The pre-inflationary dynamics of LQC confronting quantum gravity with observations

• The early universe provides an ideal setting to test quantum gravity ideas. The inflationary paradigm provides a telescope to peer into the Planck regime. Furthermore, it has been extremely successful with structure formation. Can one provide a quantum gravity completion of the inflationary paradigm thereby overcoming some of its limitations? In LQG the answer is yes in the following precise sense: • Background geometry: Singularity Resolution and precise quantum geometry for the Planck regime. • Perturbations: Since they propagate on quantum geometry using QFT on cosmological quantum geometries (aa, Lewandowski, Kaminski), trans-Planckian issues can be handled systematically provided the test field approximation holds. Analyzed in detail using the renormalized stress-energy of (1)(2) on the quantum geometry of Ψ. Detailed numerics show that the approximation does hold if φ p1. (Agullo, AA, Nelson) • Extension: If ΦB P1 & ψ is a 'permissible vacuum,' modes of observational interest are all in the Bunch Davis vacuum at the onset of the WMAP slow roll → Predictions of the standard inflationary scenario for the power spectra, spectral indices & ratio of tensor to scalar modes are recovered starting from the deep Planck era. (Agullo, AA, Nelson) • Non-Gaussianity: There is a small window in φB for which at the onset of inflation ψ has excitations over the Bunch-Davis vacuum. These give rise to specific 3-point functions ('bi-spectrum') which are important for the 'halo bias'. Could be observed in principle: Link between observations and the initial state! A window to probe the Planck era around the LQC bounce. (Agullo, AA, Nelson, Shandera, Ganc, Komatsu) • Note: LQG does not imply that inflation must have occurred because it does not address particle physics issues. The analysis simply assumes that there is an inflaton with a suitable potential. But it does show concretely that many of the standard criticisms (e.g. due to Brandenberger) of inflation can be addressed in LQG by facing the Planck regime squarely.