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The European physical journal. C, Particles and fields, 2017, Vol.77 (3), p.152-17, Article 152
Ort / Verlag
Berlin/Heidelberg: Springer Berlin Heidelberg
Erscheinungsjahr
2017
Quelle
Alma/SFX Local Collection
Beschreibungen/Notizen
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
C
b
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
C
d
S
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
–
C
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
C
b
–
C
d
S
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
C
d
S
to the bifurcation phase
C
b
.