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marcus
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Sep17-09, 07:46 PM
Astronomy
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PF Gold
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Here is the abstract for Herbert Hamber's talk.
Quantum Gravitation and the Renormalization Group
Herbert Hamber
"In my talk I will provide an overview of the applications of Wilson's modern renormalization group (RG) to problems in quantum gravity. I will first discuss the development of the RG for continuum gravity within the framework of Feynman's covariant path integral approach. Then I will discuss a number of issues that arise when implementing the path integral approach with an explicit lattice UV regulator, and later how non-perturbative RG flows and universal non-trivial scaling dimensions can in principle be extracted from these calculations. Towards the end I will discuss recent attempts at formulating RG flows for gravitational couplings within the framework of a set of manifestly covariant, but non-local, effective field equations suitable for quantum cosmology."
May 13, 2009 -
http://pirsa.org/09050006/

He comes across as somewhat arrogant and aggressive against the other competing approaches like Loop and including also Loll's CDT. I think this is all right---he is just playing hardball with his close competitors. And until recently I think his research was not so visible as either of those. Since the talk is at Perimeter and Lee Smolin and Laurent Freidel are in the audience, they are among those asking questions.

The slides are much the same as the ones he used for the invited plenary talk in Paris on 14 July, in a session chaired by Ashtekar, where Laurent Freidel and Juan Maldacena also gave talks.
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Rovelli gave his "new look" LQG talk today at the Corfu school. It seems to me that LQG gets redefined from time to time. The current version is apt to be slightly different and we won't know in what way until these 5 one-hour talks are online. Here for reference is the abstract of the lecture series that started today:

Carlo Rovelli

Covariant loop quantum gravity and its low-energy limit

"I present a new look on Loop Quantum Gravity, aimed at giving a better grasp on its dynamics and its low-energy limit. Following the highly succesful model of QCD, general relativity is quantized by discretizing it on a finite lattice, quantizing, and then studying the continuous limit of expectation values. The quantization can be completed, and two remarkable theorems follow. The first gives the equivalence with the kinematics of canonical Loop Quantum Gravity. This amounts to an independent re-derivation of all well known Loop Quantum gravity kinematical results. The second the equivalence of the theory with the Feynman expansion of an auxiliary field theory. Observable quantities in the discretized theory can be identifies with general relativity n-point functions in appropriate regimes. The continuous limit turns out to be subtly different than that of QCD, for reasons that can be traced to the general covariance of the theory. I discuss this limit, the scaling properties of the theory, and I pose the problem of a renormalization group analysis of its large distance behavior."

http://www.physics.ntua.gr/corfu2009/qg.html
http://www.physics.ntua.gr/corfu2009...eekSchool.html