Hamburg 2016 – wissenschaftliches Programm

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GR: Fachverband Gravitation und Relativitätstheorie

GR 13: Quantum Gravity III

GR 13.2: Vortrag

Donnerstag, 3. März 2016, 17:05–17:25, VMP6 HS A

Coupled intertwiner dynamics: a toy model for matter on spin foams — •Sebastian Steinhaus — University of Hamburg, II. Institute f. Theoretical Physics, Germany

The universal coupling of matter and gravity is one of the most important features of general relativity. In spin foam models, a path integral approach related to loop quantum gravity, matter couplings have been defined in the past, but little is known about the mutual dynamics. This is tightly related to the fact that the spin foams are defined on a lattice (more precisely a 2-complex), which generically results in several ambiguities. Furthermore, the geometry ``seen'' by matter is encoded in the spin foam itself and thus dynamical. One approach to investigate the continuum limit of such systems is via renormalizing (e.g. coarse graining) the theory.

In this talk I will present and discuss the before mentioned issues for a simpler 2D toy model, namely an Ising model coupled to a dynamical background. The distance / coupling between Ising spins will be given by the labels of this background. I investigate the phases of this model by a numerical algorithm (tensor network renormalization) and identify regions (in parameter space) in which the two systems are weakly coupled and regions in which they are strongly coupled.

Based on: Phys.Rev. D92 (2015) 064007 / arXiv:1506.04749 [gr-qc]