Daniele Pranzetti

Black hole entropy from the SU(2)-invariant formulation of type I isolated horizons

A detailed analysis of the spherically symmetric isolated horizon system is performed in terms of the connection formulation of general relativity. The system is shown to admit a manifestly SU(2) invariant formulation where the (effective) horizon degrees of freedom are described by an SU(2) Chern-Simons theory. This leads to a more transparent description of the quantum theory in the context of loop quantum gravity and modifications of the form of the horizon entropy.

The SU(2) black hole entropy revisited

We study the state-counting problem that arises in the SU(2) black hole entropy calculation in loop quantum gravity. More precisely, we compute the leading term and the logarithmic correction of both the spherically symmetric and the distorted SU(2) black holes. Contrary to what has been done in previous works, we have to take into account “quantum corrections” in our framework in the sense that the level k of the Chern-Simons theory which describes the black hole is finite and not sent to infinity. Therefore, the new results presented here allow for the computation of the entropy in models where the quantum group corrections are important.

Isolated Horizons and Black Hole Entropy in Loop Quantum Gravity

We review the black hole entropy calculation in the framework of Loop Quantum Gravity based on the quasi-local definition of a black hole encoded in the isolated horizon formalism. We show, by means of the covariant phase space framework, the appearance in the conserved symplectic structure of a boundary term corresponding to a Chern{Simons theory on the horizon and present its quantization both in the U(1) gauge fixed version and in the fully SU(2) invariant one. We then describe the boundary degrees of freedom counting techniques developed for an infinite value of the Chern{Simons level case and, less rigorously, for the case of a finite value. This allows us to perform a comparison between the U(1) and SU(2) approaches and provide a state of the art analysis of their common features and different implications for the entropy calculations. In particular, we comment on different points of view regarding the nature of the horizon degrees of freedom and the role played by the Barbero{Immirzi parameter. We conclude by presenting some of the most recent results concerning possible observational tests for theory.

Canonical quantization of non-commutative holonomies in 2 + 1 loop quantum gravity

In this work we investigate the canonical quantization of 2 + 1 gravity with cosmological constant Λ > 0 in the canonical framework of loop quantum gravity. The unconstrained phase space of gravity in 2 + 1 dimensions is coordinatized by an SU(2) connection A and the canonically conjugate triad field e. A natural regularization of the constraints of 2 + 1 gravity can be defined in terms of the holonomies of

Static Isolated Horizons: SU(2) Invariant Phase Space, Quantization, and Black Hole Entropy

{A_\pm } = A\pm \sqrt {{\Lambda e}}

Geometric temperature and entropy of quantum isolated horizons

. As a first step towards the quantization of these constraints we study the canonical quantization of the holonomy of the connection Aλ = A + λe (for λ ∈

Horizon Entropy from Quantum Gravity Condensates.

\mathbb{R}

Turaev-Viro amplitudes from2+1loop quantum gravity

) on the kinematical Hilbert space of loop quantum gravity. The holonomy operator associated to a given path acts non trivially on spin network links that are transversal to the path (a crossing). We provide an explicit construction of the quantum holonomy operator. In particular, we exhibit a close relationship between the action of the quantum holonomy at a crossing and Kauffman’s q-deformed crossing identity (with

Generalized quantum gravity condensates for homogeneous geometries and cosmology

q = \exp \left( {i\hbar \lambda /2} \right)

Loop gravity string

). The crucial difference is that (being an operator acting on the kinematical Hilbert space of LQG) the result is completely described in terms of standard SU(2) spin network states (in contrast to q-deformed spin networks in Kauffman’s identity). We discuss the possible implications of our result.