May 6 – 10, 2024
US/Eastern timezone

Angular power spectrum from different regularizations in LQC

May 7, 2024, 3:15 PM
15m
FAU FTL Room 312

FAU FTL Room 312

Cosmology, Black Holes, and other applications/phenomenology Cosmology

Speaker

meysam motaharfar (Louisiana State University)

Description

In Loop Quantum Cosmology (LQC), as in any other quantum theory, various regularizations of the Hamiltonian constraint and quantum ambiguities yield distinct physical implications. Specifically, the treatments of the Euclidean and Lorentzian parts of the Hamiltonian constraint for spatially flat, homogeneous, and isotropic spacetime before quantization results in alternative quantizations of the LQC model—namely, standard LQC, modified LQC-I (mLQC-I), and modified LQC-II (mLQC-II). These models exhibit different background dynamics and pre-inflationary phases, wherein the effects of each regularization might be captured, leading to modifications in the primordial power spectrum and the corresponding angular power. To this end, we compare the primordial power spectrum in the infrared regime for all three different models, tuning the inflaton’s mass and the initial value of the scalar field in such a way that all models predict almost the same number of e-foldings, and the same scale-invariant regime, with the relative difference in power being less than one percent in the scale invariant regime. Our findings reveal that the shape and amplitude of the primordial power spectrum in infra-red regime depend on the chosen regularizations,
quantum ambiguities, the order of adiabatic initial states, and how far they are imposed in the contracting branch. Upon computing the corresponding angular power spectrum for each model, we observed a larger amplitude in large angle, i.e., low l multipoles, for all models, with mLQC-I demonstrating the highest consistency with observations, employing a hybrid approach.

Authors

meysam motaharfar (Louisiana State University) Parampreet Singh (Louisiana State University) Bao-Fei Li (Zhejiang’s University) Parampreet Singh (LSU)

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