https://doi.org/10.1140/epjc/s10052-017-4710-3
Regular Article - Theoretical Physics
Characteristics of the new phase in CDT
1
The Niels Bohr Institute, Copenhagen University, Blegdamsvej 17, 2100, Copenhagen Ø, Denmark
2
Institute of Physics, Jagiellonian University, ul. prof. Stanislawa Lojasiewicza 11, 30-348, Kraków, Poland
3
Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands
* e-mail: r.loll@science.ru.nl
Received:
15
January
2017
Accepted:
19
February
2017
Published online:
10
March
2017
The approach of Causal Dynamical Triangulations (CDT), a candidate theory of nonperturbative quantum gravity in 4D, turns out to have a rich phase structure. We investigate the recently discovered bifurcation phase 
and relate some of its characteristics to the presence of singular vertices of very high order. The transition lines separating this phase from the “time-collapsed” B-phase and the de Sitter phase 
are of great interest when searching for physical scaling limits. The work presented here sheds light on the mechanisms behind these transitions. First, we study how the B– transition signal depends on the volume fixing implemented in the simulations, and find results compatible with the previously determined second-order character of the transition. The transition persists in a transfer matrix formulation, where the system’s time extension is taken to be minimal. Second, we relate the new – transition to the appearance of singular vertices, which leads to a direct physical interpretation in terms of a breaking of the homogeneity and isotropy observed in the de Sitter phase when crossing from to the bifurcation phase .
© The Author(s), 2017
