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DTSTART;TZID=America/New_York:20230919T110000
DTEND;TZID=America/New_York:20230919T120000
DTSTAMP:20260504T220427
CREATED:20240223T101246Z
LAST-MODIFIED:20240223T101246Z
UID:10002846-1695121200-1695124800@cmsa.fas.harvard.edu
SUMMARY:Quantization of causal diamonds in 2+1 dimensional gravity
DESCRIPTION:General Relativity Seminar \nSpeaker: Rodrigo Silva\, University of Maryland \nTitle: Quantization of causal diamonds in 2+1 dimensional gravity \nAbstract: We develop the reduced phase space quantization of causal diamonds in $2+1$ dimensional gravity with a nonpositive cosmological constant. The system is defined as the domain of dependence of a spacelike topological disk with a fixed boundary metric. By solving the constraints in a constant-mean-curvature time gauge and removing all the spatial gauge redundancy\, we find that the phase space is the cotangent bundle of $Diff^+(S^1)/PSL(2\, \mathbb{R})$\, i.e.\, the group of orientation-preserving diffeomorphisms of the circle modulo the projective special linear subgroup. Classically\, the states correspond to causal diamonds embedded in $AdS_3$ (or $Mink_3$ if $\Lambda = 0$)\, with a fixed corner length\, that has the topological disk as a Cauchy surface. Because this phase space does not admit a global system of coordinates\, a generalization of the standard canonical (coordinate) quantization is required — in particular\, since the configuration space is a homogeneous space for a Lie group\, we apply Isham’s group-theoretic quantization scheme. The Hilbert space of the associated quantum theory carries an irreducible unitary representation of the $BMS_3$ group and can be realized by wavefunctions on a coadjoint orbit of Virasoro with labels in irreducible unitary representations of the corresponding little group. A surprising result is that the twist of the diamond boundary loop is quantized in terms of the ratio of the Planck length to the corner length. \n 
URL:https://cmsa.fas.harvard.edu/event/gr_91923/
CATEGORIES:General Relativity Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-GR-Seminar-09.19.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230919T123000
DTEND;TZID=America/New_York:20230919T133000
DTSTAMP:20260504T220427
CREATED:20240223T080443Z
LAST-MODIFIED:20240223T080443Z
UID:10002832-1695126600-1695130200@cmsa.fas.harvard.edu
SUMMARY:CMSA Q and A Seminar 9/19/2023
DESCRIPTION:Speakers: Dan Freed (Harvard Math and CMSA)\, Denis Auroux (Harvard Math)
URL:https://cmsa.fas.harvard.edu/event/cmsaqa_91923/
LOCATION:Common Room\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:CMSA Q&A Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230920T103000
DTEND;TZID=America/New_York:20230920T113000
DTSTAMP:20260504T220427
CREATED:20240223T104903Z
LAST-MODIFIED:20240223T104903Z
UID:10002851-1695205800-1695209400@cmsa.fas.harvard.edu
SUMMARY:Exact Results in Flat Band Hubbard Models
DESCRIPTION:Topological Quantum Matter Seminar \nSpeaker: Jonah Herzog-Arbeitman\, Princeton University \nTitle: Exact Results in Flat Band Hubbard Models \nAbstract: Flat bands\, like those in the kagome lattice or twisted bilayer graphene\, are a natural setting for studying strongly coupled physics since the interaction strength is the only energy scale in the problem. They can exhibit unconventional behavior in the multi-orbital case: the mean-field theory of flat band attractive Hubbard models shows the possibility of superconductivity even though the Fermi velocity of the bands is strictly zero. However\, it is not necessary to resort to this approximation. We demonstrate that the groundstates and low-energy excitations of a large class of attractive Hubbard models are exactly solvable\, offering a rare\, microscopic view of their physics. The solution reveals the importance of quantum geometry in escaping (some of) BCS phenomenology within a tractable and nontrivial strong coupling theory.
URL:https://cmsa.fas.harvard.edu/event/tqms_92023/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Topological Quantum Matter Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Topological-Seminar-09.20.23.docx-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230920T140000
DTEND;TZID=America/New_York:20230920T150000
DTSTAMP:20260504T220427
CREATED:20240227T083355Z
LAST-MODIFIED:20240227T083355Z
UID:10002873-1695218400-1695222000@cmsa.fas.harvard.edu
SUMMARY:The TinyStories Dataset: How Small Can Language Models Be And Still Speak Coherent
DESCRIPTION:New Technologies in Mathematics Seminar \nSpeaker: Ronen Eldan\, Microsoft Research \nTitle: The TinyStories Dataset: How Small Can Language Models Be And Still Speak Coherent \nAbstract: While generative language models exhibit powerful capabilities at large scale\, when either the model or the number of training steps is too small\, they struggle to produce coherent and fluent text: Existing models whose size is below a few billion parameters often do not generate coherent text beyond a few sentences. Hypothesizing that one of the main reasons for the strong reliance on size is the vast breadth and abundance of patterns in the datasets used to train those models\, this motivates the following question: Can we design a dataset that preserves the essential elements of natural language\, such as grammar\, vocabulary\, facts\, and reasoning\, but that is much smaller and more refined in terms of its breadth and diversity? \nIn this talk\, we introduce TinyStories\, a synthetic dataset of short stories that only contain words that 3 to 4-year-olds typically understand\, generated by GPT-3.5/4. We show that TinyStories can be used to train and analyze language models that are much smaller than the state-of-the-art models (below 10 million parameters)\, or have much simpler architectures (with only one transformer block)\, yet still produce fluent and consistent stories with several paragraphs that are diverse and have almost perfect grammar\, and demonstrate certain reasoning capabilities. We also show that the trained models are substantially more interpretable than larger ones\, as we can visualize and analyze the attention and activation patterns of the models\, and show how they relate to the generation process and the story content. We hope that TinyStories can facilitate the development\, analysis and research of language models\, especially for low-resource or specialized domains\, and shed light on the emergence of language capabilities in LMs. \n 
URL:https://cmsa.fas.harvard.edu/event/nt-92023/
LOCATION:Virtual
CATEGORIES:New Technologies in Mathematics Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-NTM-Seminar-09.20.2023.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230922T100000
DTEND;TZID=America/New_York:20230922T113000
DTSTAMP:20260504T220427
CREATED:20240223T095601Z
LAST-MODIFIED:20240223T095601Z
UID:10002845-1695376800-1695382200@cmsa.fas.harvard.edu
SUMMARY:Floquet codes\, automorphisms\, and quantum computation
DESCRIPTION:Quantum Matter Seminar \nSpeaker: Margarita Davydova (MIT) \nTitle: Floquet codes\, automorphisms\, and quantum computation \nAbstract: In this talk\, I will introduce a new kind of measurement-based quantum computation inspired by Floquet codes. In this model\, the quantum logical gates are implemented by short sequences of low-weight measurements which simultaneously encode logical information and enable error correction.  We introduce a new class of quantum error-correcting codes generalizing Floquet codes that achieve this\, which we call dynamic automorphism (DA) codes. \nAs in Floquet codes\, the instantaneous codespace of a DA code at any fixed point in time is that of a topological code. In this case\, the quantum computation can be viewed as a sequence of time-like domain walls implementing automorphisms of the topological order\, which can be understood in terms of reversible anyon condensation paths in a particular parent model.  This talk will introduce all of these concepts as well as provide a new perspective for thinking about Floquet codes. \nThe explicit examples that we construct\, which we call DA color codes\, can implement the full Clifford group of logical gates in 2+1d by two- and\, rarely three-body measurements. Using adaptive two-body measurements\, we can achieve a non-Clifford gate in 3+1d\, making the first step towards universal quantum computation in this model. \nThe talk is based on recent work with Nathanan Tantivasadakarn\, Shankar Balasubramanian\, and David Aasen [arxiv: 2307.10353].
URL:https://cmsa.fas.harvard.edu/event/qm_92223/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-09.22.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230922T120000
DTEND;TZID=America/New_York:20230922T130000
DTSTAMP:20260504T220427
CREATED:20240223T112106Z
LAST-MODIFIED:20240223T112106Z
UID:10002861-1695384000-1695387600@cmsa.fas.harvard.edu
SUMMARY:Modularity of Landau-Ginzburg Models
DESCRIPTION:Member Seminar \nSpeaker: Chuck Doran \nTitle: Modularity of Landau-Ginzburg Models \nAbstract:  Fano varieties are the basic building blocks of algebraic varieties.  Smooth Fano varieties have been classified in dimensions one (the projective line)\, two (del Pezzo surfaces)\, and three (Mori-Mukai classification).  What does Mirror Symmetry have to say about such classifications?  By studying the Landau-Ginzburg models mirror to smooth Fano threefolds we can transform the Mori-Mukai classification into an effective uniruledness result for moduli spaces of certain K3 and abelian surfaces.  This is joint work with Andrew Harder\, Ludmil Katzarkov\, Mikhail Ovcharenko\, and Victor Przjalkowski (arXiv:2307.15607). \n  \n 
URL:https://cmsa.fas.harvard.edu/event/member-seminar-92223/
LOCATION:Common Room\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Member Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230922T160000
DTEND;TZID=America/New_York:20230922T180000
DTSTAMP:20260504T220427
CREATED:20230904T063853Z
LAST-MODIFIED:20240710T192912Z
UID:10001124-1695398400-1695405600@cmsa.fas.harvard.edu
SUMMARY:CMSA/Math Fall Gathering
DESCRIPTION:Friday\, Sep 22\, 2023\n\n4:00 pm\n\nAll CMSA and Math affiliates are invited.
URL:https://cmsa.fas.harvard.edu/event/fallgathering2023/
LOCATION:Common Room\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Event
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230925T100000
DTEND;TZID=America/New_York:20230925T113000
DTSTAMP:20260504T220427
CREATED:20240222T090151Z
LAST-MODIFIED:20240222T090151Z
UID:10002792-1695636000-1695641400@cmsa.fas.harvard.edu
SUMMARY:Species Scale across String Moduli Spaces
DESCRIPTION:Algebraic Geometry in String Theory Seminar \n\nPre-talk Speaker: David Wu (Harvard Physics): 10:00-10:30 am \nSpeaker: Damian van de Heisteeg\, CMSA \n\nTitle: Species Scale across String Moduli Spaces \nAbstract: String theories feature a wide array of moduli spaces. We propose that the energy cutoff scale of these theories – the so-called species scale – can be determined through higher-curvature corrections. This species scale varies with the moduli; we use it both asymptotically to bound the diameter of the field space\, as well as in the interior to determine a “desert point” where it is maximized.
URL:https://cmsa.fas.harvard.edu/event/agst-92523/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Algebraic Geometry in String Theory Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230926T110000
DTEND;TZID=America/New_York:20230926T120000
DTSTAMP:20260504T220427
CREATED:20240223T104632Z
LAST-MODIFIED:20240813T160129Z
UID:10002850-1695726000-1695729600@cmsa.fas.harvard.edu
SUMMARY:Geometry at Strong coupling for amplitudes/Wilson loops
DESCRIPTION:General Relativity Seminar \nSpeaker: Lionel Mason (Oxford) \nTitle: Geometry at Strong coupling for amplitudes/Wilson loops \nAbstract: The amplitude/Wilson loop correspondence identifies planar N=4 super-Yang-Mills amplitudes with certain null polygonal Wilson loops at all the values of the coupling. At strong coupling this equates the amplitude/Wilson loop computed by Alday & Maldacena in terms of the area of a minimal surface in AdS_5. To do so they developed a `Y-system’ for computing the amplitude. This talk re-interprets their construction as providing the underlying twistor space for a hyperKahler structure on the corresponding space of kinematic data. In particular\, the area is given by a Kahler scalar for the pseudo-hyperkahler structure and satisfies a version of the Plebanski equations\, a well-known completely integrable system. This geometry encodes the properties of the space of kinematic data on which the amplitude depends as a cluster variety tying into its positive geometry and cluster variety structure. Similar constructures are possible for other cluster varieties corresponding to form factors and beyond.
URL:https://cmsa.fas.harvard.edu/event/gr_92623/
CATEGORIES:General Relativity Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-GR-Seminar-09.26.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230926T123000
DTEND;TZID=America/New_York:20230926T133000
DTSTAMP:20260504T220427
CREATED:20240223T081626Z
LAST-MODIFIED:20240223T081646Z
UID:10002835-1695731400-1695735000@cmsa.fas.harvard.edu
SUMMARY:CMSA Q and A Seminar 9/26/2023
DESCRIPTION:CMSA Q and A Seminar \nSpeakers: Michael Douglas (CMSA) and Mayuko Yamashita (Kyoto University) \nTopics: \nMichael Douglas: “What is non-commutative field theory?”\n\nMayuko Yamashita: “What is differential cohomology?”
URL:https://cmsa.fas.harvard.edu/event/cmsaqa_92623/
LOCATION:Common Room\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:CMSA Q&A Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230927T140000
DTEND;TZID=America/New_York:20230927T150000
DTSTAMP:20260504T220427
CREATED:20240227T082824Z
LAST-MODIFIED:20240227T082824Z
UID:10002872-1695823200-1695826800@cmsa.fas.harvard.edu
SUMMARY:Transformers for maths\, and maths for transformers
DESCRIPTION:New Technologies in Mathematics Seminar \nSpeaker: François Charton\, Meta AI \nTitle:  Transformers for maths\, and maths for transformers \nAbstract: Transformers can be trained to solve problems of mathematics. I present two recent applications\, in mathematics and physics: predicting integer sequences\, and discovering the properties of scattering amplitudes in a close relative of Quantum ChromoDynamics. \nProblems of mathematics can also help understand transformers. Using two examples from linear algebra and integer arithmetic\, I show that model predictions can be explained\, that trained models do not confabulate\, and that carefully choosing the training distributions can help achieve better\, and more robust\, performance. \n  \n  \n 
URL:https://cmsa.fas.harvard.edu/event/nt-92723/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:New Technologies in Mathematics Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-NTM-Seminar-09.27.2023.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230927T153000
DTEND;TZID=America/New_York:20230927T163000
DTSTAMP:20260504T220427
CREATED:20240223T112514Z
LAST-MODIFIED:20240223T112647Z
UID:10002862-1695828600-1695832200@cmsa.fas.harvard.edu
SUMMARY:Large deviations for the 3D dimer model
DESCRIPTION:Probability Seminar \nSpeaker: Catherine Wolfram (MIT) \nTitle: Large deviations for the 3D dimer model \nAbstract: A dimer tiling of Z^d is a collection of edges such that every vertex is covered exactly once. In 2000\, Cohn\, Kenyon\, and Propp showed that 2D dimer tilings satisfy a large deviations principle. In joint work with Nishant Chandgotia and Scott Sheffield\, we prove an analogous large deviations principle for dimers in 3D. A lot of the results for dimers in two dimensions use tools and exact formulas (e.g. the height function representation of a tiling or the Kasteleyn determinant formula) that are specific to dimension 2. In this talk\, I will try to give some intuition for why three dimensions is different from two\, explain how to formulate the large deviations principle in 3D\, show simulations\, and explain some of the ways that we use a smaller set of tools (e.g. Hall’s matching theorem or a double dimer swapping operation) in our arguments. \n 
URL:https://cmsa.fas.harvard.edu/event/probability-92723/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Probability Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Probability-Seminar-09.27.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230928T130000
DTEND;TZID=America/New_York:20230928T140000
DTSTAMP:20260504T220427
CREATED:20240223T072654Z
LAST-MODIFIED:20240223T072654Z
UID:10002827-1695906000-1695909600@cmsa.fas.harvard.edu
SUMMARY:Strongly driven mixtures and membranes: Out of equilibrium surprises 
DESCRIPTION:Active Matter Seminar\n\n\nSpeaker: Max Lavrentovich\, Worcester State University \nTitle: Strongly driven mixtures and membranes: Out of equilibrium surprises \nAbstract: The more prosaic cousin of active matter\, driven inactive matter\, is still full of unexpected phenomena. I will discuss two projects involving two seemingly mundane systems\, a phase-separating colloidal mixture and a lipid membrane\, which demonstrate counterintuitive properties when driven out of equilibrium. We will see that the phase separating mixture\, when driven by a uniform force\, develops (in simulations) an intriguing pattern with a characteristic length scale set by the magnitude of the drive. We will look at some theoretical approaches to understanding the pattern formation and possible experimental realizations. The membrane\, when driven by an oscillatory electric field\, develops (in experiments) a long-lived metastable state with a decreased capacitance and increased dissipation. This state may have implications for neuronal processing and memory formation.
URL:https://cmsa.fas.harvard.edu/event/am-92823/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Active Matter Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Active-Matter-Seminar-09.28.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230928T163000
DTEND;TZID=America/New_York:20230928T180000
DTSTAMP:20260504T220427
CREATED:20240221T112307Z
LAST-MODIFIED:20240813T161833Z
UID:10002780-1695918600-1695924000@cmsa.fas.harvard.edu
SUMMARY:Quantum field theory approach to quantum information
DESCRIPTION:Quantum Matter Seminar \nSpeaker: Cenke Xu (UCSB) \nTitle: Quantum field theory approach to quantum information \nAbstract: We apply the formalism of quantum field theory and Euclidean space-time path integral to investigate a class of quantum information problems. In particular\, we investigate quantum many-body systems under weak-measurement and decoherence. The Euclidean space-time path integral allows us to map this problem to a quantum field theory with (temporal) boundary or defects. We therefore investigate two types of quantum many-body systems with nontrivial boundary physics: quantum critical points\, and states with nontrivial topology\, such as Chern insulator and symmetry protected topological states. For example\, we demonstrate that a Wilson-Fisher quantum critical point can be driven into an “extraordinary-log” phase after weak-measurement. Another example is that\, we argue that a system with higher form symmetry may be driven to a self-dual phase transition under weak measurement.
URL:https://cmsa.fas.harvard.edu/event/qm_92823/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-09.28.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230929T120000
DTEND;TZID=America/New_York:20230929T130000
DTSTAMP:20260504T220427
CREATED:20240223T112516Z
LAST-MODIFIED:20240223T112516Z
UID:10002863-1695988800-1695992400@cmsa.fas.harvard.edu
SUMMARY:Moduli of vector bundles on curve and semiorthogonal decomposition
DESCRIPTION:Member Seminar \nSpeaker: Kai Xu (CMSA) \nTitle: Moduli of vector bundles on curve and semiorthogonal decomposition \nAbstract: In this talk we construct semiorthogonal decompositions of moduli of vector bundles on a curve into its symmetric powers. The essential ingredients in the proof include Borel-Weil-Bott theory for loop groups\, derived Schur-Weyl duality for current groups and derived Θ-stratification. \n 
URL:https://cmsa.fas.harvard.edu/event/member-seminar-92923/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Member Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230929T140000
DTEND;TZID=America/New_York:20230929T150000
DTSTAMP:20260504T220427
CREATED:20240223T103610Z
LAST-MODIFIED:20240223T103610Z
UID:10002848-1695996000-1695999600@cmsa.fas.harvard.edu
SUMMARY:Topological modular forms and heretoric string theory
DESCRIPTION:Special Seminar\n\n\n\n\n\nSpeaker: Mayuko Yamashita\, Kyoto University \n\nTitle: Topological modular forms and heretoric string theory \nAbstract: In this talk I will explain my works with Y. Tachikawa to study anomaly in heterotic string theory via homotopy theory\, especially the theory of Topological Modular Forms (TMF). TMF is an E-infinity ring spectrum which is conjectured by Stolz-Teichner to classify two-dimensional supersymmetric quantum field theories in physics. In the previous work (https://arxiv.org/abs/2108.13542)\, we proved the vanishing of anomalies in heterotic string theory mathematically by using TMF. \nFurthermore\, we have a recent update (https://arxiv.org/abs/2305.06196) on the previous work. Because of the vanishing result\, we can consider a secondary transformation of spectra\, which is shown to coincide with the Anderson self-duality morphism of TMF. This allows us to detect subtle torsion phenomena in TMF by differential-geometric ways\, and leads us to new conjectures on the relation between VOAs and TMF. \n\n 
URL:https://cmsa.fas.harvard.edu/event/ss_92923/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Special Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Special-Seminar-09.29.23-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20231002T103000
DTEND;TZID=America/New_York:20231002T113000
DTSTAMP:20260504T220427
CREATED:20240222T084421Z
LAST-MODIFIED:20240222T084421Z
UID:10002791-1696242600-1696246200@cmsa.fas.harvard.edu
SUMMARY:Motivic decomposition of moduli space from brane dynamics
DESCRIPTION:Algebraic Geometry in String Theory Seminar \n\n\nPre-talk Speaker: Kai Xu (CMSA): 10:00-10:30 am \n\nSpeaker: Kai Xu (CMSA) \nTitle: Motivic decomposition of moduli space from brane dynamics \nAbstract: Supersymmetric gauge theories encode deep structures in algebraic geometry\, and geometric engineering gives a powerful way to understand the underlying structures by string/M theory. In this talk we will see how the dynamics of M5 branes tell us about the motivic and semiorthogonal decompositions of moduli of bundles on curves.
URL:https://cmsa.fas.harvard.edu/event/agst-10223/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Algebraic Geometry in String Theory Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Algebraic-Geometry-in-String-Theory-10.02.2023.docx-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20231002T163000
DTEND;TZID=America/New_York:20231002T173000
DTSTAMP:20260504T220427
CREATED:20240227T095159Z
LAST-MODIFIED:20240227T095159Z
UID:10002874-1696264200-1696267800@cmsa.fas.harvard.edu
SUMMARY:Gravitational Instantons
DESCRIPTION:Speaker: Yu-Shen Lin (Boston University) \nTitle: Gravitational Instantons \nAbstract: Gravitational instantons were introduced by Hawking as building blocks of his Euclidean quantum gravity theory back in the 1970s. These are non-compact Calabi-Yau surfaces with L2 curvature and thus can be viewed as the non-compact analogue of K3 surfaces. K3 surfaces are 2-dimensional Calabi-Yau manifolds and are usually the testing stone before conquering the general Calabi-Yau problems. The moduli space of K3 surfaces and its compactification on their own form important problems in various branches in geometry. In this talk\, we will discuss the Torelli theorem of gravitational instantons\, how the cohomological invariants of a gravitational instanton determine them. As a consequence\, this leads to a description of the moduli space of gravitational instantons.
URL:https://cmsa.fas.harvard.edu/event/colloquium-10223/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Colloquium-10.02.2023.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20231003T110000
DTEND;TZID=America/New_York:20231003T120000
DTSTAMP:20260504T220427
CREATED:20240223T054715Z
LAST-MODIFIED:20240223T054715Z
UID:10002820-1696330800-1696334400@cmsa.fas.harvard.edu
SUMMARY:A Smooth Horizon without a Smooth Horizon
DESCRIPTION:General Relativity Seminar \nSpeaker: Chethan Krishnan (IISc Bangalore) \nTitle: A Smooth Horizon without a Smooth Horizon \nAbstract: I will talk about some work that is about to appear\, where we note one precise way in which the stretched horizon can simulate a smooth horizon. I will also make an effort to put things in some perspective (brickwalls\, fuzzballs\, Type I algebras\,…)
URL:https://cmsa.fas.harvard.edu/event/gr_10323/
CATEGORIES:General Relativity Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20231003T123000
DTEND;TZID=America/New_York:20231003T133000
DTSTAMP:20260504T220427
CREATED:20240223T082622Z
LAST-MODIFIED:20240223T082622Z
UID:10002836-1696336200-1696339800@cmsa.fas.harvard.edu
SUMMARY:CMSA Q and A Seminar 10/3/2023
DESCRIPTION:CMSA Q and A Seminar \nSpeakers: Dan Freed (Harvard Math & CMSA) and Dan Berwick-Evans (University of Illinois at Urbana-Champaign)\n\nTopics:\nDan Freed: What is framing anomaly? How is it different from other anomalies?\nDan Berwick-Evans: What is Atiyah-Singer index theorem?
URL:https://cmsa.fas.harvard.edu/event/cmsaqa_10323/
LOCATION:Common Room\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:CMSA Q&A Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20231004T103000
DTEND;TZID=America/New_York:20231004T113000
DTSTAMP:20260504T220427
CREATED:20240221T111722Z
LAST-MODIFIED:20240221T111849Z
UID:10002779-1696415400-1696419000@cmsa.fas.harvard.edu
SUMMARY:Dipolar and modulated symmetry protected topological phases
DESCRIPTION:<strong>Topological Quantum Matter Seminar</strong> \n<strong>Speaker:</strong> Ho Tat Lam\, MIT \n<strong>Title:</strong> Dipolar and modulated symmetry protected topological phases \n<strong>Abstract:</strong> Modulated symmetries are symmetries whose symmetry generators exhibit spatial modulations. We will discuss one-dimensional symmetry protected topological (SPT) phases protected by modulated symmetries. We will present a simple recipe for constructing modulated SPT models by generalizing the concept of decorated domain walls. We will then focus on the simplest modulated SPT protected by dipolar symmetries\, classify them using matrix product states and construct their response field theories using twisted finite tensor gauge theories.
URL:https://cmsa.fas.harvard.edu/event/tqms_10423/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Topological Quantum Matter Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Topological-Seminar-10.04.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20231006T120000
DTEND;TZID=America/New_York:20231006T130000
DTSTAMP:20260504T220427
CREATED:20240223T105546Z
LAST-MODIFIED:20240223T105621Z
UID:10002854-1696593600-1696597200@cmsa.fas.harvard.edu
SUMMARY:Random matrices and large deviations 
DESCRIPTION:Member Seminar \nSpeaker: Benjamin McKenna \nTitle: Random matrices and large deviations \nAbstract: We give a generalist overview of random matrices and their (a)typical behaviors. In recent years\, classical results have been complemented by a variety of new ones\, in both the math and physics literatures\, whose proofs leverage connections with special integrals over matrix groups. Some of these models exhibit interesting transition points\, whose motivating relationships to eigenvector (de)localization are not yet fully understood. Based on joint work with Jonathan Husson. \n 
URL:https://cmsa.fas.harvard.edu/event/member-seminar-10623/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Member Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20231010T110000
DTEND;TZID=America/New_York:20231010T120000
DTSTAMP:20260504T220427
CREATED:20240223T054233Z
LAST-MODIFIED:20240223T054233Z
UID:10002819-1696935600-1696939200@cmsa.fas.harvard.edu
SUMMARY:Tidal Squeezing of Black Holes
DESCRIPTION:General Relativity Seminar \nSpeaker: Maria Rodriguez (Utah) \nTitle: Tidal Squeezing of Black Holes \nAbstract: Recent developments indicate that Kerr black holes do not deform when perturbed by a static external gravitational field. Relying on hidden symmetries\, compelling progress has been achieved to explain that Love numbers for Kerr black holes vanish. How does the phenomenon of tidal squeezing manifest in broader contexts? An elementary presentation of dynamical tidal squeezing of Kerr black holes will be given.
URL:https://cmsa.fas.harvard.edu/event/gr_101023/
CATEGORIES:General Relativity Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-GR-Seminar-10.10.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20231010T123000
DTEND;TZID=America/New_York:20231010T133000
DTSTAMP:20260504T220427
CREATED:20240223T091026Z
LAST-MODIFIED:20240223T103936Z
UID:10002842-1696941000-1696944600@cmsa.fas.harvard.edu
SUMMARY:CMSA Q and A Seminar 10/10/23
DESCRIPTION:CMSA Q and A Seminar \nSpeakers: Dan Freed (Harvard Math and CMSA) and Sunghyuk Park (CMSA) \nTopics: \nDan Freed: What is Dijkgraaf-Witten theory? \nSunghyuk Park: What happened at the Clay Math Institute Workshop?
URL:https://cmsa.fas.harvard.edu/event/cmsaqa_101023/
LOCATION:Common Room\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:CMSA Q&A Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20231011T140000
DTEND;TZID=America/New_York:20231011T150000
DTSTAMP:20260504T220427
CREATED:20240223T114336Z
LAST-MODIFIED:20240223T114336Z
UID:10002868-1697032800-1697036400@cmsa.fas.harvard.edu
SUMMARY:LeanDojo: Theorem Proving with Retrieval-Augmented Language Models
DESCRIPTION:New Technologies in Mathematics Seminar \nSpeaker: Alex Gu\, MIT Dept. of EE&CS \nTitle: LeanDojo: Theorem Proving with Retrieval-Augmented Language Models \nAbstract: Large language models (LLMs) have shown promise in proving formal theorems using proof assistants such as Lean. However\, existing methods are difficult to reproduce or build on\, due to private code\, data\, and large compute requirements. This has created substantial barriers to research on machine learning methods for theorem proving. We introduce LeanDojo: an open-source Lean playground consisting of toolkits\, data\, models\, and benchmarks. LeanDojo extracts data from Lean and enables interaction with the proof environment programmatically. It contains fine-grained annotations of premises in proofs\, providing valuable data for premise selection: a key bottleneck in theorem proving. Using this data\, we develop ReProver (Retrieval-Augmented Prover): the first LLM-based prover that is augmented with retrieval for selecting premises from a vast math library. It is inexpensive and needs only one GPU week of training. Our retriever leverages LeanDojo’s program analysis capability to identify accessible premises and hard negative examples\, which makes retrieval much more effective. Furthermore\, we construct a new benchmark consisting of 96\,962 theorems and proofs extracted from Lean’s math library. It features a challenging data split requiring the prover to generalize to theorems relying on novel premises that are never used in training. We use this benchmark for training and evaluation\, and experimental results demonstrate the effectiveness of ReProver over non-retrieval baselines and GPT-4. We thus provide the first set of open-source LLM-based theorem provers without any proprietary datasets and release it under a permissive MIT license to facilitate further research. \n 
URL:https://cmsa.fas.harvard.edu/event/nt-101123-2/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:New Technologies in Mathematics Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-NTM-Seminar-10.11.2023.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20231011T163000
DTEND;TZID=America/New_York:20231011T180000
DTSTAMP:20260504T220427
CREATED:20240222T060902Z
LAST-MODIFIED:20240222T060902Z
UID:10002785-1697041800-1697047200@cmsa.fas.harvard.edu
SUMMARY:Non-invertible symmetries\, leptons\, quarks\, and why multiple generations
DESCRIPTION:Quantum Matter Seminar \nSpeaker: Seth Koren (Notre Dame) \nTitle: Non-invertible symmetries\, leptons\, quarks\, and why multiple generations \nAbstract: Generalized global symmetries are present in theories of particle physics\, and understanding their structure can give insight into these theories and UV completions thereof.  After discussing the generalized symmetries of the Standard Model\, we will go Beyond and show that the identification of a non-invertible symmetry of Z’ models of L_µ – L_τ reveals the existence of non-Abelian horizontal gauge theories which naturally produce exponentially small Dirac neutrino masses. Next we will uncover a subtler non-invertible symmetry in horizontal gauge theories of the quark sector which will lead us to a massless down-type quarks solution to strong CP in color-flavor unification. Intriguingly\, this theory works by virtue of the SM having the same numbers of colors and generations.
URL:https://cmsa.fas.harvard.edu/event/qm_101123/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QMMP-10.11.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20231012T130000
DTEND;TZID=America/New_York:20231012T140000
DTSTAMP:20260504T220427
CREATED:20240223T072135Z
LAST-MODIFIED:20240223T072135Z
UID:10002826-1697115600-1697119200@cmsa.fas.harvard.edu
SUMMARY:Contractility\, structure formation and fluctuations in active gels\, with and without molecular motors
DESCRIPTION:Active Matter Seminar\n\n\nSpeaker: Fred MacKintosh (Rice University) \nTitle: Contractility\, structure formation and fluctuations in active gels\, with and without molecular motors \nAbstract: Various processes in living cells depend on contractile forces that are often generated by myosin motors in concert with polar actin filaments. A textbook example of this is the actomyosin contractile ring that forms during cell division. Recent evidence\, however\, has begun to suggest alternate or redundant mechanisms that do not depend on myosin. Experiments on simplified\, reconstituted systems also point to contractility and structure formation in disordered\, apolar arrays of filaments. We propose a motor-free mechanism that can generate contraction in biopolymer networks without the need for motors such as myosin or polar filaments such as actin. This mechanism is based on active binding and unbinding of cross-linkers that breaks the principle of detailed balance\, together with the asymmetric force-extension response of semiflexible biopolymers. We discuss the resulting force-velocity relation and other implications of this\, as well as possible evidence for non-motor force generation.
URL:https://cmsa.fas.harvard.edu/event/am-101223/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Active Matter Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Active-Matter-Seminar-10.12.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20231013T120000
DTEND;TZID=America/New_York:20231013T130000
DTSTAMP:20260504T220427
CREATED:20240223T105131Z
LAST-MODIFIED:20240223T105527Z
UID:10002852-1697198400-1697202000@cmsa.fas.harvard.edu
SUMMARY:On the Breakdown of Einstein's Gravity
DESCRIPTION:Member Seminar \nSpeaker: Puskar Mondal (CMSA) \nTitle: On the Breakdown of Einstein’s Gravity \nAbstract: It is important to understand under which conditions\, the solutions of non-linear hyperbolic PDEs break down in finite time. In the context of Einstein’s gravity\, this is very closely tied to naked singularity formation and Penrose’s weak cosmic censorship conjecture. In this talk\, I will give sharp estimates on the relevant geometric entities that allow one to continue the solutions of Einstein’s equations indefinitely in the future in a ‘time’ direction without forming a naked singularity.
URL:https://cmsa.fas.harvard.edu/event/member-seminar-101323/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Member Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20231016T100000
DTEND;TZID=America/New_York:20231016T113000
DTSTAMP:20260504T220427
CREATED:20240222T075624Z
LAST-MODIFIED:20240222T075624Z
UID:10002790-1697450400-1697455800@cmsa.fas.harvard.edu
SUMMARY:Moduli of boundary polarized Calabi-Yau pairs
DESCRIPTION:Algebraic Geometry in String Theory Seminar \nPre-talk Speaker: Rosie Shen (Harvard): 10:00-10:30 am \nPre-talk Title: Introduction to the singularities of the MMP \n\nSpeaker: Dori Bejleri (Harvard Math & CMSA) \nTitle: Moduli of boundary polarized Calabi-Yau pairs \nAbstract: The theories of KSBA stability and K-stability furnish compact moduli spaces of general type pairs and Fano pairs respectively. However\, much less is known about the moduli theory of Calabi-Yau pairs. In this talk I will present an approach to constructing a moduli space of Calabi-Yau pairs which should interpolate between KSBA and K-stable moduli via wall-crossing.  I will explain how this approach can be used to construct projective moduli spaces of plane curve pairs. This is based on joint work with K. Ascher\, H. Blum\, K. DeVleming\, G. Inchiostro\, Y. Liu\, X. Wang. \n  \n 
URL:https://cmsa.fas.harvard.edu/event/agst-101623/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Algebraic Geometry in String Theory Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Algebraic-Geometry-in-String-Theory-10.16.2023.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20231016T140000
DTEND;TZID=America/New_York:20231016T150000
DTSTAMP:20260504T220427
CREATED:20240222T090812Z
LAST-MODIFIED:20240222T090812Z
UID:10002793-1697464800-1697468400@cmsa.fas.harvard.edu
SUMMARY:Breaking ergodicity: quantum scars and regular eigenstates
DESCRIPTION:Topological Quantum Matter Seminar \nSpeaker: Ceren Dag\, Harvard \nTitle: Breaking ergodicity: quantum scars and regular eigenstates \nAbstract: Quantum many-body scars (QMBS) consist of a few low-entropy eigenstates in an otherwise chaotic many-body spectrum and can weakly break ergodicity resulting in robust oscillatory dynamics. The notion of QMBS follows the original single-particle scars introduced within the context of quantum billiards\, where scarring manifests in the form of a quantum eigenstate concentrating around an underlying classical unstable periodic orbit (UPO). A direct connection between these notions remains an outstanding problem. Here\, we study a many-body spinor condensate that\, owing to its collective interactions\, is amenable to the diagnostics of scars. We characterize the system’s rich dynamics\, spectrum\, and phase space\, consisting of both regular and chaotic states. The former are low in entropy\, violate the Eigenstate Thermalization Hypothesis (ETH)\, and can be traced back to integrable effective Hamiltonians\, whereas most of the latter are scarred by the underlying semiclassical UPOs\, while satisfying ETH. We outline an experimental proposal to probe our theory in trapped spin-1 Bose-Einstein condensates. If time permits\, I will also mention our latest efforts in introducing spatial dimension to this model with a true semiclassical limit\, and how quantum scars persist to exist in a many-body system. Reference: arXiv 2306.10411\, in peer review.
URL:https://cmsa.fas.harvard.edu/event/tqms_101623/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Topological Quantum Matter Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Topological-Seminar-10.16.23.docx-1.png
END:VEVENT
END:VCALENDAR