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X-WR-CALDESC:Events for CMSA
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BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220426T093000
DTEND;TZID=America/New_York:20220426T103000
DTSTAMP:20240304T061555Z
CREATED:20230825T080553Z
LAST-MODIFIED:20240304T061555Z
UID:10001296-1650965400-1650969000@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Modularity of mirror families of log Calabi–Yau surfaces
DESCRIPTION:Abstract:   In “Mirror symmetry for log Calabi–Yau surfaces I\,” given a smooth log Calabi–Yau surface pair (Y\,D)\, Gross–Hacking–Keel constructed its mirror family as the spectrum of an explicit algebra whose structure coefficients are determined by the enumerative geometry of (Y\,D). As a follow-up of the work of Gross–Hacking–Keel\, when (Y\,D) is positive\, we prove the modularity of the mirror family as the universal family of log Calabi-Yau surface pairs deformation equivalent to (Y\,D) with at worst du Val singularities. As a corollary\, we show that the ring of regular functions of a smooth affine log Calabi–Yau surface has a canonical basis of theta functions. The key step towards the proof of the main theorem is the application of the tropical construction of singular cycles and explicit formulas of period integrals given in the work of Helge–Siebert. This is joint work with Jonathan Lai.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/modularity-of-mirror-families-of-log-calabi-yau-surfaces/
LOCATION:Virtual
CATEGORIES:Algebraic Geometry in String Theory Seminar
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-Algebraic-Geometry-in-String-Theory-04.26.2022.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220422T093000
DTEND;TZID=America/New_York:20220422T230000
DTSTAMP:20250328T200643Z
CREATED:20230706T180541Z
LAST-MODIFIED:20250328T200643Z
UID:10000096-1650619800-1650668400@live-hu-cmsa-222.pantheonsite.io
SUMMARY:CMSA/Tsinghua Math-Science Literature Lecture: Three Introductory Lectures on Game Theory for Mathematicians: Auction Theory
DESCRIPTION:Eric Maskin (Harvard University) Three Introductory Lectures on Game Theory for Mathematicians \nApril 22\, 2022 | 9:30 – 11:00 am ET \nTitle: Auction Theory \nAbstract: Equivalences among four standard auctions: the high-bid auction (the high bidder wins and pays her bid); the second-bid auction (the high bidder wins and pays the second-highest bid); the Dutch auction (the auctioneer lowers the price successively until some bidder is willing to pay); and the English auction (bidders raise their bids successively until no one wants to bid higher). \nTalk chairs: Scott Kominers\, Sergiy Verstyuk \nSLIDES | VIDEO Answers to Questions from Talks 2 and 3
URL:https://live-hu-cmsa-222.pantheonsite.io/event/maskin_gametheory2022_3/
LOCATION:Virtual
CATEGORIES:Math Science Literature Lecture Series,Public Lecture,Special Lectures
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/Mathlit_MASKIN-1583x2048-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220420T093000
DTEND;TZID=America/New_York:20220420T110000
DTSTAMP:20250328T200302Z
CREATED:20230706T180319Z
LAST-MODIFIED:20250328T200302Z
UID:10000095-1650447000-1650452400@live-hu-cmsa-222.pantheonsite.io
SUMMARY:CMSA/Tsinghua Math-Science Literature Lecture: Three Introductory Lectures on Game Theory for Mathematicians: Mechanism Design
DESCRIPTION:Eric Maskin (Harvard University) Three Introductory Lectures on Game Theory for Mathematicians \nApril 20\, 2022 | 9:30 – 11:00 am ET \nTitle: Mechanism Design \nAbstract: Given a social goal\, under what circumstances can we design a game to achieve that goal? \nTalk chairs: Scott Kominers\, Sergiy Verstyuk \nSLIDES | VIDEO
URL:https://live-hu-cmsa-222.pantheonsite.io/event/maskin_gametheory2022_2/
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/Mathlit_MASKIN-1583x2048-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220419T093000
DTEND;TZID=America/New_York:20220419T103000
DTSTAMP:20240304T061057Z
CREATED:20230825T080357Z
LAST-MODIFIED:20240304T061057Z
UID:10001295-1650360600-1650364200@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Equivariant Verlinde algebra and quantum K-theory of the moduli space of vortices
DESCRIPTION:Abstract:  In studying complex Chern-Simons theory on a Seifert manifold\, Gukov-Pei proposed an equivariant Verlinde formula\, a one-parameter deformation of the celebrated Verlinde formula. It computes\, among many things\, the graded dimension of the space of holomorphic sections of (powers of) a natural determinant line bundle over the Hitchin moduli space. Gukov-Pei conjectured that the equivariant Verlinde numbers are equal to the equivariant quantum K-invariants of a non-compact (Kahler) quotient space studied by Hanany-Tong. \nIn this talk\, I will explain the setup of this conjecture and its proof via wall-crossing of moduli spaces of (parabolic) Bradlow-Higgs triples. It is based on work in progress with Wei Gu and Du Pei.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/equivariant-verlinde-algebra-and-quantum-k-theory-of-the-moduli-space-of-vortices/
LOCATION:Virtual
CATEGORIES:Algebraic Geometry in String Theory Seminar
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-Algebraic-Geometry-in-String-Theory-04.19.2022.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220418T130000
DTEND;TZID=America/New_York:20220418T140000
DTSTAMP:20240301T072639Z
CREATED:20230730T181614Z
LAST-MODIFIED:20240301T072639Z
UID:10001149-1650286800-1650290400@live-hu-cmsa-222.pantheonsite.io
SUMMARY:4/18/2022 Swampland Seminar
DESCRIPTION:Open mic Swampland Discussion \nTopic: Cobordism
URL:https://live-hu-cmsa-222.pantheonsite.io/event/4-18-2022-swampland-seminar/
LOCATION:Virtual
CATEGORIES:Swampland Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220418T093000
DTEND;TZID=America/New_York:20220418T110000
DTSTAMP:20250328T200252Z
CREATED:20230706T180022Z
LAST-MODIFIED:20250328T200252Z
UID:10000094-1650274200-1650279600@live-hu-cmsa-222.pantheonsite.io
SUMMARY:CMSA/Tsinghua Math-Science Literature Lecture: Three Introductory Lectures on Game Theory for Mathematicians: Game Theory Basics and Classical Existence Theorems
DESCRIPTION:Eric Maskin (Harvard University) Three Introductory Lectures on Game Theory for Mathematicians \nApril 18\, 2022 | 9:30 – 11:00 am ET \nTitle: Game Theory Basics and Classical Existence Theorems \nAbstract: Games in extensive and normal form. Equilibrium existence theorems by Nash\, von Neumann\, and Zermelo \nTalk chairs: Scott Kominers\, Sergiy Verstyuk \nSLIDES | VIDEO \n 
URL:https://live-hu-cmsa-222.pantheonsite.io/event/maskin_gametheory2022_1/
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/Mathlit_MASKIN-1583x2048-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220414T093000
DTEND;TZID=America/New_York:20220414T110000
DTSTAMP:20240813T162915Z
CREATED:20240214T102053Z
LAST-MODIFIED:20240813T162915Z
UID:10002666-1649928600-1649934000@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Cancellation of the vacuum energy and Weyl anomaly in the standard model\, and a two-sheeted\, CPT-symmetric universe
DESCRIPTION:Youtube video \n  \n\n\nAbstract: I will explain a mechanism to cancel the vacuum energy and both terms in the Weyl anomaly in the standard model of particle physics\, using conformally-coupled dimension-zero scalar fields.  Remarkably\, given the standard model gauge group SU(3)xSU(2)xU(1)\, the cancellation requires precisely 48 Weyl spinors — i.e. three generations of standard model fermions\, including right-handed neutrinos.  Moreover\, the scalars possess a scale-invariant power spectrum\, suggesting a new explanation for the observed primordial density perturbations in cosmology (without the need for inflation). \nAs context\, I will also introduce a related cosmological picture in which this cancellation mechanism plays an essential role.  Our universe seems to be dominated by radiation at early times\, and positive vacuum energy at late times.  Taking the symmetry and analyticity properties of such a universe seriously suggests a picture in which spacetime has two sheets\, related by a symmetry that\, in turn\, selects a preferred (CPT-symmetric) vacuum state for the quantum fields that live on the spacetime.  This line of thought suggests new explanations for a number of observed properties of the universe\, including: its homogeneity\, isotropy and flatness; the arrow of time; several properties of the primordial perturbations; and the nature of dark matter (which\, in this picture\, is a right-handed neutrino\, radiated from the early universe like Hawking radiation from a black hole).  It also makes a number of testable predictions. \n(Based on recent\, and ongoing\, work with Neil Turok: arXiv:1803.08928\, arXiv:2109.06204\, arXiv:2110.06258\, arXiv:2201.07279.)
URL:https://live-hu-cmsa-222.pantheonsite.io/event/4-14-2022-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/jpeg:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-QMMP-Seminar-04.14.22-1583x2048-1-1.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220414T093000
DTEND;TZID=America/New_York:20220414T103000
DTSTAMP:20240301T112943Z
CREATED:20240214T083016Z
LAST-MODIFIED:20240301T112943Z
UID:10002589-1649928600-1649932200@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Global existence and stability of de Sitter-like solutions to the Einstein-Yang-Mills equations in spacetime dimensions n≥4
DESCRIPTION:Abstract: In this talk\, we briefly introduce our recent work on establishing the global existence and stability to the future of non-linear perturbation of de Sitter-like solutions to the Einstein-Yang-Mills system in n≥4 spacetime dimension. This generalizes Friedrich’s (1991) Einstein-Yang-Mills stability results in dimension n=4 to all higher dimensions. This is a joint work with Todd A. Oliynyk and Jinhua Wang.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/4-14-2022-general-relativity-seminar/
LOCATION:Virtual
CATEGORIES:General Relativity Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220413T203000
DTEND;TZID=America/New_York:20220413T220000
DTSTAMP:20240301T063645Z
CREATED:20240214T102340Z
LAST-MODIFIED:20240301T063645Z
UID:10002668-1649881800-1649887200@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Why is the mission impossible? Decoupling the mirror Ginsparg-Wilson fermions in the lattice models for two-dimensional abelian chiral gauge theories
DESCRIPTION:Youtube Video \nAbstract: It has been known that the four-dimensional abelian chiral gauge theories of an anomaly-free set of Wely fermions can be formulated on the lattice preserving the exact gauge invariance and the required locality property in the framework of the Ginsparg- Wilson relation. This holds true in two dimensions. However\, in the related formulation including the mirror Ginsparg-Wilson fermions\, it has been argued that the mirror fermions do not decouple: in the 3450 model with Dirac- and Majorana-Yukawa couplings to XY-spin field\, the two- point vertex function of the (external) gauge field in the mirror sector shows a singular non-local behavior in the so-called ParaMagnetic Strong-coupling(PMS) phase. \nWe re-examine why the attempt seems a “Mission: Impossible” in the 3450 model. We point out that the effective operators to break the fermion number symmetries (’t Hooft operators plus others) in the mirror sector do not have sufficiently strong couplings even in the limit of large Majorana-Yukawa couplings. We also observe that the type of Majorana-Yukawa term considered there is singular in the large limit due to the nature of the chiral projection of the Ginsparg-Wilson fermions\, but a slight modification without such singularity is allowed by virtue of the very nature. \nWe then consider a simpler four-flavor axial gauge model\, the 14(-1)4 model\, in which the U(1)A gauge and Spin(6)( SU(4)) global symmetries prohibit the bilinear terms\, but allow the quartic terms to break all the other continuous mirror-fermion symmetries. This model in the weak gauge-coupling limit is related to the eight-flavor Majorana Chain with a reduced SO(6)xSO(2) symmetry in Euclidean path-integral formulation. We formulate the model so that it is well-behaved and simplified in the strong-coupling limit of the quartic operators. Through Monte-Carlo simulations in the weak gauge-coupling limit\, we show a numerical evidence that the two-point vertex function of the gauge field in the mirror sector shows a regular local behavior. \nFinally\, by gauging a U(1) subgroup of the U(1)A× Spin(6)(SU(4)) of the previous model\, we formulate the 21(−1)3 chiral gauge model and argue that the induced effective action in the mirror sector satisfies the required locality property. This gives us “A New Hope” for the mission to be accomplished.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/4-13-2022-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/jpeg:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-QMMP-Seminar-04.13.22-1583x2048-1.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220412T115800
DTEND;TZID=America/New_York:20220412T125800
DTSTAMP:20240304T061648Z
CREATED:20230825T080118Z
LAST-MODIFIED:20240304T061648Z
UID:10001294-1649764680-1649768280@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Applications of Higher Determinant Map
DESCRIPTION:Abstract: In this talk I will explain the construction of a determinant map for Tate objects and two applications: (i) to construct central extensions of iterated loop groups and (ii) to produce a determinant theory on certain ind-schemes. For that I will introduce some aspects of the theory of Tate objects in a couple of contexts.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/applications-of-higher-determinant-map/
LOCATION:Virtual
CATEGORIES:Algebraic Geometry in String Theory Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220411T100000
DTEND;TZID=America/New_York:20220411T110000
DTSTAMP:20240301T072853Z
CREATED:20230730T181035Z
LAST-MODIFIED:20240301T072853Z
UID:10001148-1649671200-1649674800@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Type IIB flux compactifications with $h^{1\,1}=0$
DESCRIPTION:Abstract: We revisit type IIB flux compactification that are mirror dual to type IIA on rigid Calabi-Yau manifolds. We find a variety of interesting new solutions\, like fully stabilized Minkowski vacua and infinite families of AdS$_4$ solutions with arbitrarily large numbers of spacetime filling D3 branes. We discuss how these solutions fit into the web of swampland conjectures.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/4-11-2021-swampland-seminar/
LOCATION:Virtual
CATEGORIES:Swampland Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220408T084500
DTEND;TZID=America/New_York:20220408T101500
DTSTAMP:20240301T105121Z
CREATED:20240214T084325Z
LAST-MODIFIED:20240301T105121Z
UID:10002595-1649407500-1649412900@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Synthetic Regression Discontinuity: Estimating Treatment Effects using Machine Learning
DESCRIPTION:Speaker: Jörn Boehnke \nTitle: Synthetic Regression Discontinuity: Estimating Treatment Effects using Machine Learning \nAbstract:  In the standard regression discontinuity setting\, treatment assignment is based on whether a unit’s observable score (running variable) crosses a known threshold.  We propose a two-stage method to estimate the treatment effect when the score is unobservable to the econometrician while the treatment status is known for all units.  In the first stage\, we use a statistical model to predict a unit’s treatment status based on a continuous synthetic score.  In the second stage\, we apply a regression discontinuity design using the predicted synthetic score as the running variable to estimate the treatment effect on an outcome of interest.  We establish conditions under which the method identifies the local treatment effect for a unit at the threshold of the unobservable score\, the same parameter that a standard regression discontinuity design with known score would identify. We also examine the properties of the estimator using simulations\, and propose the use machine learning algorithms to achieve high prediction accuracy.  Finally\, we apply the method to measure the effect of an investment grade rating on corporate bond prices by any of the three largest credit ratings agencies.  We find an average 1% increase in the prices of corporate bonds that received an investment grade as opposed to a non-investment grade rating.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/4-8-2022-member-seminar/
LOCATION:Virtual
CATEGORIES:Member Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220407T093000
DTEND;TZID=America/New_York:20220407T110000
DTSTAMP:20240301T063834Z
CREATED:20240214T102601Z
LAST-MODIFIED:20240301T063834Z
UID:10002669-1649323800-1649329200@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Lattice Gauge Theory View of Toric Codes\, X-cube\, and More
DESCRIPTION:Youtube Video \n  \nAbstract: Exactly solvable spin models such as toric codes and X-cube model have heightened our understanding of spin liquids and topological matter in two and three dimensions. Their exact solvability\, it turns out\, is rooted in the existence of commuting generators in their parent lattice gauge theory (LGT). We can understand the toric codes as Higgsed descendants of the rank-1 U(1) LGT in two and three dimensions\, and the X-cube model as that of rank-2 U(1) LGT in three dimensions. Furthermore\, the transformation properties of the gauge fields in the respective LGT is responsible for\, and nearly determines the structure of the effective field theory (EFT) of the accompanying matter fields. We show how to construct the EFT of e and m particles in the toric codes and of fractons and lineons in the X-cube model by following such an idea. Recently we proposed some stabilizer Hamiltonians termed rank-2 toric code (R2TC) and F3 model (3D). We will explain what they are\, and construct their EFTs using the gauge principle as guidance. The resulting field theory of the matter fields are usually highly interacting and exhibit unusual conservation laws. Especially for the R2TC\, we demonstrate the existence of what we call the “dipolar braiding statistics” and outline the accompanying field theory which differs from the usual BF field theory of anyon braiding. \nReferences:\n[1] “Model for fractions\, fluxons\, and free verte excitations”\, JT Kim\, JH Han\, Phys. Rev. B 104\, 115128 (2021)\n[1] “Rank-2 toric code in two dimensions”\, YT Oh\, JT Kim\, EG Moon\, JH Han\, Phys. Rev. B 105\, 045128 (2022)\n[2] “Effective field theory for the exactly solvable stabilizer spin models”\, JT Kim\, YT Oh\, JH Han\, in preparation.\n[3] “Effective field theory of dipolar braiding statistics in two dimensions”\, YT Oh\, JT Kim\, JH Han\, in preparation.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/4-7-2022-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/jpeg:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-QMMP-04.07.2022-1583x2048-1.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220406T213000
DTEND;TZID=America/New_York:20220406T223000
DTSTAMP:20240301T112919Z
CREATED:20240214T080706Z
LAST-MODIFIED:20240301T112919Z
UID:10002581-1649280600-1649284200@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Gopakumar-Vafa type invariants of holomorphic symplectic 4-folds
DESCRIPTION:Abstract: Gromov-Witten invariants of holomorphic symplectic 4-folds vanish and one can consider the corresponding reduced theory. In this talk\, we will explain a definition of Gopakumar-Vafa type invariants for such a reduced theory. These invariants are conjectured to be integers and have alternative interpretations using sheaf theoretic moduli spaces. Our conjecture is proved for the product of two K3 surfaces\, which naturally leads to a closed formula of Fujiki constants of Chern classes of tangent bundles of Hilbert schemes of points on K3 surfaces. On a very general holomorphic symplectic 4-folds of K3^[2] type\, our conjecture provides a Yau-Zaslow type formula for the number of isolated genus 2 curves of minimal degree. Based on joint works with Georg Oberdieck and Yukinobu Toda.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/4-5-2022-joint-harvard-cuhk-ymsc-differential-geometry-seminar/
LOCATION:Virtual
CATEGORIES:Joint Harvard-CUHK-YMSC Differential Geometry
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/20220406_Yalong-CAO_poster.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220406T103000
DTEND;TZID=America/New_York:20220406T120000
DTSTAMP:20240301T064048Z
CREATED:20240214T102826Z
LAST-MODIFIED:20240301T064048Z
UID:10002671-1649241000-1649246400@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Late time von Neumann entropy and measurement-induced phase transition
DESCRIPTION:Youtube Video \n  \nAbstract: Characterizing many-body entanglement is one of the most important problems in quantum physics. We present our studies on the steady state von Neumann entropy and its transition in Brownian SYK models. For unitary evolution\, we show that the correlations between different replicas account for the Page curve at late time\, and a permutation group structure emerges in the large-N calculation. In the presence of measurements\, we find a transition of von Neumann entropy from volume-law to area-law by increasing the measurement rate. We show that a proper replica limit can be taken\, which shows that the transition occurs at the point of replica symmetry breaking.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/4-6-2022-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/jpeg:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-QMMP-04.06.2022-1583x2048-1.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220405T093000
DTEND;TZID=America/New_York:20220405T103000
DTSTAMP:20240304T082856Z
CREATED:20230825T075918Z
LAST-MODIFIED:20240304T082856Z
UID:10001293-1649151000-1649154600@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Regularized integrals on Riemann surfaces and correlations functions in 2d chiral CFTs
DESCRIPTION:Abstract: I will report a recent approach of regularizing divergent integrals on configuration spaces of Riemann surfaces\, introduced by Si Li and myself in arXiv:2008.07503\, with an emphasis on genus one cases where modular forms arise naturally. I will then talk about some applications in studying correlation functions in 2d chiral CFTs\, holomorphic anomaly equations\, etc. If time permits\, I will also mention a more algebraic formulation of this notion of regularized integrals in terms of mixed Hodge structures. \nThe talk is partially based on joint works with Si Li.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/regularized-integrals-on-riemann-surfaces-and-correlations-functions-in-2d-chiral-cfts/
LOCATION:Virtual
CATEGORIES:Algebraic Geometry in String Theory Seminar
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-Algebraic-Geometry-in-String-Theory-04.05.2022.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220404T100000
DTEND;TZID=America/New_York:20220404T230000
DTSTAMP:20240301T073634Z
CREATED:20230730T180720Z
LAST-MODIFIED:20240301T073634Z
UID:10001147-1649066400-1649113200@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Causality constraints on corrections to Einstein gravity
DESCRIPTION:Swampland Seminar \nSpeakers: Simon Caron-Huot (McGill University) and Julio Parra (Caltech) \n\n\nTitle: Causality constraints on corrections to Einstein gravity \n\nAbstract: We study constraints from causality and unitarity on 2→2 graviton scattering in four-dimensional weakly-coupled effective field theories. Together\, causality and unitarity imply dispersion relations that connect low-energy observables to high-energy data. Using such dispersion relations\, we derive two-sided bounds on gravitational Wilson coefficients in terms of the mass M of new higher-spin states. Our bounds imply that gravitational interactions must shut off uniformly in the limit G→0\, and prove the scaling with M expected from dimensional analysis (up to an infrared logarithm). We speculate that causality\, together with the non-observation of gravitationally-coupled higher-spin states at colliders\, severely restricts modifications to Einstein gravity that could be probed by experiments in the near future.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/4-5-2022-swampland-seminar/
LOCATION:Virtual
CATEGORIES:Swampland Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220401T090000
DTEND;TZID=America/New_York:20220401T103000
DTSTAMP:20240301T110938Z
CREATED:20240214T084536Z
LAST-MODIFIED:20240301T110938Z
UID:10002596-1648803600-1648809000@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Diffusive growth sourced by topological defects
DESCRIPTION:Member Seminar \nSpeaker: Farzan Vafa \nTitle: Diffusive growth sourced by topological defects \nAbstract: In this talk\, we develop a minimal model of morphogenesis of a surface where the dynamics of the intrinsic geometry is diffusive growth sourced by topological defects. We show that a positive (negative) defect can dynamically generate a cone (hyperbolic cone). We analytically explain features of the growth profile as a function of position and time\, and predict that in the presence of a positive defect\, a bump forms with height profile h(t) ~ t^(1/2) for early times t. To incorporate the effect of the mean curvature\, we exploit the fact that for axisymmetric surfaces\, the extrinsic geometry can be deduced entirely by the intrinsic geometry. We find that the resulting stationary geometry\, for polar order and small bending modulus\, is a deformed football.\nWe apply our framework to various biological systems. In an ex-vivo setting of cultured murine neural progenitor cells\, we show that our framework is consistent with the observed cell accumulation at positive defects and depletion at negative defects. In an in-vivo setting\, we show that the defect configuration consisting of a bound +1 defect state\, which is stabilized by activity\, surrounded by two -1/2 defects can create a stationary ring configuration of tentacles\, consistent with observations of a basal marine invertebrate Hydra
URL:https://live-hu-cmsa-222.pantheonsite.io/event/4-1-2022-member-seminar/
LOCATION:Virtual
CATEGORIES:Member Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220330T140000
DTEND;TZID=America/New_York:20220330T150000
DTSTAMP:20240515T202223Z
CREATED:20230808T183529Z
LAST-MODIFIED:20240515T202223Z
UID:10001209-1648648800-1648652400@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Memorizing Transformers
DESCRIPTION:Speaker: Yuhuai Wu\, Stanford and Google \nTitle: Memorizing Transformers \nAbstract: Language models typically need to be trained or fine-tuned in order to acquire new knowledge\, which involves updating their weights. We instead envision language models that can simply read and memorize new data at inference time\, thus acquiring new knowledge immediately. In this talk\, I will discuss how we extend language models with the ability to memorize the internal representations of past inputs. We demonstrate that an approximate NN lookup into a non-differentiable memory of recent (key\, value) pairs improves language modeling across various benchmarks and tasks\, including generic webtext (C4)\, math papers (arXiv)\, books (PG-19)\, code (Github)\, as well as formal theorems (Isabelle). We show that the performance steadily improves when we increase the size of memory up to 262K tokens. We also find that the model is capable of making use of newly defined functions and theorems during test time.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/3-30-2022-new-technologies-in-mathematics-seminar/
LOCATION:Virtual
CATEGORIES:New Technologies in Mathematics Seminar
ATTACH;FMTTYPE=image/jpeg:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-NTM-Seminar-03.30.2022-1583x2048-1.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220324T130000
DTEND;TZID=America/New_York:20220324T142000
DTSTAMP:20240122T085257Z
CREATED:20230824T173250Z
LAST-MODIFIED:20240122T085257Z
UID:10001309-1648126800-1648131600@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Topological defects drive layer formation in gliding bacteria colonies
DESCRIPTION:Abstract: The developmental cycle of Myxococcus xanthus involves the coordination of many hundreds of thousands of cells aggregating to form mounds known as fruiting bodies. This aggregation process begins with the sequential formation of more and more cell layers. Using three-dimensional confocal imaging we study this layer formation process by observing the formation of holes and second layers within a base monolayer of M xanthus cells. We find that cells align with each other over the majority of the monolayer forming an active nematic liquid crystal with defect point where cell alignment is undefined. We find that new layers and holes form at positive and negative topological defects respectively. We model the cell layer using hydrodynamic modeling and find that this layer and hole formation process is driven by active nematic forces through cell motility and anisotropic substrate friction.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/topological-defects-drive-layer-formation-in-gliding-bacteria-colonies/
LOCATION:Virtual
CATEGORIES:Active Matter Seminar
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-Active-Matter-Seminar-03.24.22.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220318T093000
DTEND;TZID=America/New_York:20220318T103000
DTSTAMP:20240301T111106Z
CREATED:20240214T084936Z
LAST-MODIFIED:20240301T111106Z
UID:10002599-1647595800-1647599400@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Moduli Space of Metric SUSY Graphs
DESCRIPTION:Member Seminar \nSpeaker: Yingying Wu \nTitle: Moduli Space of Metric SUSY Graphs \nAbstract: SUSY curves are algebraic curves with additional supersymmetric or supergeometric structures. In this talk\, I will present the construction of dual graphs of SUSY curves with Neveu–Schwarz and Ramond punctures. Then\, I will introduce the concept of the metrized SUSY graph and the moduli space of the metric SUSY graphs. I will outline its geometric and topological properties\, followed by a discussion on the connection with the classical case.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/3-18-2022-member-seminar/
LOCATION:Virtual
CATEGORIES:Member Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220316T103000
DTEND;TZID=America/New_York:20220316T120000
DTSTAMP:20240301T065907Z
CREATED:20240214T104642Z
LAST-MODIFIED:20240301T065907Z
UID:10002679-1647426600-1647432000@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Summing Over Bordisms In 2d TQFT
DESCRIPTION:Abstract: Some recent work in the quantum gravity literature has considered what happens when the amplitudes of a TQFT are summed over the bordisms between fixed in-going and out-going boundaries. We will comment on these constructions. The total amplitude\, that takes into account all in-going and out-going boundaries can be presented in a curious factorized form. This talk reports on work done with Anindya Banerjee and is based on the paper on the e-print arXiv  2201.00903.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/3-16-2022-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/jpeg:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-QMMP-03.16.2022-1544x2048-1.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220315T093000
DTEND;TZID=America/New_York:20220315T103000
DTSTAMP:20240304T082952Z
CREATED:20230825T075742Z
LAST-MODIFIED:20240304T082952Z
UID:10001292-1647336600-1647340200@live-hu-cmsa-222.pantheonsite.io
SUMMARY:2-categorical 3d mirror symmetry
DESCRIPTION:Abstract: It is by now well-known that mirror symmetry may be expressed as an equivalence between categories associated to dual Kahler manifolds. Following a proposal of Teleman\, we inaugurate a program to understand 3d mirror symmetry as an equivalence between 2-categories associated to dual holomorphic symplectic stacks. We consider here the abelian case\, where our theorem expresses the 2-category of spherical functors as a 2-category of coherent sheaves of categories. Applications include categorifications of hypertoric category O and of many related constructions in representation theory. This is joint work with Justin Hilburn and Aaron Mazel-Gee.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/2-categorical-3d-mirror-symmetry/
LOCATION:Virtual
CATEGORIES:Algebraic Geometry in String Theory Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220310T200000
DTEND;TZID=America/New_York:20220310T213000
DTSTAMP:20240813T163724Z
CREATED:20240214T104900Z
LAST-MODIFIED:20240813T163724Z
UID:10002680-1646942400-1646947800@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Resonant side-jump thermal Hall effect of phonons coupled to dynamical defects
DESCRIPTION:Abstract: We present computations of the thermal Hall coefficient of phonons scattering off defects with multiple energy levels. Using a microscopic formulation based on the Kubo formula\, we find that the leading contribution perturbative in the phonon-defect coupling is of the ‘side-jump’ type\, which is proportional to the phonon lifetime. This contribution is at resonance when the phonon energy equals a defect level spacing. Our results are obtained for different defect models\, and include models of an impurity quantum spin in the presence of quasi-static magnetic order with an isotropic Zeeman coupling to the applied field. \nThis work is based on arxiv: 2201.11681
URL:https://live-hu-cmsa-222.pantheonsite.io/event/3-10-2022-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/jpeg:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-QMMP-03.10.2022-1544x2048-1-1.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220309T103000
DTEND;TZID=America/New_York:20220309T120000
DTSTAMP:20240301T070302Z
CREATED:20240214T105142Z
LAST-MODIFIED:20240301T070302Z
UID:10002682-1646821800-1646827200@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Anomalies\, topological insulators and Kaehler-Dirac fermions
DESCRIPTION:Abstract: Motivated by a puzzle arising from recent work on staggered lattice fermions we introduce Kaehler-Dirac fermions and describe their connection both to Dirac fermions and staggered fermions. We show that they suffer from a gravitational anomaly that breaks a chiral U(1) symmetry specific to Kaehler-Dirac fermions down to Z_4 in any even dimension. In odd dimensions we show that the effective theory that results from integrating out massive Kaehler-Dirac fermions is a topological gravity theory. Such theories generalize Witten’s construction of (2+1) gravity as a Chern Simons theory. In the presence of a domain wall massless modes appear on the wall which can be consistently coupled to gravity due to anomaly inflow from the bulk gravitational theory. Much of this story parallels the usual discussion of topological insulators. The key difference is that the twisted chiral symmetry and anomaly structure of Kaehler-Dirac theories survives intact under discretization and governs the behavior of the lattice models. $Z_4$ invariant four fermion interactions can be used to gap out states in such theories without breaking symmetries and in flat space yields the known constraints on the number of Majorana fermions needed symmetric mass generation namely eight and sixteen Majorana spinors in two and four dimensions.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/3-9-2022-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/jpeg:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-QMMP-03.09.2022-1544x2048-1.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220307T100000
DTEND;TZID=America/New_York:20220307T113000
DTSTAMP:20240301T073931Z
CREATED:20230730T175629Z
LAST-MODIFIED:20240301T073931Z
UID:10001144-1646647200-1646652600@live-hu-cmsa-222.pantheonsite.io
SUMMARY:4d strings at strong coupling
DESCRIPTION:Speakers: Fernando Marchesano (UAM-CSIC\, Madrid)  and Max Wiesner (Harvard CMSA)\n\n\n\nTitle: 4d strings at strong coupling\n\n\nAs usual\, the format will be 45 min talk + 30 min discussion\, to encourage participation from the audience.\nLooking forward to seeing you there!
URL:https://live-hu-cmsa-222.pantheonsite.io/event/3-7-2022-swampland-seminar/
LOCATION:Virtual
CATEGORIES:Swampland Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220303T093000
DTEND;TZID=America/New_York:20220303T110000
DTSTAMP:20240813T163614Z
CREATED:20240214T105412Z
LAST-MODIFIED:20240813T163614Z
UID:10002684-1646299800-1646305200@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Callan Rubakov Effect and Higher Charge Monopoles
DESCRIPTION:Abstract: In this talk we will discuss the interaction between magnetic monopoles and massless fermions. In the 1980’s Callan and Rubakov showed that in the simplest example and that fermion-monopole interactions catalyze proton decay in GUT completions of the standard model. Here we will explain how fermions in general representations interact with general spherically symmetric monopoles and classify the types of symmetries that are broken: global symmetries with ABJ-type anomalies.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/3-3-2022-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/jpeg:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-QMMP-03.03.2022-1544x2048-1.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220302T140000
DTEND;TZID=America/New_York:20220302T150000
DTSTAMP:20240517T193649Z
CREATED:20230808T182233Z
LAST-MODIFIED:20240517T193649Z
UID:10001206-1646229600-1646233200@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Scaling Laws and Their Implications for Coding AI
DESCRIPTION:Speaker: Jared Kaplan\, Johns Hopkins Dept. of Physics & Astronomy \nTitle: Scaling Laws and Their Implications for Coding AI \nAbstract:  Scaling laws and associated downstream trends can be used as an organizing principle when thinking about current and future ML progress.  I will briefly review scaling laws for generative models in a number of domains\, emphasizing language modeling.  Then I will discuss scaling results for transfer from natural language to code\, and results on python programming performance from “codex” and other models.  If there’s time I’ll discuss prospects for the future — limitations from dataset sizes\, and prospects for RL and other techniques.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/3-2-2022-new-technologies-in-mathematics-seminar/
LOCATION:Virtual
CATEGORIES:New Technologies in Mathematics Seminar
ATTACH;FMTTYPE=image/jpeg:https://live-hu-cmsa-222.pantheonsite.io/media/03.2.2022-1553x2048-1.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220302T093000
DTEND;TZID=America/New_York:20220302T103000
DTSTAMP:20240222T171906Z
CREATED:20240214T040557Z
LAST-MODIFIED:20240222T171906Z
UID:10002521-1646213400-1646217000@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Dimers and webs
DESCRIPTION:Speaker: Richard Kenyon (Yale) \nTitle: Dimers and webs \nAbstract: We consider SL_n-local systems on graphs on surfaces and show how the associated Kasteleyn matrix can be used to compute probabilities of various topological events involving the overlay of n independent dimer covers (or “n-webs”). \nThis is joint work with Dan Douglas and Haolin Shi.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/dimers-and-webs/
LOCATION:Virtual
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/02CMSA-Colloquium-03.02.2022.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220301T093000
DTEND;TZID=America/New_York:20220301T103000
DTSTAMP:20240304T083139Z
CREATED:20230825T075625Z
LAST-MODIFIED:20240304T083139Z
UID:10001291-1646127000-1646130600@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Virtual localization for Artin stacks
DESCRIPTION:Abstract: This is a report about work in progress with: Adeel Khan\, Aloysha Latyntsev\, Hyeonjun Park and Charanya Ravi. We will describe a virtual Atiyah-Bott formula for Artin stacks.  In the Deligne-Mumford case our methods allow us to remove the global resolution hypothesis for the virtual normal bundle.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/virtual-localization-for-artin-stacks/
LOCATION:Virtual
CATEGORIES:Algebraic Geometry in String Theory Seminar
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-Algebraic-Geometry-in-String-Theory-02.22.2022-1.png
END:VEVENT
END:VCALENDAR