HET journal club by Timothy Budd (NBI) – Niels Bohr Institute - University of Copenhagen

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HET journal club by Timothy Budd (NBI)

Trees and spatial topology change in 2d CDT

I will discuss a paper by Jan Ambjørn and me which should appear on the arXiv this week. In this paper we use bijections between quadrangulations and trees to study two-dimensional quantum gravity. We show that generalized CDT, i.e. Causal Dynamical Triangulations in two space-time dimensions and spatial topology change, can be described by an ensemble of random labeled trees. This description allows us to solve the discrete model analytically and to reproduce known expressions in the continuum limit. Finally, if time permits, I will demonstrate a novel bijection between quadrangulations, which reveals a symmetry of certain transition amplitudes in the continuum.