Modified Lyth bound and implications of BICEP2 results

Gao, Qing; Gong, Yungui; Li, Tianjun

doi:10.1103/physrevd.91.063509

Cited by 26 publications

(23 citation statements)

References 117 publications

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“…In the last equality, we write out M pl explicitly. Therefore, similar to the Lyth bound [51,52], there is a lower bound on the field excursion for the tachyon,…”

Section: Field Excursionmentioning

confidence: 71%

The reconstruction of tachyon inflationary potentials

Qin

Gong

Lin

et al. 2017

J. Cosmol. Astropart. Phys.

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Abstract. We derive a lower bound on the field excursion for the tachyon inflation, which is determined by the amplitude of the scalar perturbation and the number of e-folds before the end of inflation. Using the relation between the observables like n s and r with the slow-roll parameters, we reconstruct three classes of tachyon potentials. The model parameters are determined from the observations before the potentials are reconstructed, and the observations prefer the concave potential. We also discuss the constraints from the reheating phase preceding the radiation domination for the three classes of models by assuming the equation of state parameter w re during reheating is a constant. Depending on the model parameters and the value of w re , the constraints on N re and T re are different. As n s increases, the allowed reheating epoch becomes longer for w re = −1/3, 0 and 1/6 while the allowed reheating epoch becomes shorter for w re = 2/3.

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“…In the last equality, we write out M pl explicitly. Therefore, similar to the Lyth bound [51,52], there is a lower bound on the field excursion for the tachyon,…”

Section: Field Excursionmentioning

confidence: 71%

The reconstruction of tachyon inflationary potentials

Qin

Gong

Lin

et al. 2017

J. Cosmol. Astropart. Phys.

Self Cite

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“…where the first three coefficients λ 1 , λ 2 and λ 3 are determined from n s , r and n s = dn s /d ln k, the coefficients λ 4 and λ 5 are determined from the near-inflection condition V φ ≈ 0 and V φφ ≈ 0 1 . The polynomial potential may be obtained from supergravity model building [63]. Choosing φ * = −0.54 and φ infl = 0.0367, and using the Planck 2015 results, k * = 0.05Mpc −1 , n s = 0.9686, r = 0.005, n s = −0.0008 and P ζ = 2.2 × 10 −9 [62], we get λ 1 = −0.0353553, λ 2 = −0.0115783, λ 3 = −0.00235702, λ 4 = 728.239, λ 5 = −11882.9 and V 0 = 1.55×10 −10 .…”

Section: Primordial Black Holes From Inflationmentioning

confidence: 99%

Primordial black holes and second order gravitational waves from ultra-slow-roll inflation

Gong

2018

J. Cosmol. Astropart. Phys.

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172

120

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The next generation of space-borne gravitational wave detectors may detect gravitational waves from extreme mass-ratio inspirals with primordial black holes. To produce primordial black holes which contribute a non-negligible abundance of dark matter and are consistent with the observations, a large enhancement in the primordial curvature power spectrum is needed. For a single field slow-roll inflation, the enhancement requires a very flat potential for the inflaton, and this will increase the number of e-folds. To avoid the problem, an ultra-slow-roll inflation at the near inflection point is required. We elaborate the conditions to successfully produce primordial black hole dark matter from single field inflation and propose a toy model with polynomial potential to realize the big enhancement of the curvature power spectrum at small scales while maintaining the consistency with the observations at large scales. The power spectrum for the second order gravitational waves generated by the large density perturbations at small scales is consistent with the current pulsar timing array observations.

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“…This quantity is known as Lyth Bound and represents an estimation of ∆φ at horizon crossing: ∆φ H.c. . In the last years, different studies concerning the variation of the field and the Lyth bound itself have been done [5][6][7]. In future, foreseen CMB polarization missions ( [8][9][10][11][12]) and gravitational waves experiments ( [13]) will constrain cosmological observables better than the current available data, [14,15].…”

Section: Introductionmentioning

confidence: 99%

Lyth bound, eternal inflation, and future cosmological missions

Marco

2017

Phys. Rev. D

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In this paper we provide a new expression for the variation of the inflaton field ∆φ during the horizon crossing epoch in the context of single field slow roll inflationary models. Such an expression represents a generalization of the well-know Lyth bound. We also explore the consequences of a detection of permille order of the tensor-to-scalar ratio amplitude, r, as well as an improvement on the estimation of the scalar spectral index, ns and its running αs, by the upcoming cosmic macrowave background (CMB) polarization experiments that will provide plausible constraints on the quantity ∆φ during the horizon exit moment. In addition we discuss the relation between the local variation of the field and the possibilities of an eternal inflation. The results of the analysis are completely model independent.

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Modified Lyth bound and implications of BICEP2 results

Cited by 26 publications

References 117 publications

The reconstruction of tachyon inflationary potentials

The reconstruction of tachyon inflationary potentials

Primordial black holes and second order gravitational waves from ultra-slow-roll inflation

Lyth bound, eternal inflation, and future cosmological missions

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