EFTFORLQG · Effective Field Theory for Loop Quantum Gravity

Effective Field Theory for Loop Quantum Gravity

The objective of this research project is to develop the Loop approach to Quantum Gravity, assess its physical viability as a description of gravity at the Planck scale, and develop approximation schemes for extracting low-energy predictions from the theory. The project is articulated in three parts: (a) identify coherent states peaked on a classical geometry of space; (b) study the dynamics of semiclassical states, using the spin foam framework; (c) apply the formalism developed in (a)-(b) to specific physics problems like: graviton propagation on flat space, black hole entropy, cosmological dynamics. The methods involved in the analysis are: semiclassical expansions (WKB) and effective field theory techniques, applied to the background independent structure of Loop Quantum Gravity. Thanks to CPT 's exceptional scientific environment, to C.Rovelli's excellent skills in research training, and to the EU contribution , the results of the project have largely outperformed the original expectations in each of its three parts. In particular, reaching the stage of part (c) has contributed to establishing Loop Quantum Gravity as a strong candidate for the description of physics at the Planck scale - a description which provides a quantum picture of space-time at such microscopic scale, which is compatible with the present knowledge in quantum field theory and which may predict experimental signatures to be investigated in future. The results of the project have been published in refereed journals (6 Phys.Rev.D, 1 Phys.Rev.Lett., 1 Nature, 3 Class.Quant.Grav., 1 Nucl.Phys.B) and have been presented at the major international conferences in quantum gravity in the period 2010-2011. Background independent quantum gravity is becoming a structural part of research in theoretical physics in various countries of the European Union. By addressing within Loop Quantum Gravity the key question of the extraction of physical predictions from background independent theories, the project has further increased this competitiveness and CPT's leadership in the whole sector of theoretical physics.

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