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BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211012T130000
DTEND;TZID=America/New_York:20211012T140000
DTSTAMP:20260510T115133
CREATED:20240214T053342Z
LAST-MODIFIED:20240304T063443Z
UID:10002540-1634043600-1634047200@cmsa.fas.harvard.edu
SUMMARY:Derived projectivizations of two-term complexes
DESCRIPTION:Abstract: For a given two-term complex of vector bundles on a derived scheme (or stack)\, there are three natural ways to define its “derived projectivizations”: (i) as the derived base-change of the classical projectivization of Grothendieck; (ii) as the derived moduli parametrizing one-dimensional locally free quotients; (iii) as the GIT quotient of the total space by $\mathbb{G}_m$-action. In this talk\, we first show that these three definitions are equivalent. Second\, we prove a structural theorem about the derived categories of derived projectivizations and study the corresponding mutation theory. Third\, we apply these results to various moduli situations\, including the moduli of certain stable pairs on curves and the Hecke correspondences of one-point modification of moduli of stable sheaves on surfaces. If time allowed\, we could also discuss the generalizations of these results to the derived Quot schemes of locally free quotients.
URL:https://cmsa.fas.harvard.edu/event/derived-projectivizations-of-two-term-complexes/
LOCATION:MA
CATEGORIES:Algebraic Geometry in String Theory Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211012T090000
DTEND;TZID=America/New_York:20211012T100000
DTSTAMP:20260510T115133
CREATED:20240213T114547Z
LAST-MODIFIED:20240304T100222Z
UID:10002513-1634029200-1634032800@cmsa.fas.harvard.edu
SUMMARY:10/12/2021 Combinatorics\, Physics and Probability Seminar
DESCRIPTION:Title: On counting algebraically defined graphs \nAbstract: For many classes of graphs that arise naturally in discrete geometry (for example intersection graphs of segments or disks in the plane)\, the edges of these graphs can be defined algebraically using the signs of a finite list of fixed polynomials. We investigate the number of n-vertex graphs in such an algebraically defined class of graphs. Warren’s theorem (a variant of a theorem of Milnor and Thom) implies upper bounds for the number of n-vertex graphs in such graph classes\, but all the previously known lower bounds were obtained from ad hoc constructions for very specific classes. We prove a general theorem giving a lower bound for this number (under some reasonable assumptions on the fixed list of polynomials)\, and this lower bound essentially matches the upper bound from Warren’s theorem.
URL:https://cmsa.fas.harvard.edu/event/10-12-2021-combinatorics-physics-and-probability-seminar/
LOCATION:MA
CATEGORIES:Combinatorics Physics and Probability
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211008T093000
DTEND;TZID=America/New_York:20211008T103000
DTSTAMP:20260510T115133
CREATED:20240214T074201Z
LAST-MODIFIED:20240301T111834Z
UID:10002568-1633685400-1633689000@cmsa.fas.harvard.edu
SUMMARY:Knowledge Graph Embeddings and Inference
DESCRIPTION:Member Seminar \nSpeaker: Michael Douglas \nTitle: Knowledge Graph Embeddings and Inference \nAbstract: A knowledge graph (KG) is a data structure which represents entities and relations as the vertices and edges of a directed graph. Two examples are Wikidata for general knowledge and SemMedDB for biomedical data.\nA popular KG representation method is graph embedding\, which facilitates question answering\, inferring missing edges\, and logical reasoning tasks. In this talk we introduce the topic and explain relevant mathematical results on graph embedding. We then analyze KG inference into several mechanisms: motif learning\, network learning\, and unstructured statistical inference\, and describe experiments to measure the contributions of each mechanism. \nJoint work with M. Simkin\, O. Ben-Eliezer\, T. Wu\, S. P. Chin\, T. V. Dang and A. Wood.
URL:https://cmsa.fas.harvard.edu/event/10-8-2021-member-seminar/
LOCATION:MA
CATEGORIES:Member Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211008T093000
DTEND;TZID=America/New_York:20211008T103000
DTSTAMP:20260510T115133
CREATED:20240213T110012Z
LAST-MODIFIED:20240304T101810Z
UID:10002469-1633685400-1633689000@cmsa.fas.harvard.edu
SUMMARY:Causality Comparison and Postive Mass
DESCRIPTION:Speaker: Xiaoning Wu\, Chinese Academy of Sciences \nTitle: Causality Comparison and Postive Mass \nAbstract: Penrose et al. investigated the physical incoherence of the space-time with negative mass via the bending of light. Precise estimates of the time-delay of null geodesics were needed and played a pivotal role in their proof. In this paper\, we construct an intermediate diagonal metric and reduce this problem to a causality comparison in the compactified space-time regarding time-like connectedness near conformal infinities. This different approach allows us to avoid encountering the difficulties and subtle issues that Penrose et al. met. It provides a new\, substantially simple\, and physically natural non-partial differential equation viewpoint to understand the positive mass theorem. This elementary argument modestly applies to asymptotically flat solutions that are vacuum and stationary near infinity
URL:https://cmsa.fas.harvard.edu/event/10-8-2021-general-relativity-seminar/
LOCATION:MA
CATEGORIES:General Relativity Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211007T203000
DTEND;TZID=America/New_York:20211007T220000
DTSTAMP:20260510T115133
CREATED:20240301T093101Z
LAST-MODIFIED:20240301T093101Z
UID:10002891-1633638600-1633644000@cmsa.fas.harvard.edu
SUMMARY:UV/IR and Effective Field Theory
DESCRIPTION:Speaker: Nima Arkani-Hamed (IAS Princeton) \nTitle: UV/IR and Effective Field Theory
URL:https://cmsa.fas.harvard.edu/event/10-7-2021-quantum-matter-in-mathematics-and-physics-2/
LOCATION:MA
CATEGORIES:Quantum Matter
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211007T184100
DTEND;TZID=America/New_York:20211007T184100
DTSTAMP:20260510T115133
CREATED:20240214T083403Z
LAST-MODIFIED:20240214T083403Z
UID:10002590-1633632060-1633632060@cmsa.fas.harvard.edu
SUMMARY:10/7/2021 Interdisciplinary Science Seminar
DESCRIPTION:Title: SiRNA Targeting TCRb: A Proposed Therapy for the Treatment of Autoimmunity \nAbstract: As of 2018\, the United States National Institutes of Health estimate that over half a billion people worldwide are affected by autoimmune disorders. Though these conditions are prevalent\, treatment options remain relatively poor\, relying primarily on various forms of immunosuppression which carry potentially severe side effects and often lose effectiveness over time. Given this\, new forms of therapy are needed. To this end\, we have developed methods for the creation of small-interfering RNA (siRNA) for hypervariable regions of the T-cell receptor β-chain gene (TCRb) as a highly targeted\, novel means of therapy for the treatment of autoimmune disorders. \nThis talk will review the general mechanism by which autoimmune diseases occur and discuss the pros and cons of conventional pharmaceutical therapies as they pertain to autoimmune disease treatment. I will then examine the rational and design methodology for the proposed siRNA therapy and how it contrasts with contemporary methods for the treatment of these conditions. Additionally\, the talk will compare the efficacy of multiple design strategies for such molecules by comparison over several metrics and discuss how this will be guiding future research.
URL:https://cmsa.fas.harvard.edu/event/10-7-2021-interdisciplinary-science-seminar/
LOCATION:MA
CATEGORIES:Interdisciplinary Science Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211007T130000
DTEND;TZID=America/New_York:20211007T140000
DTSTAMP:20260510T115133
CREATED:20240214T053935Z
LAST-MODIFIED:20240304T063527Z
UID:10002541-1633611600-1633615200@cmsa.fas.harvard.edu
SUMMARY:A mirror theorem for GLSMs
DESCRIPTION:Abstract: A gauged linear sigma model (GLSM) consists roughly of a complex vector space V\, a group G acting on V\, a character \theta of G\, and a G-invariant function w on V.  This data defines a GIT quotient Y = [V //_\theta G] and a function on that quotient.  GLSMs arise naturally in a number of contexts\, for instance as the mirrors to Fano manifolds and as examples of noncommutative crepant resolutions. GLSMs provide a broad setting in which it is possible to define an enumerative curve counting theory\, simultaneously generalizing FJRW theory and the Gromov-Witten theory of hypersurfaces. Despite a significant effort to rigorously define the enumerative invariants of a GLSM\, very few computations of these invariants have been carried out.  In this talk I will describe a new method for computing generating functions of GLSM invariants.  I will explain how these generating functions arise as derivatives of generating functions of Gromov-Witten invariants of Y.
URL:https://cmsa.fas.harvard.edu/event/a-mirror-theorem-for-glsms/
LOCATION:MA
CATEGORIES:Algebraic Geometry in String Theory Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211007T115400
DTEND;TZID=America/New_York:20211007T135400
DTSTAMP:20260510T115133
CREATED:20240214T090253Z
LAST-MODIFIED:20240301T092837Z
UID:10002604-1633607640-1633614840@cmsa.fas.harvard.edu
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://cmsa.fas.harvard.edu/event/10-7-2021-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211006T150000
DTEND;TZID=America/New_York:20211006T160000
DTSTAMP:20260510T115133
CREATED:20240214T092921Z
LAST-MODIFIED:20240517T200621Z
UID:10002630-1633532400-1633536000@cmsa.fas.harvard.edu
SUMMARY:New results in Supergravity via ML Technology
DESCRIPTION:Speaker: Thomas Fischbacher\, Google \nTitle: New results in Supergravity via ML Technology \nAbstract: The infrastructure built to power the Machine Learning revolution has many other uses beyond Deep Learning. Starting from a general architecture-level overview over the lower levels of Google’s TensorFlow machine learning library\, we review how this has recently helped us to find all the stable vacua of SO(8) Supergravity in 3+1 dimensions\, has allowed major progress on other related questions about M theory\, and briefly discuss other applications in field theory and beyond.
URL:https://cmsa.fas.harvard.edu/event/10-6-2021-new-technologies-in-mathematics-seminar/
LOCATION:MA
CATEGORIES:New Technologies in Mathematics Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211006T114900
DTEND;TZID=America/New_York:20211006T134900
DTSTAMP:20260510T115133
CREATED:20240214T090718Z
LAST-MODIFIED:20240301T093241Z
UID:10002606-1633520940-1633528140@cmsa.fas.harvard.edu
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://cmsa.fas.harvard.edu/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:20260510T115133
CREATED:20240214T044013Z
LAST-MODIFIED:20240501T205719Z
UID:10002532-1633512600-1633516200@cmsa.fas.harvard.edu
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://cmsa.fas.harvard.edu/event/strings-knots-and-quivers/
LOCATION:Virtual
CATEGORIES:Colloquium
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211005T090000
DTEND;TZID=America/New_York:20211005T100000
DTSTAMP:20260510T115133
CREATED:20240213T113617Z
LAST-MODIFIED:20240304T085033Z
UID:10002508-1633424400-1633428000@cmsa.fas.harvard.edu
SUMMARY:10/5/2021 Combinatorics\, Physics and Probability Seminar
DESCRIPTION:Title: Geodesic Geometry on Graphs \nAbstract: In a graph G = (V\, E) we consider a system of paths S so that for every two vertices u\,v in V there is a unique uv path in S connecting them. The path system is said to be consistent if it is closed under taking subpaths\, i.e. if P is a path in S then any subpath of P is also in S. Every positive weight function w: E–>R^+ gives rise to a consistent path system in G by taking the paths in S to be geodesics w.r.t. w. In this case\, we say w induces S. We say a graph G is metrizable if every consistent path system in G is induced by some such w. \nWe’ll discuss the concept of graph metrizability\, and\, in particular\, we’ll see that while metrizability is a rare property\, there exists infinitely many 2-connected metrizable graphs. \nJoint work with Nati Linial.
URL:https://cmsa.fas.harvard.edu/event/10-5-2021-combinatorics-physics-and-probability-seminar/
LOCATION:MA
CATEGORIES:Combinatorics Physics and Probability
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211005T083000
DTEND;TZID=America/New_York:20211005T093000
DTSTAMP:20260510T115133
CREATED:20240213T111744Z
LAST-MODIFIED:20240304T104852Z
UID:10002487-1633422600-1633426200@cmsa.fas.harvard.edu
SUMMARY:Angular momentum in general relativity
DESCRIPTION:Abstract: The definition of angular momentum in general relativity has been a subtle issue since the 1960′\, due to the discovery of “supertranslation ambiguity”: the angular momentums recorded by two distant observers of the same system may not be the same. In this talk\, I shall show how the mathematical theory of optimal isometric embedding and quasilocal angular momentum identifies a correction term\, and leads to a new definition of angular momentum that is free of any supertranslation ambiguity. This is based on joint work with Po-Ning Chen\, Jordan Keller\, Ye-Kai Wang\, and Shing-Tung Yau.
URL:https://cmsa.fas.harvard.edu/event/10-5-2021-joint-harvard-cuhk-ymsc-differential-geometry-seminar/
LOCATION:MA
CATEGORIES:Joint Harvard-CUHK-YMSC Differential Geometry
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211004T110000
DTEND;TZID=America/New_York:20211004T123000
DTSTAMP:20260510T115133
CREATED:20240212T110410Z
LAST-MODIFIED:20250409T192600Z
UID:10002032-1633345200-1633350600@cmsa.fas.harvard.edu
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://cmsa.fas.harvard.edu/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:20211004T025100
DTEND;TZID=America/New_York:20211005T025100
DTSTAMP:20260510T115133
CREATED:20230705T081940Z
LAST-MODIFIED:20250328T200226Z
UID:10000071-1633315860-1633402260@cmsa.fas.harvard.edu
SUMMARY:Math Science Lectures in Honor of Raoul Bott
DESCRIPTION:On October 4th and October 5th\, 2021\, Harvard CMSA will host its annual Math Science Lectures in Honor of Raoul Bott. This year’s speaker will be Michael Freedman (Microsoft). The lectures will take place from 11:00am – 12:15pm (ET) 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://cmsa.fas.harvard.edu/event/math-science-lectures-in-honor-of-raoul-bott/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Event,Public Lecture,Special Lectures
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211001T093000
DTEND;TZID=America/New_York:20211001T103000
DTSTAMP:20260510T115133
CREATED:20240304T101543Z
LAST-MODIFIED:20240304T101543Z
UID:10002898-1633080600-1633084200@cmsa.fas.harvard.edu
SUMMARY:Static vacuum extensions of Bartnik boundary data near flat domains
DESCRIPTION:Abstract: The study of static vacuum Riemannian metrics arises naturally in differential geometry and general relativity. It plays an important role in scalar curvature deformation\, as well as in constructing Einstein spacetimes.  Existence of static vacuum Riemannian metrics with prescribed Bartnik data is one of the most fundamental problems in Riemannian geometry related to general relativity. It is also a very interesting problem on the global solvability of a natural geometric boundary value problem. In this talk I will first discuss some basic properties of the nonlinear and linearized static vacuum equations and the geometric boundary conditions. Then I will present some recent progress towards the existence problem of static vacuum metrics based on a joint work with Lan-Hsuan Huang.
URL:https://cmsa.fas.harvard.edu/event/10-1-2021-general-relativity-seminar/
LOCATION:MA
CATEGORIES:General Relativity Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211001T093000
DTEND;TZID=America/New_York:20211001T103000
DTSTAMP:20260510T115133
CREATED:20240214T074545Z
LAST-MODIFIED:20240301T111944Z
UID:10002569-1633080600-1633084200@cmsa.fas.harvard.edu
SUMMARY:Instability of naked singularities in general relativity
DESCRIPTION:Member Seminar \nSpeaker: Jue Liu \nTitle: Instability of naked singularities in general relativity \nAbstract: One of the fundamental problems in mathematical relativity is the weak cosmic censorship conjecture\, proposed by Penrose\, which roughly states that for generic physical spacetime\, the singularities (if existed) must be hidden behind the black holes. Unfortunately\, the singularities visible to faraway observers\, which are called by naked singularities\, indeed exist. The first example constructed by Christodoulou in 1994 is a family of self-similar spherically symmetric spacetime\, in which the naked singularity forms due to a self-gravitating scalar field. Therefore the suitable censorship conjecture should be reduced to prove the instability of the naked singularities. In 1999 Christodoulou succeeded to prove the weak cosmic censorship conjecture in spherically symmetric cases\, and recently the co-author and I found that the corresponding results have a big probability to be extended to spacetime without symmetries. In this talk I will discuss how to prove the instability of naked singularities using the energy method\, and it is this wild method that helps us to extend some results to the asymmetric cases.
URL:https://cmsa.fas.harvard.edu/event/10-1-2021-member-seminar/
LOCATION:MA
CATEGORIES:Member Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20210930T130000
DTEND;TZID=America/New_York:20210930T143000
DTSTAMP:20260510T115133
CREATED:20230824T171544Z
LAST-MODIFIED:20240304T084438Z
UID:10001305-1633006800-1633012200@cmsa.fas.harvard.edu
SUMMARY:Cytoskeletal Energetics and Energy Metabolism
DESCRIPTION:Abstract: Life is a nonequilibrium phenomenon. Metabolism provides a continuous flux of energy that dictates the form and function of many subcellular structures. These subcellular structures are active materials\, composed of molecules which use chemical energy to perform mechanical work and locally violate detailed balance. One of the most dramatic examples of such a self-organizing structure is the spindle\, the cytoskeletal based assembly which segregates chromosomes during cell division. Despite its central role\, very little is known about the nonequilibrium thermodynamics of active subcellular matter\, such as the spindle. In this talk\, I will describe ongoing work from my lab aimed at understanding the flows of energy which drive the nonequilibrium behaviors of the cytoskeleton in vitro and in vivo.
URL:https://cmsa.fas.harvard.edu/event/cytoskeletal-energetics-and-energy-metabolism/
LOCATION:MA
CATEGORIES:Active Matter Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20210929T171500
DTEND;TZID=America/New_York:20210929T181500
DTSTAMP:20260510T115133
CREATED:20240214T055645Z
LAST-MODIFIED:20240304T065421Z
UID:10002546-1632935700-1632939300@cmsa.fas.harvard.edu
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://cmsa.fas.harvard.edu/event/langlands-duality-for-3-manifolds/
LOCATION:Virtual
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Colloquium-09.29.21.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20210929T150000
DTEND;TZID=America/New_York:20210929T160000
DTSTAMP:20260510T115133
CREATED:20240214T092650Z
LAST-MODIFIED:20240517T200354Z
UID:10002626-1632927600-1632931200@cmsa.fas.harvard.edu
SUMMARY:Constructions in combinatorics via neural networks
DESCRIPTION:Speaker: Adam Wagner\, Tel Aviv University \nTitle: Constructions in combinatorics via neural networks \nAbstract: Recently\, significant progress has been made in the area of machine learning algorithms\, and they have quickly become some of the most exciting tools in a scientist’s toolbox. In particular\, recent advances in the field of reinforcement learning have led computers to reach superhuman level play in Atari games and Go\, purely through self-play. In this talk I will give a very basic introduction to neural networks and reinforcement learning algorithms. I will also indicate how these methods can be adapted to the ““game” of trying to find a counterexample to a mathematical conjecture\, and show some examples where this approach was successful.
URL:https://cmsa.fas.harvard.edu/event/9-29-2021-new-technologies-in-mathematics-seminar/
LOCATION:MA
CATEGORIES:New Technologies in Mathematics Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20210929T114800
DTEND;TZID=America/New_York:20210929T134800
DTSTAMP:20260510T115133
CREATED:20240214T090955Z
LAST-MODIFIED:20240301T093415Z
UID:10002610-1632916080-1632923280@cmsa.fas.harvard.edu
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://cmsa.fas.harvard.edu/event/9-29-2021-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20210928T130000
DTEND;TZID=America/New_York:20210928T140000
DTSTAMP:20260510T115133
CREATED:20240214T054256Z
LAST-MODIFIED:20240304T064006Z
UID:10002542-1632834000-1632837600@cmsa.fas.harvard.edu
SUMMARY:The Mirror Clemens-Schmid Sequence
DESCRIPTION:Abstract: I will present a four-term exact sequence relating the cohomology of a fibration to the cohomology of an open set obtained by removing the preimage of a general linear section of the base. This exact sequence respects three filtrations\, the Hodge\, weight\, and perverse Leray filtrations\, so that it is an exact sequence of mixed Hodge structures on the graded pieces of the perverse Leray filtration. I claim that this sequence should be thought of as a mirror to the Clemens-Schmid sequence describing the structure of a degeneration and formulate a “mirror P=W” conjecture relating the filtrations on each side. Finally\, I will present evidence for this conjecture coming from the K3 surface setting. This is joint work with Charles F. Doran.
URL:https://cmsa.fas.harvard.edu/event/the-mirror-clemens-schmid-sequence/
LOCATION:MA
CATEGORIES:Algebraic Geometry in String Theory Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20210928T130000
DTEND;TZID=America/New_York:20210928T130000
DTSTAMP:20260510T115133
CREATED:20240214T045955Z
LAST-MODIFIED:20240304T060348Z
UID:10002535-1632834000-1632834000@cmsa.fas.harvard.edu
SUMMARY:9/28/2021 Combinatorics\, Physics and Probability Seminar
DESCRIPTION:Title: The hypersimplex and the m=2 amplituhedron \nAbstract: I’ll discuss a curious correspondence between the m=2 amplituhedron\, a 2k-dimensional subset of Gr(k\, k+2)\, and the hypersimplex\, an (n-1)-dimensional polytope in R^n. The amplituhedron and hypersimplex are both images of the totally nonnegative Grassmannian under some map (the amplituhedron map and the moment map\, respectively)\, but are different dimensions and live in very different ambient spaces. I’ll talk about joint work with Matteo Parisi and Lauren Williams in which we give a bijection between decompositions of the amplituhedron and decompositions of the hypersimplex (originally conjectured by Lukowski–Parisi–Williams). Along the way\, we prove the sign-flip description of the m=2 amplituhedron conjectured by Arkani-Hamed–Thomas–Trnka and give a new decomposition of the m=2 amplituhedron into Eulerian-number-many chambers (inspired by an analogous hypersimplex decomposition).
URL:https://cmsa.fas.harvard.edu/event/9-28-2021-combinatorics-physics-and-probability-seminar/
LOCATION:MA
CATEGORIES:Combinatorics Physics and Probability
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20210927T130000
DTEND;TZID=America/New_York:20210927T140000
DTSTAMP:20260510T115134
CREATED:20240214T093736Z
LAST-MODIFIED:20240301T083146Z
UID:10002640-1632747600-1632751200@cmsa.fas.harvard.edu
SUMMARY:Convexity of Charged Operators in CFTs and the Weak Gravity Conjecture
DESCRIPTION:Abstract: In this talk I will introduce a particular formulation of the Weak Gravity Conjecture in AdS space in terms of the self-binding energy of a particle. The holographic CFT dual of this formulation corresponds to a certain convex-like structure for operators charged under continuous global symmetries. Motivated by this\, we propose a conjecture that this convexity is a general property of all CFTs\, not just those with weakly-curved gravitational duals. It is possible to test this in simple CFTs\, the conjecture passes all the tests performed so far.
URL:https://cmsa.fas.harvard.edu/event/9-27-2021-swampland-seminar/
LOCATION:MA
CATEGORIES:Swampland Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20210924T093000
DTEND;TZID=America/New_York:20210924T103000
DTSTAMP:20260510T115134
CREATED:20240214T075925Z
LAST-MODIFIED:20240301T112341Z
UID:10002575-1632475800-1632479400@cmsa.fas.harvard.edu
SUMMARY:Stability and convergence issues in mathematical cosmology
DESCRIPTION:Member Seminar \nSpeaker: Puskar Mondal \nTitle: Stability and convergence issues in mathematical cosmology \nAbstract: The standard model of cosmology is built on the fact that while viewed on a sufficiently coarse-grained scale the portion of our universe that is accessible to observation appears to be spatially homogeneous and isotropic. Therefore this observed `homogeneity and isotropy’ of our universe is not known to be dynamically derived. In this talk\, I will present an interesting dynamical mechanism within the framework of the Einstein flow (including physically reasonable matter sources) which suggests that many closed manifolds that do not support homogeneous and isotropic metrics at all will nevertheless evolve to be asymptotically compatible with the observed approximate homogeneity and isotropy of the physical universe. This asymptotic spacetime is naturally isometric to the standard FLRW models of cosmology. In order to conclude to what extent the asymptotic state is physically realized\, one needs to study its stability properties. Therefore\, I will briefly discuss the stability issue and its consequences (e.g.\, structure formation\, etc).
URL:https://cmsa.fas.harvard.edu/event/9-24-2021-member-seminar/
LOCATION:MA
CATEGORIES:Member Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20210924T093000
DTEND;TZID=America/New_York:20210924T103000
DTSTAMP:20260510T115134
CREATED:20240213T113915Z
LAST-MODIFIED:20240304T100711Z
UID:10002510-1632475800-1632479400@cmsa.fas.harvard.edu
SUMMARY:9/24/2021 General Relativity Seminar
DESCRIPTION:Title: On the Observable Shape of Black Hole Photon Rings \nAbstract: The photon ring is a narrow ring-shaped feature\, predicted by General Relativity but not yet observed\, that appears on images of sources near a black hole. It is caused by extreme bending of light within a few Schwarzschild radii of the event horizon and provides a direct probe of the unstable bound photon orbits of the Kerr geometry. I will argue that the precise shape of the observable photon ring is remarkably insensitive to the astronomical source profile and can therefore be used as a stringent test of strong-field General Relativity. In practice\, near-term interferometric observations may be limited to the visibility amplitude alone\, which contains incomplete shape information: for convex curves\, the amplitude only encodes the set of projected diameters (or “widths”) of the shape. I will describe the freedom in reconstructing a convex curve from its widths\, giving insight into the photon ring shape information probed by technically plausible future astronomical measurements.
URL:https://cmsa.fas.harvard.edu/event/9-24-2021-general-relativity-seminar/
LOCATION:MA
CATEGORIES:General Relativity Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20210923T184000
DTEND;TZID=America/New_York:20210923T204000
DTSTAMP:20260510T115134
CREATED:20240214T083814Z
LAST-MODIFIED:20240301T104847Z
UID:10002591-1632422400-1632429600@cmsa.fas.harvard.edu
SUMMARY:9/23/2021 Interdisciplinary Science Seminar
DESCRIPTION:Title: 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://cmsa.fas.harvard.edu/event/9-23-2021-interdisciplinary-science-seminar/
LOCATION:MA
CATEGORIES:Interdisciplinary Science Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20210923T130000
DTEND;TZID=America/New_York:20210923T143000
DTSTAMP:20260510T115134
CREATED:20240213T112248Z
LAST-MODIFIED:20240304T084241Z
UID:10002493-1632402000-1632407400@cmsa.fas.harvard.edu
SUMMARY:The many phases of a cell
DESCRIPTION:Abstract: I will begin by introducing an emerging paradigm of cellular organization – the dynamic compartmentalization of biochemical pathways and molecules by phase separation into distinct and multi-phase condensates. Motivated by this\, I will discuss two largely orthogonal problems\, united by the theme of phase separation in multi-component and chemically active fluid mixtures. \n1. I will propose a theoretical model based on Random-Matrix Theory\, validated by phase-field simulations\, to characterizes the rich emergent dynamics\, compositions\, and steady-state properties that underlie multi-phase coexistence in fluid mixtures with many randomly interacting components. \n2. Motivated by puzzles in gene-regulation and nuclear organization\, I will propose a role for how liquid-like nuclear condensates can be organized and regulated by the active process of RNA synthesis (transcription) and RNA-protein coacervation. Here\, I will describe theory and simulations based on a Landau formalism and recent experimental results from collaborators.
URL:https://cmsa.fas.harvard.edu/event/the-many-phases-of-a-cell/
LOCATION:MA
CATEGORIES:Active Matter Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20210923T114700
DTEND;TZID=America/New_York:20210923T134700
DTSTAMP:20260510T115134
CREATED:20240214T091227Z
LAST-MODIFIED:20240301T093540Z
UID:10002612-1632397620-1632404820@cmsa.fas.harvard.edu
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://cmsa.fas.harvard.edu/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:20260510T115134
CREATED:20240212T111100Z
LAST-MODIFIED:20240222T072551Z
UID:10002042-1632387600-1632391200@cmsa.fas.harvard.edu
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://cmsa.fas.harvard.edu/event/interdisciplinary-science-seminar/
LOCATION:Virtual
CATEGORIES:Interdisciplinary Science Seminar
END:VEVENT
END:VCALENDAR