http://arxiv.org/abs/1608.07772
The spatially closed Friedmann-Lemaitre-Robertson-Walker model in loop quantum cosmology admits two inequivalent consistent quantizations: one based on expressing field strength in terms of holonomies over closed loops, and, another using a connection operator and open holonomies. Using effective dynamics, we investigate the phenomenological differences between the two quantizations for single fluid and two fluid scenarios with various equations of state, including phantom matter. We show that a striking difference between the two quantizations is the existence of two distinct quantum turnarounds, either bounces or recollapses, in the connection quantization, in contrast to a single distinct quantum bounce or recollapse in the holonomy quantization. These results generalize an earlier result on two distinct quantum bounces for stiff matter by Corichi and Karami. However, we find that in certain situations two distinct quantum turnarounds can become virtually indistinguishable. And depending on initial conditions, a pure quantum cyclic universe can also exist undergoing quantum bounce and a quantum recollapse. We show that for various equations of states, connection based quantization leads to super-Planckian values of the energy density and the expansion scalar at quantum turnarounds. Interestingly, we find that very extreme energy densities can also occur for holonomy quantization, breaching the maximum allowed density in spatially flat loop quantized model. However, the expansion scalar in all these cases is bounded by a universal value.
J. Dupuy and P. Singh
Tue, 30 Aug 16
31/78
Comments: 19 pages, 19 figures
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