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X-WR-CALDESC:Events for CMSA
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DTSTART;TZID=America/New_York:20230503T153000
DTEND;TZID=America/New_York:20230503T163000
DTSTAMP:20240111T083748Z
CREATED:20230808T175916Z
LAST-MODIFIED:20240111T083748Z
UID:10001198-1683127800-1683131400@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Random Neural Networks
DESCRIPTION:Probability Seminar \nSpeaker: Boris Hanin (Princeton)\n\nTitle: Random Neural Networks \nAbstract: Fully connected neural networks are described two by structural parameters: a depth L and a width N. In this talk\, I will present results and open questions about the asymptotic analysis of such networks with random weights and biases in the regime where N (and potentially L) are large. The first set of results are for deep linear networks\, which are simply products of L random matrices of size N x N. I’ll explain how the setting where the ratio L / N is fixed with both N and L large reveals a number of phenomena not present when only one of them is large. I will then state several results about non-linear networks in which this depth-to-width ratio L / N again plays a crucial role and gives an effective notion of depth for a random neural network.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/probability-5323/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Probability Seminar
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-Probability-Seminar-05.03.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230503T123000
DTEND;TZID=America/New_York:20230503T133000
DTSTAMP:20240216T085646Z
CREATED:20230817T183740Z
LAST-MODIFIED:20240216T085646Z
UID:10001284-1683117000-1683120600@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Generative Adversarial Networks (GANs): An Analytical Perspective
DESCRIPTION:Speaker: Xin Guo\, UC Berkeley \nTitle: Generative Adversarial Networks (GANs): An Analytical Perspective \nAbstract: Generative models have attracted intense interests recently. In this talk\, I will discuss one class of generative models\, Generative Adversarial Networks (GANs).  I will first provide a gentle review of the mathematical framework behind GANs. I will then proceed to discuss a few challenges in GANs training from an analytical perspective. I will finally report some recent progress for GANs training in terms of its stability and convergence analysis. \n 
URL:https://live-hu-cmsa-222.pantheonsite.io/event/collquium-5323/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-Colloquium-05.03.2023.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230502T120000
DTEND;TZID=America/New_York:20230502T130000
DTSTAMP:20240118T085308Z
CREATED:20230817T171918Z
LAST-MODIFIED:20240118T085308Z
UID:10001244-1683028800-1683032400@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Toroidal Positive Mass Theorem
DESCRIPTION:Member Seminar \nSpeaker: Aghil Alaee \nTitle: Toroidal Positive Mass Theorem \nAbstract: In this talk\, we review the positive mass conjecture in general relativity and prove a toroidal version of this conjecture in an asymptotically hyperbolic setting.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/member-seminar-5223/
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:20230427T130000
DTEND;TZID=America/New_York:20230427T140000
DTSTAMP:20240209T052245Z
CREATED:20230824T183024Z
LAST-MODIFIED:20240209T052245Z
UID:10001810-1682600400-1682604000@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Competition at the front of expanding populations
DESCRIPTION:Active Matter Seminar\n\n\nSpeaker: Mehran Kardar\, MIT \nTitle: Competition at the front of expanding populations \nAbstract: When competing species grow into new territory\, the population is dominated by descendants of successful ancestors at the expansion front. Successful ancestry depends on the reproductive advantage (fitness)\, as well as ability and opportunity to colonize new domains. (1) Based on symmetry considerations\, we present a model that  integrates both elements by coupling the classic description of one-dimensional competition (Fisher equation) to the minimal model of front shape (KPZ equation). Macroscopic manifestations of these equations on growth morphology are explored\, providing a framework to study spatial competition\, fixation\, and differentiation\, In particular\, we find that ability to expand in space may overcome reproductive advantage in colonizing new territory. (2) Variations of fitness\, as well as fixation time upon differentiation\, are shown to belong to distinct universality classes depending on limits to gain of fitness.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/am-42723/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Active Matter Seminar
ATTACH;FMTTYPE=:
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230426T153000
DTEND;TZID=America/New_York:20230426T163000
DTSTAMP:20240111T083026Z
CREATED:20230808T175545Z
LAST-MODIFIED:20240111T083026Z
UID:10001197-1682523000-1682526600@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Boundary current fluctuations for the half space ASEP
DESCRIPTION:Probability Seminar \nSpeaker: Jimmy He (MIT) \nTitle: Boundary current fluctuations for the half space ASEP \nAbstract: The half space asymmetric simple exclusion process (ASEP) is an interacting particle system on the half line\, with particles allowed to enter/exit at the boundary. I will discuss recent work on understanding fluctuations for the number of particles in the half space ASEP started with no particles\, which exhibits the Baik-Rains phase transition between GSE\, GOE\, and Gaussian fluctuations as the boundary rates vary. As part of the proof\, we find new distributional identities relating this system to two other models\, the half space Hall-Littlewood process\, and the free boundary Schur process\, which allows exact formulas to be computed.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/probability-42623/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Probability Seminar
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-Probability-Seminar-04.26.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230426T123000
DTEND;TZID=America/New_York:20230426T133000
DTSTAMP:20240122T053311Z
CREATED:20230817T183259Z
LAST-MODIFIED:20240122T053311Z
UID:10001283-1682512200-1682515800@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Boundary behavior at classical and quantum phase transitions
DESCRIPTION:Speaker: Max Metlitski (MIT) \nTitle: Boundary behavior at classical and quantum phase transitions \nAbstract: There has been a lot of recent interest in the boundary behavior of materials. This interest is driven in part by the field of topological states of quantum matter\, where exotic protected boundary states are ubiquitous. In this talk\, I’ll ask: what happens at a boundary of a system\, when the bulk goes through a phase transition. While this question was studied in the context of classical statistical mechanics in the 70s and 80s\, basic aspects of the boundary phase diagram for the simplest classical phase transitions have been missed until recently. I’ll describe progress in this field\, as well as some extensions to quantum phase transitions. \n 
URL:https://live-hu-cmsa-222.pantheonsite.io/event/collquium-42623/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-Colloquium-04.26.2023.rev2_.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230425T120000
DTEND;TZID=America/New_York:20230425T130000
DTSTAMP:20240118T071815Z
CREATED:20230817T171725Z
LAST-MODIFIED:20240118T071815Z
UID:10001243-1682424000-1682427600@live-hu-cmsa-222.pantheonsite.io
SUMMARY:On complete Calabi-Yau metrics and some related Monge-Ampere equations
DESCRIPTION:Member Seminar \nSpeaker: Freid Tong \nTitle: On complete Calabi-Yau metrics and some related Monge-Ampere equations \nAbstract: We will give a basic introduction to constructions for complete Calabi-Yau metrics. A systematic approach to construct such metrics using PDE methods was proposed in the work of Tian-Yau in the 90s and have attracted a lot of attention in recent years. I will discuss some joint work with B. Guo and T. Collins on a singular version of such a construction\, as well as some ongoing work with Prof. Yau on some related boundary value problems. \n 
URL:https://live-hu-cmsa-222.pantheonsite.io/event/member-seminar-42523/
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:20230424T133000
DTEND;TZID=America/New_York:20230424T143000
DTSTAMP:20240119T052608Z
CREATED:20230818T043218Z
LAST-MODIFIED:20240119T052608Z
UID:10001261-1682343000-1682346600@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Recent advances in scalar curvature and positive mass theorems
DESCRIPTION:General Relativity Seminar \nSpeaker: Tin Yau Tsang\, University of California Irvine \nTitle: Recent advances in scalar curvature and positive mass theorems\n\nAbstract:  First\, we have a review of classical tools for studying scalar curvature and positive mass theorem. Then we are going to discuss some advances and new perspectives on these tools which lead to a deeper understanding of geometry and initial data sets.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/gr_42423/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:General Relativity Seminar
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-GR-Seminar-04.24.23-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230420T133000
DTEND;TZID=America/New_York:20230420T143000
DTSTAMP:20240216T085423Z
CREATED:20230817T182708Z
LAST-MODIFIED:20240216T085423Z
UID:10001282-1681997400-1682001000@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Black hole collider physics
DESCRIPTION:Speaker: Julio Parra Martinez\, Caltech \nTitle: Black hole collider physics \nAbstract: Despite more than a century since the development of Einstein’s theory\, the general relativistic two-body problem remains unsolved. A precise description of its solution is now essential\, as it is necessary for understanding the strong-gravity dynamics of compact binaries observed at LIGO/VIRGO/KAGRA and in future gravitational wave observatories. In this talk\, I will describe how considering the scattering of black holes and gravitons can shed new light on this problem. I will explain how using modern ideas from collider and particle physics we can calculate scattering observables in classical gravity\, and extract the basic ingredients that describe the bound binary dynamics. Such calculations have produced state-of-art predictions for current and future gravitational wave observatories\, which open the door for further discovery as we enter this new era of precision gravitational physics.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/collquium-42023/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-Colloquium-04.20.2023.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230413T130000
DTEND;TZID=America/New_York:20230413T140000
DTSTAMP:20240216T112442Z
CREATED:20230824T182821Z
LAST-MODIFIED:20240216T112442Z
UID:10001811-1681390800-1681394400@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Control of actin cable length by decelerated growth and network geometry
DESCRIPTION:Active Matter Seminar\n\n\nSpeaker: Shane McInally\, Brandeis \nTitle: Control of actin cable length by decelerated growth and network geometry \nAbstract: The sizes of many subcellular structures are coordinated with cell size to ensure that these structures meet the functional demands of the cell. In eukaryotic cells\, these subcellular structures are often membrane-bound organelles\, whose volume is the physiologically important aspect of their size. Scaling organelle volume with cell volume can be explained by limiting pool mechanisms\, wherein a constant concentration of molecular building blocks enables subcellular structures to increase in size proportionally with cell volume. However\, limiting pool mechanisms cannot explain how the size of linear subcellular structures\, such as cytoskeletal filaments\, scale with the linear dimensions of the cell. Recently\, we discovered that the length of actin cables in budding yeast (used for intracellular transport) precisely matches the length of the cell in which they are assembled. Using mathematical modeling and quantitative imaging of actin cable growth dynamics\, we found that as the actin cables grow longer\, their extension rates slow (or decelerate)\, enabling cable length to match cell length. Importantly\, this deceleration behavior is cell-length dependent\, allowing cables in longer cells to grow faster\, and therefore reach a longer length before growth stops at the back of the cell. In addition\, we have unexpectedly found that cable length is specified by cable shape. Our imaging analysis reveals that cables progressively taper as they extend from the bud neck into the mother cell\, and further\, this tapering scales with cell length. Integrating observations made for tapering actin networks in other systems\, we have developed a novel mathematical model for cable length control that recapitulates our quantitative experimental observations. Unlike other models of size control\, this model does not require length-dependent rates of assembly or disassembly. Instead\, feedback control over the length of the cable is an emergent property due to the cross-linked and bundled architecture of the actin filaments within the cable. This work reveals a new strategy that cells use to coordinate the size of their internal parts with their linear dimensions. Similar design principles may control the size and scaling of other subcellular structures whose physiologically important dimension is their length.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/am-41323/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Active Matter Seminar
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-Active-Matter-Seminar-04.13.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230413T093000
DTEND;TZID=America/New_York:20230413T103000
DTSTAMP:20240228T081413Z
CREATED:20230818T042744Z
LAST-MODIFIED:20240228T081413Z
UID:10001260-1681378200-1681381800@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Resolving the photon ring
DESCRIPTION:General Relativity Seminar \nSpeaker: Shahar Hadar (University of Haifa) \nTitle: Resolving the photon ring \nAbstract: In the past few years\, the Event Horizon Telescope has released the first close-up interferometric images of two supermassive black holes\, M87* and SgrA*. It is believed that within these images is embedded a fine\, yet-unresolved brightness enhancement called the photon ring. The ring is a universal consequence of strong lensing by the black hole and thereby conveys information on its spacetime geometry\, potentially providing a new independent avenue for tests of general relativity in the strong-field regime. In the talk I will briefly review the theory of the photon ring and its corresponding spacetime region\, the photon shell\, which governs the universal lensing structure. I will then describe some current efforts and future prospects for resolving the ring\, which include both the construction of transformative new instruments and the development of novel analysis methods. Focusing on the latter\, I will present an upcoming proposal to use spectro-temporal autocorrelations in signals emitted from black hole environs as a probe of strong lensing effects.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/gr_41323/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:General Relativity Seminar
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-GR-Seminar-04.13.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230412T153000
DTEND;TZID=America/New_York:20230412T163000
DTSTAMP:20240228T094844Z
CREATED:20230808T174934Z
LAST-MODIFIED:20240228T094844Z
UID:10001195-1681313400-1681317000@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Large deviations of Selberg’s central limit theorem
DESCRIPTION:Probability Seminar \n\nSpeaker: Emma Bailey (CUNY) \nTitle: Large deviations of Selberg’s central limit theorem \nAbstract: Selberg’s CLT concerns the typical behaviour of the Riemann zeta function and shows that the random variable $\Re \log \zeta(1/2 + i t)$\, for a uniformly drawn $t$\, behaves as a Gaussian random variable with a particular variance.  It is natural to investigate how far into the tails this Gaussianity persists\, which is the topic of this work. There are also very close connections to similar problems in circular unitary ensemble characteristic polynomials.  It transpires that a `multiscale scheme’ can be applied to both situations to understand these questions of large deviations\, as well as certain maxima and moments. In this talk I will focus more on the techniques we apply to approach this problem and I will assume no number theoretic knowledge. This is joint work with Louis-Pierre Arguin.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/probability-41223/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Probability Seminar
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-Probability-Seminar-04.12.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230412T123000
DTEND;TZID=America/New_York:20230412T133000
DTSTAMP:20240215T103145Z
CREATED:20230817T182227Z
LAST-MODIFIED:20240215T103145Z
UID:10001281-1681302600-1681306200@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Unexpected Uses of Neural Networks: Field Theory and Metric Flows  
DESCRIPTION:Speaker: James Halverson (Northeastern University)\n \nTitle: Unexpected Uses of Neural Networks: Field Theory and Metric Flows\nAbstract:  We are now quite used to the idea that deep neural networks may be trained in a variety of ways to tackle cutting-edge problems in physics and mathematics\, sometimes leading to rigorous results. In this talk\, however\, I will argue that breakthroughs in deep learning theory are also useful for making progress\, focusing on applications to field theory and metric flows. Specifically\, I will introduce a neural network approach to field theory with a different statistical origin\, that exhibits generalized free field behavior at infinite width and interactions at finite width\, and that allows for the study of symmetries via the study of correlation functions in a different duality frame. Then\, I will review recent progress in approximating Calabi-Yau metrics as neural networks and cast that story into the language of neural tangent kernel theory\, yielding a theoretical understanding of neural network metric flows induced by gradient descent and recovering famous metric flows\, such as Perelman’s formulation of Ricci flow\, in particular limits.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/colloquium12523/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/02CMSA-Colloquium-04.12.2023.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230411T120000
DTEND;TZID=America/New_York:20230411T130000
DTSTAMP:20240118T070619Z
CREATED:20230817T171211Z
LAST-MODIFIED:20240118T070619Z
UID:10001241-1681214400-1681218000@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Spectral gap and two-point functions in spin glasses
DESCRIPTION:Member Seminar \nSpeaker: Changji Xu \nTitle: Spectral gap and two-point functions in spin glasses \nAbstract: Many have worked on spin glass models over the past 50 years\, including physicists\, mathematicians\, and computers. A question that arises is whether computers yield dependable simulation results. In this talk\, I will discuss some recent mathematical progress on spectral gap and two-point functions in spin glasses models.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/member-seminar-41123/
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:20230410T110000
DTEND;TZID=America/New_York:20230410T120000
DTSTAMP:20240215T101627Z
CREATED:20230730T190732Z
LAST-MODIFIED:20240215T101627Z
UID:10001161-1681124400-1681128000@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Swampland bounds on the abelian gauge sectors
DESCRIPTION:Swampland Seminar \nSpeaker: Seung-Joo Lee (IBS Daejeon)\n\nTitle: Swampland bounds on the abelian gauge sectors \nAbstract: In this talk we will derive various bounds on the 0-form and the 1-form abelian gauge sectors of gravitational effective theories in 6 dimensions with minimal supersymmetry. We will start by considering 6-dimensional F-theory vacua with at least one tensor multiplets\, to bound for them the number of the (0-form) U(1) gauge factors as well as the cyclic orders of the 1-form discrete gauge factors. While the two abelian gauge sectors may look rather independent\, we will observe that both are heavily constrained by the solitonic heterotic strings present in the spectrum\, which provide a common intuition for the derived bounds. Building upon the heterotic intuition\, we will also try extending the arena to address analogous bounds for all F-theory vacua in 6 dimensions and even beyond. If time permits\, several applications and future directions of research will be discussed at the end of the talk.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/swampland_41023/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Swampland Seminar
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-Swampland-Seminar-04.10.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230407T120000
DTEND;TZID=America/New_York:20230407T130000
DTSTAMP:20240122T075759Z
CREATED:20230825T085705Z
LAST-MODIFIED:20240122T075759Z
UID:10001304-1680868800-1680872400@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Modular graph forms and iterated integrals in string amplitudes
DESCRIPTION:Algebraic Geometry in String Theory Seminar \nSpeaker: Oliver Schlotterer (Uppsala University) \nTitle: Modular graph forms and iterated integrals in string amplitudes \nAbstract: I will discuss string amplitudes as a laboratory for special functions and period integrals that drive fruitful cross-talk with particle physicists and mathematicians. At genus zero\, integration over punctures on a disk or sphere worldsheet generates multiple zeta values in the low-energy expansion of open- and closed-string amplitudes. At genus one\, closed-string amplitudes introduce infinite families of non-holomorphic modular forms through the integration over torus punctures known as modular graph forms. The latter inspired Francis Brown’s alternative construction of non-holomorphic modular forms in the mathematics literature via iterated integrals\, and I will report on recent progress in clarifying their connection with modular graph forms.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/agst-4723/
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:20230407T100000
DTEND;TZID=America/New_York:20230407T113000
DTSTAMP:20240110T071718Z
CREATED:20230802T170222Z
LAST-MODIFIED:20240110T071718Z
UID:10001174-1680861600-1680867000@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Enhancing Detection of Topological Order by Local Error Correction
DESCRIPTION:Quantum Matter Seminar \nSpeaker: Nishad Maskara (Harvard) \nTitle: Enhancing Detection of Topological Order by Local Error Correction \nAbstract: The exploration of topologically-ordered states of matter is a long-standing goal at the interface of several subfields of the physical sciences. Such states feature intriguing physical properties such as long-range entanglement\, emergent gauge fields and non-local correlations\, and can aid in realization of scalable fault-tolerant quantum computation. However\, these same features also make creation\, detection\, and characterization of topologically-ordered states particularly challenging. Motivated by recent experimental demonstrations\, we introduce a new paradigm for quantifying topological states—locally error-corrected decoration (LED)—by combining methods of error correction with ideas of renormalization-group flow. Our approach allows for efficient and robust identification of topological order\, and is applicable in the presence of incoherent noise sources\, making it particularly suitable for realistic experiments. We demonstrate the power of LED using numerical simulations of the toric code under a variety of perturbations\, and we subsequently apply it to an experimental realization of a quantum spin liquid using a Rydberg-atom quantum simulator.  Finally\, we illustrate how LED can be applied to more general phases including non-abelian topological orders. \n 
URL:https://live-hu-cmsa-222.pantheonsite.io/event/qm_4723/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-QMMP-04.07.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230406T093000
DTEND;TZID=America/New_York:20230406T103000
DTSTAMP:20240119T051939Z
CREATED:20230818T042449Z
LAST-MODIFIED:20240119T051939Z
UID:10001259-1680773400-1680777000@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Rough solutions of the relativistic Euler equations
DESCRIPTION:General Relativity Seminar \nSpeaker: Sifan Yu\, Vanderbilt University \nTitle: Rough solutions of the relativistic Euler equations \nAbstract: I will discuss recent works on the relativistic Euler equations with dynamic vorticity and entropy. We use a new formulation of the equations\, which has geo-analytic structures. In this geometric formulation\, we decompose the flow into geometric “sound-wave part” and “transport-div-curl part”. This allows us to derive sharp results about the dynamics\, including the existence of low-regularity solutions. Then\, I will discuss the results of rough solutions of the relativistic Euler equations and the role that nonlinear geometric optics plays in the framework. Our main result is that the Sobolev norm $H^{2+}$ of the variables in the “wave-part” and the H\”older norm $C^{0\,0+}$ of the variables in the “transport-part” can be controlled in terms of initial data for short times. We note that the Sobolev norm assumption $H^{2+}$ is the optimal result for the variables in the “wave-part.” This talk will include the main ideas of the proof\, as well as a comparison of the relativistic and non-relativistic scenarios.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/gr_4623/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:General Relativity Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230405T153000
DTEND;TZID=America/New_York:20230405T163000
DTSTAMP:20240111T070226Z
CREATED:20230807T173206Z
LAST-MODIFIED:20240111T070226Z
UID:10001193-1680708600-1680712200@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Sampling from the SK and mixed p-spin measures with stochastic localization
DESCRIPTION:Probability Seminar \n\nSpeaker: Ahmed El Alaoui (Cornell) \nTitle: Sampling from the SK and mixed p-spin measures with stochastic localization \nAbstract: I will present an algorithm which efficiently samples from the Sherrington-Kirkpatrick (SK) measure with no external field at high temperature. The approach is based on the stochastic localization process of Eldan\, together with a subroutine for computing the mean vectors of a family of measures tilted by an appropriate external field. Conversely\, we show that no ‘stable’ algorithm can approximately sample from the SK measure at low temperature. Time permitting\, we discuss extensions to the p-spin model. This is based on a joint work with Andrea Montanari and Mark Sellke.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/probability-4523/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Probability Seminar
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-Probability-Seminar-04.05.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230404T120000
DTEND;TZID=America/New_York:20230404T130000
DTSTAMP:20240228T092930Z
CREATED:20230817T171014Z
LAST-MODIFIED:20240228T092930Z
UID:10001240-1680609600-1680613200@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Optimal Dynamic Allocation: Simplicity through Information Design
DESCRIPTION:Member Seminar \nSpeaker: Faidra Monachou \nTitle: Optimal Dynamic Allocation: Simplicity through Information Design \nAbstract: We study dynamic nonmonetary markets where objects are allocated to unit-demand agents with private types. An agent’s value for an object is supermodular in her type and the quality of the object\, and her payoff is quasilinear in her waiting cost. The social planner’s objective is a linear combination of allocative efficiency (i.e.\, the sum of values) and welfare (i.e.\, the sum of payoffs). We identify the optimal mechanism in the class of direct-revelation mechanisms that elicit agents’ types and assign them to objects over time. We show that\, when the social planner can design the information disclosed to the agents about the objects\, the optimal mechanism has a simple implementation: a first-come first-served waitlist with deferrals. In this implementation\, the information disclosed about each object is an interval containing the object quality\, rather than the exact quality. These intervals partition the quality space. We also show that when the planner’s objective weight on welfare increases\, these intervals become coarser\, and optimal disclosure policies less informative. A direct corollary is that mechanisms that achieve higher welfare also induce lower distributional inequality\, in terms of the Lorenz order.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/member-seminar-4423/
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:20230403T110000
DTEND;TZID=America/New_York:20230403T120000
DTSTAMP:20240122T052041Z
CREATED:20230817T181822Z
LAST-MODIFIED:20240122T052041Z
UID:10001280-1680519600-1680523200@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Black hole microstate counting from the gravitational path integral
DESCRIPTION:Colloquium \nSpeaker: Luca Iliesiu\, Stanford \nTitle: Black hole microstate counting from the gravitational path integral \nAbstract: Reproducing the integer count of black hole micro-states from the gravitational path integral is an important problem in quantum gravity. In the first part of the talk\, I will show that\, by using supersymmetric localization\, the gravitational path integral for 1/16-BPS black holes in supergravity can reproduce the index obtained in the string theory construction of such black holes. A more refined argument then shows that not only the black hole index but also the total number of black hole microstates within an energy window above extremality that is polynomially suppressed in the charges also matches this string theory index. In the second part of the talk\, I will present a second perspective on this state count and show how the BPS Hilbert space can be obtained by directly preparing states using the gravitational path integral. While such a preparation naively gives rise to a Hilbert space of BPS states whose dimension is much larger than expected\, I will explain how non-perturbative corrections in the overlap of such states are again responsible for reproducing the correct dimension of the Hilbert space.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/colloquium-4323/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-Colloquium-04.03.2023.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230330T130000
DTEND;TZID=America/New_York:20230330T140000
DTSTAMP:20240228T084556Z
CREATED:20230824T182516Z
LAST-MODIFIED:20240228T084556Z
UID:10002748-1680181200-1680184800@live-hu-cmsa-222.pantheonsite.io
SUMMARY:The Role of Orientational Order in Development
DESCRIPTION:Active Matter Seminar\n\n\nSpeaker: Mark Bowick\, Kavli Institute for Theoretical Physics\, UCSB \nTitle: The Role of Orientational Order in Development \nAbstract: Morphogenesis\, the process through which genes generate form\, establishes tissue scale order as a template for constructing the complex shapes of the body plan. The extensive growth required to build these ordered substrates is fueled by cell proliferation\, which\, naively\, should disrupt order. Understanding how active morphogenetic mechanisms couple cellular and mechanical processes to generate order remains an outstanding question in animal development. I will review the statistical mechanics of orientational order and discuss the observation of a fourfold orientationally ordered phase (tetratic) in the model organism Parhyale hawaiensis. I will also discuss theoretical mechanisms for the formation of orientational order that require both motility and cell division\, with support from self-propelled vertex models of tissue. The aim is to uncover a robust\, active mechanism for generating global orientational order in a non-equilibrium system that then sets the stage for the development of shape and form.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/am-33023/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Active Matter Seminar
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-Active-Matter-Seminar-03.30.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230330T093000
DTEND;TZID=America/New_York:20230330T223000
DTSTAMP:20240118T101402Z
CREATED:20230818T042141Z
LAST-MODIFIED:20240118T101402Z
UID:10001258-1680168600-1680215400@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Gravitational perturbations near to extreme Kerr
DESCRIPTION:General Relativity Seminar \nSpeaker: Alejandra Castro (University of Cambridge) \nTitle: Gravitational perturbations near to extreme Kerr \nAbstract: Gravitational perturbations of a black hole illustrate the invaluable synergy between theory\, experiment\, and numerical simulations in general relativity. A recent development in the theory side has been the identification of the relevant degrees of freedom describing the low energy physics driving a black hole away from extremality.  For simple cases\, this low energy sector determines important aspects of the gravitational backreaction\, and several properties that are key to our microscopic (quantum) understanding of black hole physics.\n\nIn this talk I will discuss these developments in the context of the (near-)extreme Kerr black hole. In particular\, I will revisit the spectrum of linear axisymmetric gravitational perturbations of this black hole. The aim is to characterise those perturbations that are responsible for the deviations away from extremality\, and to contrast them with the linearized perturbations treated in the Newman-Penrose formalism. I will show that for Kerr the low-lying mode sector is subtle and intricate—features that their charged spherical symmetric cousins do not display. This unveils new clues on how to decode a microscopic\, and holographic\, understanding of the Kerr black hole.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/gr_33023/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:General Relativity Seminar
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-GR-Seminar-03.30.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230329T123000
DTEND;TZID=America/New_York:20230329T133000
DTSTAMP:20240216T102824Z
CREATED:20230817T181436Z
LAST-MODIFIED:20240216T102824Z
UID:10001279-1680093000-1680096600@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Scattering amplitudes in quantum field theory
DESCRIPTION:Speaker: Ruth Britto (Trinity College Dublin) \nTitle: Scattering amplitudes in quantum field theory \nAbstract: Particle collider experiments require a detailed description of scattering events\, traditionally computed through sums of Feynman diagrams. However\, it is not practical to evaluate Feynman diagrams directly for all significant scattering processes. Moreover\, adding all diagrams reveals many cancellations: scattering amplitudes in theories such as QCD take remarkably simple forms. This simplicity is a clue that the perturbative theory is perhaps best understood without reference to Feynman diagrams. In fact\, it has recently become possible to explain some of this simplicity. I will show how to derive many amplitudes efficiently and elegantly\, and propose taming the remaining complexity with ideas drawn from combinatorics and geometry.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/collquium-32923/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-Colloquium-03.29.2023.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230328T120000
DTEND;TZID=America/New_York:20230328T130000
DTSTAMP:20240118T070227Z
CREATED:20230817T170827Z
LAST-MODIFIED:20240118T070227Z
UID:10001239-1680004800-1680008400@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Monotonicity of quasilocal mass for asymptotically flat Riemannian manifolds
DESCRIPTION:Member Seminar \nSpeaker: Jue Liu \nTitle: Monotonicity of quasilocal mass for asymptotically flat Riemannian manifolds \nAbstract: The study of quasilocal mass in general relativity has a long history. In previous papers by many authors we have a deep understanding of the properties of quasilocal mass such as positivity\, rigidity and asymptotics etc. In this talk I will focus on the monotonicity of quasilocal mass\, which means the quasilocal mass of a finite region is smaller than that of a larger region containing the previous region. Motivated by the definition of Bartnik mass and Brown-York mass\, we define a new quasilocal mass using the Hamilton method. With this definition\, we derive the sufficient condition such that the quasilocal mass is monotonic. As an application I will also discuss the relationship with the Bartnik conjecture\, that is under what conditions there will be a static extension to the given Bartnik data.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/member-seminar-32823/
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:20230327T110000
DTEND;TZID=America/New_York:20230327T120000
DTSTAMP:20240215T101847Z
CREATED:20230730T190429Z
LAST-MODIFIED:20240215T101847Z
UID:10001160-1679914800-1679918400@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Recent developments on the tidal Love numbers of black holes
DESCRIPTION:Swampland Seminar \nSpeaker: Valerio De Luca (UPenn)\n\nTitle: Recent developments on the tidal Love numbers of black holes \nAbstract: Tidal Love numbers describe the deformability of compact objects under the presence of external tidal perturbations\, and are found to be exactly zero for black holes in pure General Relativity. This property is however fragile\, since they receive corrections from higher-order derivative terms in the theory. We show that the tidal deformability of neutral black holes is constrained by the Weak Gravity Conjecture.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/swampland_32723/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Swampland Seminar
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-Swampland-Seminar-03.27.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230323T133000
DTEND;TZID=America/New_York:20230323T143000
DTSTAMP:20240118T100327Z
CREATED:20230818T041454Z
LAST-MODIFIED:20240118T100327Z
UID:10001257-1679578200-1679581800@live-hu-cmsa-222.pantheonsite.io
SUMMARY:New Phases of N=4 SYM
DESCRIPTION:General Relativity Seminar \nSpeaker: Prahar Mitra (University of Cambridge) \nTitle: New Phases of N=4 SYM \nAbstract: We construct new static solutions to gauged supergravity that\, via the AdS/CFT correspondence\, are dual to thermal phases in N=4 SYM at finite chemical potential. These solutions dominate the micro-canonical ensemble and are required to ultimately reproduce the microscopic entropy of AdS black holes. These are constructed in two distinct truncations of gauged supergravity and can be uplifted to solutions of type IIB supergravity. Together with the known phases of the truncation with three equal charges\, our findings permit a good understanding of the full phase space of SYM thermal states with three arbitrary chemical potentials. We will also discuss the status of hairy supersymmetric black hole solutions in this theory. \nBased on: https://arxiv.org/pdf/2207.07134.pdf [hep-th]
URL:https://live-hu-cmsa-222.pantheonsite.io/event/gr_32323/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:General Relativity Seminar
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-GR-Seminar-03.23.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230322T123000
DTEND;TZID=America/New_York:20230322T133000
DTSTAMP:20240216T104444Z
CREATED:20230817T181152Z
LAST-MODIFIED:20240216T104444Z
UID:10001278-1679488200-1679491800@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Synchronization in a Kuramoto Mean Field Game
DESCRIPTION:Speaker: Mete Soner (Princeton University) \nTitle: Synchronization in a Kuramoto Mean Field Game \nAbstract:  Originally motivated by systems of chemical and biological oscillators\, the classical Kuramoto model has found an amazing range of applications from neuroscience to Josephson junctions in superconductors\, and has become a  key mathematical model to describe self organization in complex systems. These autonomous oscillators are coupled through a nonlinear interaction term which plays a central role in the long term behavior of the system. While the system is not synchronized when this term is not sufficiently strong\, fascinatingly\, they exhibit an abrupt transition to a full synchronization above a critical value of the interaction parameter.  We explore this system in the mean field formalism.  We treat the system of oscillators as an infinite particle system\, but instead of positing the dynamics of the particles\, we let the individual particles determine endogenously their behaviors by minimizing a cost functional and eventually\, settling in a Nash equilibrium.  The mean field game also exhibits a bifurcation from incoherence to self-organization.  This approach has found interesting applications including circadian rhythms and jet-lag recovery.  This is joint work with Rene Carmona of Princeton and Quentin Cormier of INRIA\, Paris.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/collquium-32223/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-Colloquium-03.22.2023.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230321T120000
DTEND;TZID=America/New_York:20230321T130000
DTSTAMP:20240118T070105Z
CREATED:20230817T170644Z
LAST-MODIFIED:20240118T070105Z
UID:10001238-1679400000-1679403600@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Quantum Gravity constraints beyond asymptotic regimes
DESCRIPTION:Member Seminar \nSpeaker: Max Wiesner \nTitle: Quantum Gravity constraints beyond asymptotic regimes \nAbstract: Not every effective field theory that is consistent in the absence of gravity can be completed to a consistent theory of quantum gravity. The goal of the Swampland program is to find general criteria that distinguish effective field theories\, that can be obtained as a low-energy approximation of quantum gravity\, from those that are inconsistent in the presence of gravity. These criteria are oftentimes motivated by patterns observed in explicit compactifications of perturbative string theory and have passed many non-trivial tests in asymptotic regions of the field space such as\, e.g.\, weak coupling limits. Still\, the Swampland criteria should equally apply to effective theories that do not arise in asymptotic regions of the field space of string theory compactifications. In this talk I will summarize some of my recent works that studies the interior of regions of the field space of string theory in the context of the Swampland program.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/member-seminar-32123/
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:20230317T100000
DTEND;TZID=America/New_York:20230317T113000
DTSTAMP:20240228T091308Z
CREATED:20230802T165348Z
LAST-MODIFIED:20240228T091308Z
UID:10001171-1679047200-1679052600@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Tensorial TQFT and disentangling modular Walker-Wang models
DESCRIPTION:Quantum Matter Seminar \nSpeaker: Andreas Bauer  (Freie Universität Berlin) \nTitle: Tensorial TQFT and disentangling modular Walker-Wang models \nAbstract: I will introduce simple “tensorial” definitions for many algebraic and categorical structures appearing in the classification of topological phases of matter. Such “tensorial TQFTs” will be defined as maps that associate tensors to geometric/topological objects of some type\, subject to gluing axioms. Tensorial TQFTs are very directly related to microscopic physical models in terms of discrete path integrals. I will use those tensorial definitions to construct invertible boundaries which disentangle modular Walker-Wang models. \n 
URL:https://live-hu-cmsa-222.pantheonsite.io/event/qm_31723/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Quantum Matter
END:VEVENT
END:VCALENDAR