There are no events at the Simons Center today. Here are the events for this week

Tuesday, April 6th, 2021

SCGP Group Meeting - Physics

Time: 1:00 PM - 2:00 PM

Location:

**Title:**Mean string field theory: Landau-Ginzburg theory for 1-form symmetries**Speaker:**Nabil Iqbal**Abstract:**Just as conventional global symmetries result in a conserved particle number, higher-form global symmetries are associated with a conserved density of higher dimensional objects, such as strings or branes. I will present an overview of the applications of such symmetries and discuss the prospect of using them to enlarge the usual Landau classification of the phases of matter. I will then describe the construction of a continuum Landau-Ginzburg theory to describe the spontaneous breaking of a higher-form symmetry. As the order parameter is an operator that creates a string, the framework can be thought of as a kind of "mean string field theory" that provides a non-perturbative description where effective strings can be created and destroyed. I will argue that many aspects of higher form symmetries — including the phase structure, the behavior of line operators, and the dynamics of Goldstone modes — can be transparently understood in this framework.
Wednesday, April 7th, 2021

**Math Event:**Algebraic Geometry: Dori Bejleri - Stable pairs with a twist

Time: 3:00 PM - 4:00 PM

Location: Online

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**Title:**Stable pairs with a twist**Speaker:**Dori Bejleri [Harvard University]**Abstract:**The notion of a stable log variety or stable pair (X,D) is the higher dimensional analogue of a stable pointed curve. The existence of a proper moduli space of stable pairs in any dimension has been established thanks to the last several decades of advancements in the minimal model program. However, the notion of a family of stable pairs remains quite subtle, and in particular a deformation-obstruction theory for this moduli problem is not known. Building on the work of Abramovich-Hassett, I will describe an approach to this question using a certain Deligne-Mumford stack canonically associated to the stable pair (X,D) and mention some applications of this approach. This is joint work with G. Inchiostro.View Details

Thursday, April 8th, 2021

SCGP Group Meeting - Math

Time: 1:00 PM - 2:00 PM

Location:

**Title:**Can discretization of the spatial continuum reveal algebra underlying perturbative quantization?**Speaker:**Dennis Sullivan**Abstract:**There is a sequence of finite dimensional algebras and differential with a deformed rule for differencing a product described in "Approximations in difference calculus to the continuum calculus" Lawrence,Ranade and Sullivan (Atiyah memorial Volume). The differential has canonical higher order bracket perturbations at each scale (called infinitesimal cumulants) and there are higher order mappings between scales based on traditional cumulants. The goal now is to fit this naturally occurring structure on euclidean space endowed with finer and finer lattices and overlapping cubical decompositions with the "perturbative formal power series in the scale" enhancement described for the continuum picture in "Renormalization and effective field theory " (Kevin Costello book). This process is obstructed in general but can be tried for any equation of motion (EOM) described by an action principle. The first objective is to apply this to the computations of 3D hydrodynamics on periodic three space by adding these perturbative corrections to the EOM written in the lattice difference calculus. Takeaway: 1)There is a new feature in the discretizations here based on Poincare's dual cell ideas. 2) If this works to the end one will see an algebraic formalism of physical quantization arising directly from the lattice difference calculus approximations to the continuum calculus. 3) Plus there will be improved computations of 3D fluids. (Based on collaboration with Daniel An, Theo Drivas and Ruth Lawrence.)**YITP Event:**YITP Seminar (Masha Baryakhtar)

Time: 3:00 PM - 4:30 PM

Location:

**Speaker:**bsp;Masha Baryakhtar (NYU)**Time:**Thursday April 8th, 3pm

**Abstract:**bsp;I will discuss how black holes can become nature's laboratories for ultralight axions. When a boson's Compton wavelength is comparable to the horizon size of a black hole, energy and angular momentum from the black hole are converted into exponentially growing clouds of bosons, creating a gravitational atom in the sky. Previously open parameter space of axions can be constrained by observations of rapidly spinning black holes. Such black hole-axion `gravitational atoms' can also source up to thousands of monochromatic gravitational wave signals visible in LIGO and VIRGO observatories. If the axions interact with one another, instead of gravitational waves, black holes populate the universe with axion waves that may be detectable in laboratory experiments designed for axion dark matter searches.**Zoom Link:**https://stonybrook.zoom.us/j/99456035345?pwd=TVZMSldHTmEyZWQrc21EZ1I2emdsUT09**
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**Math Event:**Math Colloquium: Bryna Kra - Symmetries in symbolic dynamics

Time: 4:30 PM - 5:30 PM

Location: Online

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**Title:**Symmetries in symbolic dynamics**Speaker:**Bryna Kra [Northwestern University]**Abstract:**Originating in the work of Hadamard in the 1890's on the coding of geodesic flow, symbolic dynamics has become a key tool for studying topological, smooth, and measurable dynamical systems. The automorphism group of a symbolic system capture its symmetries, reflecting the dynamical behavior and the complexity of the system. I will give an overview of relations among dynamical properties of the system (such as periodicity, minimality and transitivity), algebraic properties (such as the automorphism group), and combinatorial problems, all of which quickly lead to open questions.View Details

**Friday, April 9th, 2021**