Advances in ChernSimons Classical and Quantum Gravity
Institute for Computational and Experimental Research in Mathematics (ICERM)
May 6, 2022  May 8, 2022
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Friday, May 6, 2022

4:20  4:30 pm EDTWelcome11th Floor Lecture Hall
 Stephon Alexander, Brown University
 Brendan Hassett, ICERM/Brown University

4:30  5:15 pm EDTChernSimons and Parity in Cosmology11th Floor Lecture Hall
 Speaker
 Marc Kamionkowski, Johns Hopkins University
 Session Chair
 Stephon Alexander, Brown University
Abstract
The appearance of parity breaking in the electroweak sector, the notion of unification of fundamental forces, and the expectation that a deeper understanding of the Big Bang requires new physics all lead us to consider the search for cosmological signatures of parity breaking. I will review an array of paritybreaking signatures built from largescalestructure and cosmicmicrowavebackground data and attempt to connect them models for new physics, most rooted on the inclusion of ChernSimons terms in the Lagrangian.

5:30  6:45 pm EDTReception  featuring Jazz by Melvin GibbsReception  11th Floor Collaborative Space
Saturday, May 7, 2022

9:00  9:45 am EDTSimulating black hole binaries in quadratic gravity11th Floor Lecture Hall
 Speaker
 Helvi Witek, University of Illinois at UrbanaChampaign
 Session Chair
 Stephon Alexander, Brown University
Abstract
With the advent of gravitational wave astronomy we are now in a perfect position to confront the multitude of beyondGR theories, typically invoked to connect to quantum gravity paradigms, with actual observations in the strongfield regime of gravity. A necessary ingredient to do so, either via theoryspecific tests or to inform parametrized approaches, are theoretical models describing the dynamics of compact binaries in extensions of general relativity. In this talk I will present recent results on modelling black hole binaries in scalar GaussBonnet gravity, that involves highercurvature corrections to Einstein's equations. As the parityeven cousin of dynamical ChernSimons gravity, they share common features they may act as guide to phenomenology in dCS. For example, black holes can acquire scalar hair or spontaneously scalarize. Thus, binaries thereof yield new phenomena such as additional scalar radiation, dephasing of the gravitational wave signal and dynamical (de)scalarization upon merger.

10:00  10:45 am EDTWhen ChernSimons meets quantum gravity: A tale about the Kodama state.11th Floor Lecture Hall
 Speaker
 Laurent Freidel, Perimeter Institute for Theoretical Physics
 Session Chair
 Stephon Alexander, Brown University
Abstract
In this talk, I will introduce the perturbative and nonperturbative canonical quantization of gravity in the presence of a cosmological constant. I will review the advantages of the selfdual formulation of gravity and present the ChernSimons states discovered by Kodama. I will discuss some successes and some puzzles associated with this state. I will present the construction of the physical scalar product, which provides a nonperturbative solution to the reality conditions and solve a longstanding puzzle. Finally, I will discuss some of the challenges that these results raise.

11:00  11:15 am EDTCoffee Break11th Floor Collaborative Space

11:15 am  12:00 pm EDTQuantum gravity here and now, and at the end of the world11th Floor Lecture Hall
 Speaker
 Joao Magueijo, Imperial College London
 Session Chair
 Stephon Alexander, Brown University
Abstract
I review a recent approach to connecting quantum gravity and the real world by deconstantizing the constants of nature, and using their conjugate as a time variable. This is nothing but a generalization of unimodular gravity. The wave functions are then packets of plane waves moving in a space that generalizes the ChernSimons functional. For appropriate states they link up with classical cosmology in the appropriate limit. There are however deviations, namely during the matter to Lambda transition, raising the possibility that quantum gravity could be in action here and now. At the other extreme I show how this approach can be used to resolve the cosmological singularity, and perhaps more.

12:15  1:30 pm EDTLunch/Free Time

1:30  1:50 pm EDTAspects of Rotating Black Holes in Dynamical ChernSimons Gravity'11th Floor Lecture Hall
 Speaker
 Leah Jenks, Brown University
 Session Chair
 Stephon Alexander, Brown University

1:55  2:15 pm EDTWavefunctions of the universe and quantum torsion.11th Floor Lecture Hall
 Speaker
 Gabriel Herczeg, Brown University
 Session Chair
 Stephon Alexander, Brown University

2:20  2:40 pm EDTBlack Holes, Neutron Stars and Gravitational Waves in ChernSimons gravity and beyond11th Floor Lecture Hall
 Speaker
 Kent Yagi, University of Virginia
 Session Chair
 Stephon Alexander, Brown University

2:45  3:15 pm EDTCoffee Break11th Floor Collaborative Space

3:15  4:00 pm EDTThe numerical dynamical renormalization group: controlling secular growth (in numerical simulations of dCS gravity)11th Floor Lecture Hall
 Speaker
 Leo Stein, University of Mississippi
 Session Chair
 Nicolas Yunes, University of Illinois Urbana Champaign

4:10  4:45 pm EDTPanel Discussion11th Floor Lecture Hall
 Panelists
 Stephon Alexander, Brown University
 Laurent Freidel, Perimeter Institute for Theoretical Physics
 Joao Magueijo, Imperial College London
 Lee Smolin, Perimeter Institute for Theoretical Physics
 Nicolas Yunes, University of Illinois Urbana Champaign
Sunday, May 8, 2022

9:00  9:45 am EDTInflation with ChernSimons interactions11th Floor Lecture Hall
 Speaker
 Peter Adshead, University of Illinois UrbanaChampaign
 Session Chair
 Nicolas Yunes, University of Illinois Urbana Champaign

10:00  10:45 am EDTChernSimon states as the description of the past of an event in the causal theory of views11th Floor Lecture Hall
 Speaker
 Lee Smolin, Perimeter Institute for Theoretical Physics
 Session Chair
 Nicolas Yunes, University of Illinois Urbana Champaign
Abstract
This talk describes a continuation of the program of causal views, in which the world consists of nothing but a vast number of partial views of its past. Each view is associated to an event, and is a representation of the immediate causal past of that event. These consists mainly of processes that transfer energy, momentum and other charges to it from its past events.There is fundamentally no space or spacetime, just a large number of events, which are the causes of events to come.
We show that in a relativistic version of the theory a view of an event is represented by a quantum state. of a ChernSimons on an Npunctured sphere. N is the number of immediate past events; the cosmological constant is related to the level by
k = 16 \pi /G \Lambda
Momentum and energy are fundamental, and are conserved under their transformation from present events to future events. As a result Minkowski spacetime emerges, in a way that preserves causal relations. The locality of events as constructed in the emergent spacetime is a consequence of the conservation of energymomentum fundamentally. 
11:00  11:30 am EDTClosing Remarks / DiscussionClosing Remarks  11th Floor Lecture Hall

11:30 am  12:00 pm EDTCoffee Break10th Floor Collaborative Space
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