Analysing (cosmological) singularity avoidance in loop quantum gravity using U (1)3 coherent states and Kummer's functions

被引:2
作者
Giesel, Kristina [1 ]
Winnekens, David [1 ]
机构
[1] Friedrich Alexander Univ Erlangen Nurnberg, Inst Quantum Grav Theoret Phys 3, Dept Phys, Staudtstr 7, D-91058 Erlangen, Germany
关键词
(cosmological) singularity avoidance; loop quantum gravity; coherent states; Kummer functions; TRIAD OPERATOR QUANTIZATION; CURVED SPACETIME LIMIT; FIELD-THEORY; CONSISTENCY CHECK; VOLUME; GCS; QGR; QFT; IV;
D O I
10.1088/1361-6382/acc0c7
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
Using a new procedure based on Kummer's Confluent Hypergeometric Functions, we investigate the question of singularity avoidance in loop quantum gravity (LQG) in the context of U(1)(3) complexifier coherent states and compare obtained results with already existing ones. Our analysis focuses on the dynamical operators, denoted by (q) over cap (i0)(I0) (r), whose products are the analogue of the inverse scale factor in LQG and also play a pivotal role for other dynamical operators such as matter Hamiltonians or the Hamiltonian constraint. For graphs of cubic topology and linear powers in (q) over cap (i0)(I0) (r), we obtain the correct classical limit and demonstrate how higher order corrections can be computed with this method. This extends already existing techniques in the way how the involved fractional powers are handled. We also extend already existing formalisms to graphs with higher-valent vertices. For generic graphs and products of (q) over cap (i0)(I0) (r), using estimates becomes inevitable and we investigate upper bounds for these semiclassical expectation values. Compared to existing results, our method allows to keep fractional powers involved in (q) over cap (i0)(I0) (r) throughout the computations, which have been estimated by integer powers elsewhere. Similar to former results, we find a non-zero upper bound for the inverse scale factor at the initial singularity. Additionally, our findings provide some insights into properties and related implications of the results that arise when using estimates and can be used to look for improved estimates.
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页数:72
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