Defects in 3+1 Dimensions \nAbstract:  For any quantum system invariant under gauging a higher-form global symmetry\, we construct a non-invertible topological defect by gauging in only half of spacetime. This generalizes the Kramers-Wannier duality line in 1+1 dimensions to higher spacetime dimensions. We focus on the case of a one-form symmetry in 3+1 dimensions and determine the fusion rule. From modular invariance and a direct analysis of one-form symmetry-protected topological phases\, we show that the existence of certain kinds of duality defects is intrinsically incompatible with a trivially gapped phase. By further assuming time-reversal symmetry\, we find that the presence of certain duality defects implies that the low-energy phase has to be gapless unless the one-form symmetry is spontaneously broken. We give an explicit realization of this duality defect in the free Maxwell theory where the duality defect is realized by a Chern-Simons coupling between the gauge fields from the two sides.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/11-3-3021-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211029T120000
DTEND;TZID=America/New_York:20211029T130000
DTSTAMP:20240301T091452Z
CREATED:20240214T102641Z
LAST-MODIFIED:20240301T091452Z
UID:10002670-1635508800-1635512400@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Anomaly resolution via decomposition
DESCRIPTION:Speaker: Eric Sharpe (Virginia Tech) \nTitle: Anomaly resolution via decomposition \nAbstract: In this talk we will discuss a method of anomaly resolution due to Wang-Wen-Witten in the special case of (1+1) dimensional theories. Briefly\, for our purposes\, Wang-Wen-Witten argued that an ill-defined anomalous orbifold [X/G] could be resolved by extending G to a larger group and adding suitable phases.  We analyze this process from the perspective of decomposition\, a property of (1+1)-dimensional theories with “one-form symmetries” first described in 2006.  Examples of such theories include orbifolds with trivially-acting subgroups\, of which the extensions of [X/G] are examples.  After a review of decomposition\, we will see that decomposition implies that in (1+1) dimensions\, the Wang-Wen-Witten procedure results in orbifolds that are equivalent to disjoint unions of orbifolds of X by explicitly nonanomalous subgroups of G.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/10-29-2021-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211021T153000
DTEND;TZID=America/New_York:20211021T170000
DTSTAMP:20240301T091902Z
CREATED:20240214T102900Z
LAST-MODIFIED:20240301T091902Z
UID:10002672-1634830200-1634835600@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Electric-magnetic duality and the Geometric Langlands duality
DESCRIPTION:Title: Electric-magnetic duality and the Geometric Langlands duality \nAbstract: I will give a pedagogical review of the connection between electric-magnetic duality and the Geometric Langlands duality.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/10-21-2021-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211020T093000
DTEND;TZID=America/New_York:20211020T103000
DTSTAMP:20240507T193206Z
CREATED:20240214T043359Z
LAST-MODIFIED:20240507T193206Z
UID:10002530-1634722200-1634725800@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Categorification and applications
DESCRIPTION:Speaker: Peng Shan (Tsinghua University)\n\n\n\nTitle: Categorification and applications \nAbstract: I will give a survey of the program of categorification for quantum groups\, some of its recent development and applications to representation theory.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/categorification-and-applications/
LOCATION:Virtual
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-Colloquium-10.20.21.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211014T090000
DTEND;TZID=America/New_York:20211014T100000
DTSTAMP:20240529T180858Z
CREATED:20240214T082843Z
LAST-MODIFIED:20240529T180858Z
UID:10002588-1634202000-1634205600@live-hu-cmsa-222.pantheonsite.io
SUMMARY:D3C: Reducing the Price of Anarchy in Multi-Agent Learning
DESCRIPTION:Speaker: Ian Gemp\, DeepMind \nTitle: D3C: Reducing the Price of Anarchy in Multi-Agent Learning \nAbstract: In multi-agent systems the complex interaction of fixed incentives can lead agents to outcomes that are poor (inefficient) not only for the group but also for each individual agent. Price of anarchy is a technical game theoretic definition introduced to quantify the inefficiency arising in these scenarios– it compares the welfare that can be achieved through perfect coordination against that achieved by self-interested agents at a Nash equilibrium. We derive a differentiable upper bound on a price of anarchy that agents can cheaply estimate during learning. Equipped with this estimator agents can adjust their incentives in a way that improves the efficiency incurred at a Nash equilibrium. Agents adjust their incentives by learning to mix their reward (equiv. negative loss) with that of other agents by following the gradient of our derived upper bound. We refer to this approach as D3C. In the case where agent incentives are differentiable D3C resembles the celebrated Win-Stay Lose-Shift strategy from behavioral game theory thereby establishing a connection between the global goal of maximum welfare and an established agent-centric learning rule. In the non-differentiable setting as is common in multiagent reinforcement learning we show the upper bound can be reduced via evolutionary strategies until a compromise is reached in a distributed fashion. We demonstrate that D3C improves outcomes for each agent and the group as a whole on several social dilemmas including a traffic network exhibiting Braess’s paradox a prisoner’s dilemma and several reinforcement learning domains.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/10-14-2021-interdisciplinary-science-seminar/
LOCATION:Virtual
CATEGORIES:Interdisciplinary Science Seminar
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-Interdisciplinary-Science-Seminar-10.14.21.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211007T115400
DTEND;TZID=America/New_York:20211007T135400
DTSTAMP:20240301T092837Z
CREATED:20240214T090253Z
LAST-MODIFIED:20240301T092837Z
UID:10002604-1633607640-1633614840@live-hu-cmsa-222.pantheonsite.io
SUMMARY:A tour of categorical symmetry
DESCRIPTION:Title: A tour of categorical symmetry \nAbstract: I will discuss some perspectives on symmetry coming from the study of topological defects in quantum field theory. I will argue that we should take topological defects themselves to define the symmetries of QFT. This gives us a view of the “category of QFTs”. I will describe some examples of these “categorical symmetries”\, their applications\, and some open problems.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/10-7-2021-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211006T114900
DTEND;TZID=America/New_York:20211006T134900
DTSTAMP:20240301T093241Z
CREATED:20240214T090718Z
LAST-MODIFIED:20240301T093241Z
UID:10002606-1633520940-1633528140@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Line defects in CFTs: Renormalization group flows and semiclassical limits
DESCRIPTION:Title: Line defects in CFTs: Renormalization group flows and semiclassical limits \nAbstract: I will discuss line defects in d-dimensional Conformal Field Theories (CFTs). In the first part of the talk\, I will argue that the ambient CFT places nontrivial constraints on Renormalization Group (RG) flows on such line defects. I will show that the flow on line defects is consequently irreversible and furthermore a canonical decreasing entropy function exists. This construction generalizes the g theorem to line defects in arbitrary dimensions.  In the second part of the talk\, I will present some applications. In particular\, I will discuss impurities with large isospin S for some O(3) symmetric theories in the epsilon expansion.  For sufficiently large S diagrammatic perturbation theory breaks down\, and these are studied in a semiclassical expansion at fixed epsilon S.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/10-6-2021-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211006T093000
DTEND;TZID=America/New_York:20211006T103000
DTSTAMP:20240501T205719Z
CREATED:20240214T044013Z
LAST-MODIFIED:20240501T205719Z
UID:10002532-1633512600-1633516200@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Strings\, knots and quivers
DESCRIPTION:Speaker: Piotr Sułkowski (University of Warsaw) \nTitle: Strings\, knots and quivers \nAbstract: I will discuss a recently discovered relation between quivers and knots\, as well as – more generally – toric Calabi-Yau manifolds. In the context of knots this relation is referred to as the knots-quivers correspondence\, and it states that various invariants of a given knot are captured by characteristics of a certain quiver\, which can be associated to this knot. Among others\, this correspondence enables to prove integrality of LMOV invariants of a knot by relating them to motivic Donaldson-Thomas invariants of the corresponding quiver\, it provides a new insight on knot categorification\, etc. This correspondence arises from string theory interpretation and engineering of knots in brane systems in the conifold geometry; replacing the conifold by other toric Calabi-Yau manifolds leads to analogous relations between such manifolds and quivers.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/strings-knots-and-quivers/
LOCATION:Virtual
CATEGORIES:Colloquium
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211004T110000
DTEND;TZID=America/New_York:20211004T123000
DTSTAMP:20250409T192600Z
CREATED:20240212T110410Z
LAST-MODIFIED:20250409T192600Z
UID:10002032-1633345200-1633350600@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Math Science Lectures in Honor of Raoul Bott: Michael Freedman
DESCRIPTION:On October 4th and October 5th\, 2021\, Harvard CMSA hosted the annual Math Science Lectures in Honor of Raoul Bott. This year’s speaker was Michael Freedman (Microsoft). The lectures took place on Zoom. \nThis will be the third annual lecture series held in honor of Raoul Bott. \n\n\n\n\nLecture 1\nOctober 4th\, 11:00am (Boston time)\nTitle: The Universe from a single Particle \nAbstract: I will explore a toy model  for our universe in which spontaneous symmetry breaking – acting on the level of operators (not states) – can produce the interacting physics we see about us from the simpler\, single particle\, quantum mechanics we study as undergraduates. Based on joint work with Modj Shokrian Zini\, see arXiv:2011.05917 and arXiv:2108.12709. \nVideo\n\n\nLecture 2\nOctober 5th\, 11:00am (Boston time)\nTitle: Controlled Mather Thurston Theorems. \nAbstract: The “c-principle” is a cousin of Gromov’s h-principle in which cobordism rather than homotopy is required to (canonically) solve a problem. We show that in certain well-known c-principle contexts only the mildest cobordisms\, semi-s-cobordisms\, are required. In physical applications\, the extra topology (a perfect fundamental group) these cobordisms introduce could easily be hidden in the UV. This leads to a proposal to recast gauge theories such as EM and the standard model in terms of flat connections rather than curvature. See arXiv:2006.00374   \nVideo\n\n\n\n 
URL:https://live-hu-cmsa-222.pantheonsite.io/event/math-science-lectures-in-honor-of-raoul-bott-3/
LOCATION:Virtual
CATEGORIES:Event,Math Science Lectures in Honor of Raoul Bott,Special Lectures
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20210929T171500
DTEND;TZID=America/New_York:20210929T181500
DTSTAMP:20240304T065421Z
CREATED:20240214T055645Z
LAST-MODIFIED:20240304T065421Z
UID:10002546-1632935700-1632939300@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Langlands duality for 3 manifolds
DESCRIPTION:Speaker: David Jordan (U Edinburgh) \nTitle: Langlands duality for 3 manifolds \nAbstract: Langlands duality began as a deep and still mysterious conjecture in number theory\, before branching into a similarly deep and mysterious conjecture of Beilinson and Drinfeld concerning the algebraic geometry of Riemann surfaces. In this guise it was given a physical explanation in the framework of 4-dimensional super symmetric quantum field theory by Kapustin and Witten.  However to this day the Hilbert space attached to 3-manifolds\, and hence the precise form of Langlands duality for them\, remains a mystery. \nIn this talk I will propose that so-called “skein modules” of 3-manifolds give natural candidates for these Hilbert spaces at generic twisting parameter Psi \, and I will explain a Langlands duality in this setting\, which we have conjectured with Ben-Zvi\, Gunningham and Safronov. \nIntriguingly\, the precise formulation of such a conjecture in the classical limit Psi=0 is still an open question\, beyond the scope of the talk.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/langlands-duality-for-3-manifolds/
LOCATION:Virtual
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-Colloquium-09.29.21.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20210929T114800
DTEND;TZID=America/New_York:20210929T134800
DTSTAMP:20240301T093415Z
CREATED:20240214T090955Z
LAST-MODIFIED:20240301T093415Z
UID:10002610-1632916080-1632923280@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Oscillations in the thermal conductivity of a spin liquid*
DESCRIPTION:Title: Oscillations in the thermal conductivity of a spin liquid* \nAbstract: The layered honeycomb magnet alpha-RuCl3 orders below 7 K in a zigzag phase in zero field. An in-plane magnetic field H||a suppresses the zigzag order at 7 Tesla\, leaving a spin-disordered phase widely believed to be a quantum spin liquid (QSL) that extends to ~12 T. We have observed oscillations in the longitudinal thermal conductivity Kxx vs. H from 0.4 to 4 K. The oscillations are periodic in 1/H (with a break-in-slope at 7 T). The amplitude function is maximal in the QSL phase (7 –11.5 T). I will describe a benchmark for crystalline disorder\, the reproducibility and intrinsic nature of the oscillations\, and discuss implications for the QSL state. I will also show detailed data on the thermal Hall conductivity Kxy measured from 0.4 K to 10 K and comment on recent half-quantization results. \n*Czajka et al.\, Nature Physics 17\, 915 (2021). \nCollaborators: Czajka\, Gao\, Hirschberger\, Lampen Kelley\, Banerjee\, Yan\, Mandrus and Nagler.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/9-29-2021-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20210923T114700
DTEND;TZID=America/New_York:20210923T134700
DTSTAMP:20240301T093540Z
CREATED:20240214T091227Z
LAST-MODIFIED:20240301T093540Z
UID:10002612-1632397620-1632404820@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Applications of instantons\, sphalerons and instanton-dyons in QCD
DESCRIPTION:Title: Applications of instantons\, sphalerons and instanton-dyons in QCD \nAbstract: I start with a general map of gauge topology\, including monopoles\, instantons and instanton-dyons. Then comes reminder of the “topological landscape”\, the minimal energy gauge field configurations\, as a function of Chern-Simons number Ncs and r.m.s. size. It includes “valleys” at integer Ncs separated by mountain ridges. The meaning of instantons\, instanton-antiinstanton “streamlines” or thimbles\, and sphalerons are reminded\, together with some proposal to produce sphalerons at LHC and RHIC. \nApplications of instanton ensembles\, as a model of QCD vacuum\, are mostly related to their fermionic zero modes  and t’Hooft effective Lagrangian\, which explains explicit and spontaneous breaking of chiral symmetries. Recent applications are related with hadronic wave functions\, at rest and in the light front (LFWFs). Two application would be spin-dependent forces and the so called “flavor asymmetry of antiquark sea” of the nucleons. At temperatures comparable to deconfinement transition\, instantons get split into constituents called instanton-dyons. Studies of their ensemble explains both deconfinement and chiral transitions\, in ordinary and deformed QCD.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/9-23-2021-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20210923T090000
DTEND;TZID=America/New_York:20210923T100000
DTSTAMP:20240222T072551Z
CREATED:20240212T111100Z
LAST-MODIFIED:20240222T072551Z
UID:10002042-1632387600-1632391200@live-hu-cmsa-222.pantheonsite.io
SUMMARY:The number of n-queens configurations
DESCRIPTION:Speaker: Michael Simkin\, Harvard CMSA \nTitle: The number of n-queens configurations \nAbstract: The n-queens problem is to determine Q(n)\, the number of ways to place n mutually non-threatening queens on an n x n board. The problem has a storied history and was studied by such eminent mathematicians as Gauss and Polya. The problem has also found applications in fields such as algorithm design and circuit development. \nDespite much study\, until recently very little was known regarding the asymptotics of Q(n). We apply modern methods from probabilistic combinatorics to reduce understanding Q(n) to the study of a particular infinite-dimensional convex optimization problem. The chief implication is that (in an appropriate sense) for a~1.94\, Q(n) is approximately (ne^(-a))^n. Furthermore\, our methods allow us to study the typical “shape” of n-queens configurations.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/interdisciplinary-science-seminar/
LOCATION:Virtual
CATEGORIES:Interdisciplinary Science Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20210922T113300
DTEND;TZID=America/New_York:20210922T133300
DTSTAMP:20240301T094449Z
CREATED:20240214T091602Z
LAST-MODIFIED:20240301T094449Z
UID:10002615-1632310380-1632317580@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Symmetry types in QFT and the CRT theorem
DESCRIPTION:Title: Symmetry types in QFT and the CRT theorem \nAbstract: I will discuss ideas around symmetry and Wick rotation contained in joint work with Mike Hopkins (https://arxiv.org/abs/1604.06527). This includes general symmetry types for relativistic field theories and their Wick rotation.  I will then indicate how the basic CRT theorem works for general symmetry types\, focusing on the case of the pin groups.  In particular\, I expand on a subtlety first flagged by Greaves-Thomas.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/9-22-2021-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20210921T093000
DTEND;TZID=America/New_York:20210921T093000
DTSTAMP:20240304T060511Z
CREATED:20240214T050308Z
LAST-MODIFIED:20240304T060511Z
UID:10002536-1632216600-1632216600@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Surfacehedra and the Binary Positive Geometry of Particle and “String” Amplitudes
DESCRIPTION:Speaker: Nima Arkani-Hamed\, IAS \nTitle: Surfacehedra and the Binary Positive Geometry of Particle and “String” Amplitudes
URL:https://live-hu-cmsa-222.pantheonsite.io/event/9-21-2021-combinatorics-physics-and-probability-seminar/
LOCATION:Virtual
CATEGORIES:Combinatorics Physics and Probability
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20210917T185400
DTEND;TZID=America/New_York:20210917T195400
DTSTAMP:20240301T094616Z
CREATED:20240214T091836Z
LAST-MODIFIED:20240301T094616Z
UID:10002617-1631904840-1631908440@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Strong Coupling Theory of Magic-Angle Graphene: A Pedagogical Introduction
DESCRIPTION:Title: Strong Coupling Theory of Magic-Angle Graphene: A Pedagogical Introduction \nAbstract: In this talk\, I will review a recently developed strong coupling theory of magic-angle twisted bilayer graphene. An advantage of this approach is that a single formulation can capture both the insulating and superconducting states\, and with a few simplifying assumptions\, can be treated analytically. I begin by reviewing the electronic structure of magic angle graphene’s flat bands\, in a limit that exposes their peculiar band topology and geometry. I will show how similarities between the flat bands and the lowest Landau level can provide valuable insights into the effect of interactions and form the basis for an analytic treatment of the problem. At integer fillings\, this approach points to flavor ordered insulators\, which can be captured by a sigma-model in its ordered phase. Remarkably\, topological textures of the sigma model carry electric charge which enables the same theory to describe the doped phases away from integer filling. I will show how this approach can lead to superconductivity on disordering the sigma model\, and estimate the Tc for the superconductor. I will highlight the important role played by an effective super-exchange coupling both in pairing and in setting the effective mass of Cooper pairs. At the end\, I will show how this theory provides criteria to predict which multilayer graphene stacks are expected to superconduct including the recently discovered alternating twist trilayer platform.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/9-17-2021-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20210916T184700
DTEND;TZID=America/New_York:20210916T194700
DTSTAMP:20240301T094752Z
CREATED:20240214T092053Z
LAST-MODIFIED:20240301T094752Z
UID:10002619-1631818020-1631821620@live-hu-cmsa-222.pantheonsite.io
SUMMARY:The Hilbert Space of large N Chern-Simons matter theories
DESCRIPTION:Title: The Hilbert Space of large N Chern-Simons matter theories \nAbstract: We demonstrate that all known formulae for the thermal partition function for large N Chern Simons matter theory admit a simple Hilbert Space interpretation. In each case this quantity equals the partition function of an associated ungauged large $N$ matter theory with a particular local Lagrangian with one additional element: the Fock Space of this associated theory is projected down to the subspace of its WZW singlets. This projection\, in particular\,  implies the previously encountered `Bosonic Exclusion Principle’\, namely that no single particle state can be occupied by more than $k_B$ particles ($k_B$ is the Chern Simons level). Unlike its Gauss Law counterpart\, the WZW constraint does not trivialize in the large volume limit. However thermodynamics does simplify in this limit;  the final partition function reduces to a product of partition functions associated with each single particle state. These individual single particle state partition functions are a one parameter generalizations of their free boson and free fermion counterparts\, and reduce to the later at extreme values of the ‘t Hooft coupling. At generic values of the rank and the level the occupation statistics of each energy level is given by a $q$ deformation of the usual free formulae of Bose and Fermi statistics.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/9-16-2021-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20210915T184600
DTEND;TZID=America/New_York:20210915T194600
DTSTAMP:20240301T094948Z
CREATED:20240214T092313Z
LAST-MODIFIED:20240301T094948Z
UID:10002623-1631731560-1631735160@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Three-particle mechanism for pairing and superconductivity
DESCRIPTION:Title: Three-particle mechanism for pairing and superconductivity \nAbstract: I will present a new mechanism and an exact theory of electron pairing due to repulsive interaction in doped insulators. When the kinetic energy is small\, the dynamics of adjacent electrons on the lattice is strongly correlated. By developing a controlled kinetic energy expansion\, I will show that two doped charges can attract and form a bound state\, despite and because of the underlying repulsion. This attraction by repulsion is enabled by the virtual excitation of a third electron in the filled band. This three-particle pairing mechanism leads to a variety of novel phenomena at finite doping\, including spin-triplet superconductivity\, pair density wave\, BCS-BEC crossover and Feshbach resonance involving “trimers”. Possible realizations in moire materials\, ZrNCl and WTe2 will be discussed. \n[1] V. Crepel and L. Fu\, Science Advances 7\, eabh2233 (2021)\n[2] V. Crepel and L. Fu\, arXiv:2103.12060\n[3] K. Slagle and L. Fu\,  Phys. Rev. B 102\, 235423 (2020)
URL:https://live-hu-cmsa-222.pantheonsite.io/event/9-15-2021-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20210915T093000
DTEND;TZID=America/New_York:20210915T103000
DTSTAMP:20240501T205627Z
CREATED:20240214T044745Z
LAST-MODIFIED:20240501T205627Z
UID:10002533-1631698200-1631701800@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Hyperbolic Geometry and Quantum Invariants
DESCRIPTION:Speaker: Tian Yang (Texas A&M University) \nTitle: Hyperbolic Geometry and Quantum Invariants \nAbstract: There are two very different approaches to 3-dimensional topology\, the hyperbolic geometry following the work of Thurston and the quantum invariants following the work of Jones and Witten. These two approaches are related by a sequence of problems called the Volume Conjectures. In this talk\, I will explain these conjectures and present some recent joint works with Ka Ho Wong related to or benefited from this relationship.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/hyperbolic-geometry-and-quantum-invariants/
LOCATION:Virtual
CATEGORIES:Colloquium
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20210910T184400
DTEND;TZID=America/New_York:20210910T194400
DTSTAMP:20240301T095315Z
CREATED:20240214T092532Z
LAST-MODIFIED:20240301T095315Z
UID:10002624-1631299440-1631303040@live-hu-cmsa-222.pantheonsite.io
SUMMARY:More Exact Results in Gauge Theories: Confinement and Chiral Symmetry Breaking
DESCRIPTION:Title: More Exact Results in Gauge Theories: Confinement and Chiral Symmetry Breaking \nAbstract: In this follow-up to Hitoshi Murayama’s talk “Some Exact Results in QCD-like and Chiral Gauge Theories”\, I present a detailed analysis of the phases of $SO(N_c)$ gauge theory.\nStarting with supersymmetric $SO(N_c)$ with $N_F$ flavors\, we extrapolate to the non-supersymmetric limit using anomaly-mediated supersymmetry breaking (AMSB). Interestingly\, the abelian Coulomb and free magnetic phases do not survive supersymmetry breaking and collapse to a confining phase. This provided one of the first demonstrations of true confinement with chiral symmetry breaking in a non-SUSY theory.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/9-10-2021-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
END:VEVENT
END:VCALENDAR