I'm hoping that David Horgan will create some supplemental material for this, as he has for several other LQG and CDT papers. The pedagogical supplements help one read and understand the papers. In any case, here's the recent deHaro paper AND the previous one that lays out the LQC matter bounce idea.(adsbygoogle = window.adsbygoogle || []).push({});

http://arxiv.org/abs/1403.6396

Viability of the matter bounce scenario in Loop Quantum Cosmology from BICEP2 last data

Jaume de Haro, Jaume Amorós

(Submitted on 25 Mar 2014)

The CMB map provided by the Planck project constrains the value of the ratio of tensor-to-scalar perturbations, namely r, to be smaller than 0.11 (95% CL). This bound rules out the simplest models of inflation. However, recent data from BICEP2 is in strong tension with this constrain, as it finds a value r=0.20^{+0.07}_{−0.05}with r=0 disfavored at 7.0σ, which allows these simplest inflationary models to survive. The remarkable fact is that, even though the BICEP2 experiment was conceived to search for evidence of inflation,its experimental data matches correctly theoretical results coming from the matter bounce scenario (the alternative model to the inflationary paradigm). More precisely, most bouncing cosmologies do not pass Planck's constrains due to the smallness of the value of the tensor/scalar ratio r≤0.11,but with new BICEP2 data some of them fit wellwith experimental data. This is the case with the matter bounce scenario in the teleparallel version of Loop Quantum Cosmology.

4 pages, 1 figure

Jaume is the CATALAN form of the name which would be "Jaime" in Spanish. Catalan is a separate language from Spanish which is spoken in Catalonia (the region around Barcelona). The previous paper, on which this one is based is:

http://arxiv.org/abs/1309.0352

Cosmological perturbations in teleparallel Loop Quantum Cosmology

Jaime Haro

(Submitted on 2 Sep 2013 (v1), last revised 18 Nov 2013 (this version, v3))

Cosmological perturbations in Loop Quantum Cosmology (LQC) are usually studied incorporating either holonomy corrections, where the Ashtekar connection is replaced by a suitable sinus function in order to have a well-defined quantum analogue, or inverse-volume corrections coming from the eigenvalues of the inverse-volume operator.

In this paper we will develop an alternative approach to calculate cosmological perturbations in LQC based on the fact that, holonomy corrected LQC in the flat Friedmann-Lemaître-Robertson-Walker (FLRW) geometry could be also obtained as a particular case of teleparallel F(T) gravity (teleparallel LQC). The main idea of our approach is to mix the simple bounce provided by holonomy corrections in LQC with the non-singular perturbation equations given by F(T) gravity, in orderto obtain a matter bounce scenario as a viable alternative to slow-roll inflation.

In our study, we have obtained an scale invariant power spectrum of cosmological perturbations. However, the ratio of tensor to scalar perturbations is of order 1, which does not agree with the current observations. For this reason, we suggest a model where a transition from the matter domination to a quasi de Sitter phase is produced in order to enhance the scalar power spectrum.

http://inspirehep.net/record/1252057?ln=en

4pages, published in JCAP 1311 (November 2013)

David Horgan's other stuff (commentary helpful to reading other QG research papers) is here:

http://quantumtetrahedron.wordpress...or-lqg-by-alesci-assanioussi-and-lewandowski/

(this is what he has for the recent Alesci, Assanioussi, Lewandowski paper on LQG curvature operator)

**Physics Forums | Science Articles, Homework Help, Discussion**

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Viability after BICEP2 of LQC matter bounce

Loading...

**Physics Forums | Science Articles, Homework Help, Discussion**