Preinflationary genesis with CMB B-mode polarization

Liu, Zhiguo; Li, Hong; Piao, Yun-Song

doi:10.1103/physrevd.90.083521

Cited by 43 publications

(42 citation statements)

References 81 publications

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“…In Refs. [29], [30], the preinflationary universe is in a slowly expanding genesis phase with ǫ ≪ −1, which is almost Minkowski space. This genesis phase actually also belongs to the superinflation, but since ǫ ≪ −1, the expansion is actually slow; see also [28] for the emergent universe.…”

Section: A the Superinflationary Phase Before Inflationmentioning

confidence: 99%

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Preinflationary primordial perturbations

2015

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The large-scale power deficit in the cosmic microwave background fluctuations might be relevant with the physics of pre-inflation, a bounce, or a superinflationary phase preceding slow-roll inflation, which can provide a singular-free realization of inflation. We investigate the primordial perturbations from such pre-inflationary evolutions, which generally may consist of multiple phases with different background dynamics, and give a universal formula for the power spectrum of primordial perturbations in terms of the recursive Bogoliubov coefficients. We also apply our formula to corresponding cases and show how the intensity of large-scale power suppression is affected by the pre-inflationary physics.

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Section: A the Superinflationary Phase Before Inflationmentioning

confidence: 99%

“…The superinflationary phase before slow-roll inflation may also provide a singular-free realization of inflation, which in the meantime explains the anomalies of the CMB power spectrum [18], [28]; see also [29], [30] for an almost flat pre-inflationary universe.…”

Section: Introductionmentioning

confidence: 99%

Preinflationary primordial perturbations

2015

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“…However, the inflation still suffers from the cosmological singularity problem [1,2], unless it was preceded by a bounce [3][4][5][6][7] or a Genesis phase [8][9][10]. It is exciting to study classical nonsingular cosmology, such as bounce universe models [11,12], Genesis models [13][14][15], slow expansion models [16][17][18][19], since we might get classical nonsingular cosmology without begging the details of the unknown UV-complete gravity theory.…”

Section: Introductionmentioning

confidence: 99%

The Effective Field Theory of nonsingular cosmology

Cai

Wan

et al. 2017

J. High Energ. Phys.

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149

150

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In this paper, we explore the nonsingular cosmology within the framework of the Effective Field Theory (EFT) of cosmological perturbations. Due to the recently proved no-go theorem, any nonsingular cosmological models based on the cubic Galileon suffer from pathologies. We show how the EFT could help us clarify the origin of the no-go theorem, and offer us solutions to break the no-go. Particularly, we point out that the gradient instability can be removed by using some spatial derivative operators in EFT. Based on the EFT description, we obtain a realistic healthy nonsingular cosmological model, and show the perturbation spectrum can be consistent with the observations.

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“…With positive n t , the contribution to C TT ℓ (ℓ < 50) is less than red tensor spectrum, making the model prediction more consistent with the data [12]. It has been shown that once n t is released to be a free parameter in the likelihood analysis, a positive n t is found to be at 3σ confidence level (CL) [10,13].…”

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confidence: 84%

Precision of future experiments measuring primordial tensor fluctuation

Wang

2014

Sci. China Phys. Mech. Astron.

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Recently the second phase of Background Imaging of Cosmic Extragalactic Polarization (BICEP2) claimed a detection of the tensor-to-scalar ratio (r) of primordial fluctuation at 5σ confidence level. If it is true, this large and measurable amplitude (r ≃ 0.2) of B-mode polarization indicates that it is possible to measure the shape of CMB B-mode polarization with future experiments. We forecast the precision of r and the tensor spectral index nt measurements, with nt as a free parameter, from a Planck-like experiment, and from Spider and POLARBEAR given the current understanding of their experimental noise and foreground contamination. We quantitatively determine the signalto-noise of the measurement in r-nt parameter space for the three experiments. The forecasted signal-to-noise ratio of the B-mode polarization somewhat depends on nt, but strongly depends on the true value of r. . This detection, if confirmed by ongoing and forthcoming experiments, implies a large amplitude of primordial tensor fluctuations and therefore has profound theoretical implications. For instance, given the current detected amplitude r = 0.2, the inflationary potential and the associated derivatives can be completely reconstructed around a few number of e-folds [3]. However, on the other hand, several other groups claimed recently that the BICEP2 results may come from the spurious signal of the polarized dust [2].Assuming the BICEP2 result is correct and therefore the primordial tensor fluctuation is measurable, it is possible to measure not only the amplitude but also the shape of the primordial tensor power spectrum with future experiment. The BICEP2 measured B-mode power spectrum has power excess at small scales, indicating a blue tilt (n t ) of the spectrum [26]. The statistical significance of such a blue tensor spectrum is found to be in between 1σ and 2σ [7,8].The hint of blue n t becomes stronger when the BICEP2 data is combined with Wilkinson Microwave Anisotropy Probe (WMAP ) and Planck data [8][9][10]. In fact, before the tensor mode is detected, the theoretical prediction of temperature power spectrum is around 5%-10% higher than the measurement on ℓ < 50 [11]. The detected tensor-to-scalar ratio r = 0.2 will further enhance the low-ℓ temperature power spectrum (C

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Preinflationary genesis with CMB B-mode polarization

Cited by 43 publications

References 81 publications

Preinflationary primordial perturbations

Preinflationary primordial perturbations

The Effective Field Theory of nonsingular cosmology

Precision of future experiments measuring primordial tensor fluctuation

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