Madrid’s Polygonal Gravity Seminar Series
Venue&Time: Red Room / 11:30 / 15:00
PROGRAM:
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11:00 Welcome coffee
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11:30h First Talk
Speaker: Jelle Hartong (Edinburgh U.)
Title: The Geometry of Gravitational Radiation
Abstract: This talk concerns asymptotically flat vacuum solutions of GR in
4 spacetime dimensions. The asymptotics of such metrics is quite intricate
and depends on how we approach infinity. If we follow null geodesics we
end up at future null infinity. This is where massless fields, including
gravitational radiation ends up. In this talk we will study the metric
near future null infinity with an emphasis on geometrical structures that
emerge in that part of the spacetime.
Future null infinity of an asymptotically flat spacetime is a conformal
Carroll manifold. I will not assume any familiarity with Carroll geometry
and explain the relevant geometrical notions as we go along. We will
consider asymptotic solutions to the 4D vacuum Einstein equations where
future null infinity is endowed with the most general Carroll metric data
that is allowed by the Einstein equations. This can be used to define an
energy-momentum tensor (EMT) at future null infinity by varying a suitably
renormalised action with respect to the boundary Carroll metric data. It
is shown that the Ward identities obeyed by this boundary EMT agree with
the Bondi loss equations that describe the loss of energy and momentum due
to the emission of gravitational waves. The metric near future null
infinity can be formulated in terms of a Cartan geometry based on the
conformal Carroll algebra. The non-vanishing curvatures of said algebra
dictate how radiative the spacetime is. For example, the vacuum degeneracy
is described by a flat conformal Carroll connection. We will see that the
Bondi loss equations can be rewritten as flux-balance laws where the
fluxes are determined by the Cartan geometry for the conformal Carroll
algebra.
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15:00h Second Talk
Speaker: Eric A. Bergshoeff (U. of Groningen)
Title: Massive gravity in the lab
Abstract: In this talk I will discuss a connection between the so-called
chiral massive GMP spin-2 mode in the Fractional Quantum Hall effect and a
three-dimensional (one time and two space) relativistic massive spin-2
field in quantum field theory. In particular, I will show how the spin-2
GMP mode follows by taking a special non-relativistic limit of linearized
three-dimensional massive gravity which are the planar Fierz-Pauli
equations. I will discuss how these results can be generalized to integer
higher-spins and will present results for half-integer spins as well.
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16:15 Farewell coffee
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More information about these and following monthly seminars can be found at the
webpage
https://sites.google.com/view/polygrav
We very much hope to see you there! (No registration is needed)
Fernando Barbero (IEM), Guillermo Mena (IEM), Luis Garay (UCM),
Mercedes Martin-Benito (UCM), Daniele Oriti (UCM), Tomas Ortin(IFT), Francesca
Vidotto (IEM), Eduardo Villaseñor (UC3M)