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So much potentially important QG reserach appeared this quarter (April-June 2008) that for simplicity I have split the list in two. Papers solely by graduate students and postdocs (no faculty co-author) are discussed in another thread:
https://www.physicsforums.com/showthread.php?t=243004
In my opinion some of the work by junior people this quarter was as significant and innovative as that by faculty. So I urge you to check the other thread out.
Here we are considering papers where at least one author is faculty. Which of the following five papers do you think will prove most valuable, and have the greatest impact on future QG research? I have provided some descriptive comment in parentheses, or else quoted from the authors' abstract or introduction section of the text. Comment from other people would be welcome. How did you decide on your choice? What discussion would you like to hear before making your pick?
1. Florian Conrady, Laurent Freidel
http://arxiv.org/abs/0806.4640
Path integral representation of spin foam models of 4d gravity
"We give a unified description of all recent spin foam models introduced by Engle, Livine, Pereira and Rovelli (ELPR) and by Freidel and Krasnov (FK). We show that the FK models are, for all values of the Immirzi parameter, equivalent to path integrals of a discrete theory and we provide an explicit formula for the associated actions. We discuss the relation between the FK and ELPR models and also study the corresponding boundary states. For general Immirzi parameter, these are given by Alexandrov's and Livine's SO(4) projected states. For 0 <= gamma < 1, the states can be restricted to SU(2) spin networks."
2. Stephon H.S. Alexander, Gianluca Calcagni
http://arxiv.org/abs/0806.4382
Superconducting loop quantum gravity and the cosmological constant
"We argue that the cosmological constant is exponentially suppressed in a candidate ground state of loop quantum gravity as a nonperturbative effect of a holographic Fermi-liquid theory living on a two-dimensional spacetime. Ashtekar connection components, corresponding to degenerate gravitational configurations breaking large gauge invariance and CP symmetry, behave as composite fermions that condense as in Bardeen--Cooper--Schrieffer theory of superconductivity. Cooper pairs admit a description as wormholes on a de Sitter boundary."
3. Abhay Ashtekar, Edward Wilson-Ewing
http://arxiv.org/abs/0805.3511
The covariant entropy bound and loop quantum cosmology
(Proving the important covariant entropy bound in LQG is a major milestone. The original conjecture by Bousso actually fails near the singularity in classic cosmology. LQC supplies what is needed to validate it.)
4. Laurent Freidel
http://arxiv.org/abs/0804.0632
Reconstructing AdS/CFT
"What is AdS/CFT from the point of view of background independent quantum gravity?"
5. J. Ambjorn, K.N. Anagnostopoulos, R. Loll, I. Pushkina
http://arxiv.org/abs/0806.3506
Shaken, but not stirred - Potts model coupled to quantum gravity
"We investigate the critical behaviour of both matter and geometry of the three-state Potts model coupled to two-dimensional Lorentzian quantum gravity in the framework of causal dynamical triangulations. Contrary to what general arguments of the effects of disorder suggest, we find strong numerical evidence that the critical exponents of the matter are not changed under the influence of quantum fluctuations in the geometry, compared to their values on fixed, regular lattices. This lends further support to previous findings that quantum gravity models based on causal dynamical triangulations are in many ways better behaved than their Euclidean counterparts."
https://www.physicsforums.com/showthread.php?t=243004
In my opinion some of the work by junior people this quarter was as significant and innovative as that by faculty. So I urge you to check the other thread out.
Here we are considering papers where at least one author is faculty. Which of the following five papers do you think will prove most valuable, and have the greatest impact on future QG research? I have provided some descriptive comment in parentheses, or else quoted from the authors' abstract or introduction section of the text. Comment from other people would be welcome. How did you decide on your choice? What discussion would you like to hear before making your pick?
1. Florian Conrady, Laurent Freidel
http://arxiv.org/abs/0806.4640
Path integral representation of spin foam models of 4d gravity
"We give a unified description of all recent spin foam models introduced by Engle, Livine, Pereira and Rovelli (ELPR) and by Freidel and Krasnov (FK). We show that the FK models are, for all values of the Immirzi parameter, equivalent to path integrals of a discrete theory and we provide an explicit formula for the associated actions. We discuss the relation between the FK and ELPR models and also study the corresponding boundary states. For general Immirzi parameter, these are given by Alexandrov's and Livine's SO(4) projected states. For 0 <= gamma < 1, the states can be restricted to SU(2) spin networks."
2. Stephon H.S. Alexander, Gianluca Calcagni
http://arxiv.org/abs/0806.4382
Superconducting loop quantum gravity and the cosmological constant
"We argue that the cosmological constant is exponentially suppressed in a candidate ground state of loop quantum gravity as a nonperturbative effect of a holographic Fermi-liquid theory living on a two-dimensional spacetime. Ashtekar connection components, corresponding to degenerate gravitational configurations breaking large gauge invariance and CP symmetry, behave as composite fermions that condense as in Bardeen--Cooper--Schrieffer theory of superconductivity. Cooper pairs admit a description as wormholes on a de Sitter boundary."
3. Abhay Ashtekar, Edward Wilson-Ewing
http://arxiv.org/abs/0805.3511
The covariant entropy bound and loop quantum cosmology
(Proving the important covariant entropy bound in LQG is a major milestone. The original conjecture by Bousso actually fails near the singularity in classic cosmology. LQC supplies what is needed to validate it.)
4. Laurent Freidel
http://arxiv.org/abs/0804.0632
Reconstructing AdS/CFT
"What is AdS/CFT from the point of view of background independent quantum gravity?"
5. J. Ambjorn, K.N. Anagnostopoulos, R. Loll, I. Pushkina
http://arxiv.org/abs/0806.3506
Shaken, but not stirred - Potts model coupled to quantum gravity
"We investigate the critical behaviour of both matter and geometry of the three-state Potts model coupled to two-dimensional Lorentzian quantum gravity in the framework of causal dynamical triangulations. Contrary to what general arguments of the effects of disorder suggest, we find strong numerical evidence that the critical exponents of the matter are not changed under the influence of quantum fluctuations in the geometry, compared to their values on fixed, regular lattices. This lends further support to previous findings that quantum gravity models based on causal dynamical triangulations are in many ways better behaved than their Euclidean counterparts."