TY  - JOUR
AU  - Delhom, A.
AU  - Olmo, G. J.
AU  - Singh, P.
PY  - 2023
DA  - 2023//
TI  - A diffeomorphism invariant family of metric-affine actions for loop cosmologies
T2  - J. Cosmol. Astropart. Phys.
JO  - Journal of Cosmology and Astroparticle Physics
SP  - 059
EP  - 21pp
VL  - 06
IS  - 6
PB  - IOP Publishing Ltd
KW  - quantum cosmology
KW  - modified gravity
KW  - cosmic singularity
AB  - In loop quantum cosmology (LQC) the big bang singularity is generically resolved by a big bounce. This feature holds even when modified quantization prescriptions of the Hamiltonian constraint are used such as in mLQC-I and mLQC-II. While the later describes an effective description qualitatively similar to that of standard LQC, the former describes an asymmetric evolution with an emergent Planckian de-Sitter pre-bounce phase even in the absence of a potential. We consider the potential relation of these canonically quantized non-singular models with effective actions based on a geometric description. We find a 3-parameter family of metric-affine f (R) theories which accurately approximate the effective dynamics of LQC and mLQC-II in all regimes and mLQC-I in the post-bounce phase. Two of the parameters are fixed by enforcing equivalence at the bounce, and the background evolution of the relevant observables can be fitted with only one free parameter. It is seen that the non-perturbative effects of these loop cosmologies are universally encoded by a logarithmic correction that only depends on the bounce curvature of the model. In addition, we find that the best fit value of the free parameter can be very approximately written in terms of fundamental parameters of the underlying quantum description for the three models. The values of the best fits can be written in terms of the bounce density in a simple manner, and the values for each model are related to one another by a proportionality relation involving only the Barbero-Immirzi parameter.
SN  - 1475-7516
UR  - https://arxiv.org/abs/2302.04285
UR  - https://doi.org/10.1088/1475-7516/2023/06/059
DO  - 10.1088/1475-7516/2023/06/059
LA  - English
N1  - WOS:001025410500003
ID  - Delhom_etal2023
ER  -