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Complex Ashtekar Variables and Reality Conditions for Holst’s Action
From the Holst action in terms of complex valued Ashtekar variables, additional reality conditions mimicking the linear simplicity constraints of spin-foam gravity are found. In quantum theory with
Horizon energy as the boost boundary term in general relativity and loop gravity
We show that the near-horizon energy introduced by Frodden, Ghosh and Perez arises from the action for general relativity as a horizon boundary term. Spin foam variables are used in the analysis. The
Twistorial structure of loop-gravity transition amplitudes
The spin foam formalism provides transition amplitudes for loop quantum gravity. Important aspects of the dynamics are understood, but many open questions are pressing on. In this paper we address
Twistorial phase space for complex Ashtekar variables
We generalize the SU(2) spinor framework of twisted geometries developed by Dupuis, Freidel, Livine, Speziale and Tambornino to the Lorentzian case, that is the group . We show that the phase space
Spin connection of twisted geometry
Twisted geometry is a piecewise-flat geometry less rigid than Regge geometry. In Loop Gravity, it provides the classical limit for each step of the truncation utilized in the definition of the
Cosmological evolution as squeezing: a toy model for group field cosmology
We present a simple model of quantum cosmology based on the group field theory (GFT) approach to quantum gravity. The model is formulated on a subspace of the GFT Fock space for the quanta of
Fock Representation of Gravitational Boundary Modes and the Discreteness of the Area Spectrum
In this article, we study the quantum theory of gravitational boundary modes on a null surface. These boundary modes are given by a spinor and a spinor-valued two-form, which enter the gravitational
First-order formulation of teleparallel gravity and dual loop gravity
There are at least two ways to encode gravity into geometry: Einstein's general theory of relativity (GR) for the metric tensor, and teleparallel gravity, where torsion as opposed to curvature
Null infinity as an open Hamiltonian system
  • W. Wieland
  • Physics
    Journal of High Energy Physics
  • 3 December 2020
Abstract When a system emits gravitational radiation, the Bondi mass decreases. If the Bondi energy is Hamiltonian, it can thus only be a time-dependent Hamiltonian. In this paper, we show that the
Discrete gravity as a topological field theory with light-like curvature defects
A bstractI present a model of discrete gravity as a topological field theory with defects. The theory has no local degrees of freedom and the gravitational field is trivial everywhere except at a