The Lyth bound revisited

Efstathiou, G.; Mack, Katherine J.

doi:10.1088/1475-7516/2005/05/008

Cited by 63 publications

(90 citation statements)

References 33 publications

(74 reference statements)

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“…In particular, in the context of inflation [2][3][4][5], an observation of a tensor-to-scalar ratio r 10 −2 implies an unprecedented connection between empirical observations and quantum gravity, for two reasons: it provides a measurement of the quantum mechanical variance of the tensor modes of the metric [6][7][8][9][10][11][12][13], and it indicates a super-Planckian field excursion [14,15]. An impressive variety of observational efforts are approaching the sensitivity required to detect r in this range [16], with a recent report of a detection of B-mode polarization [17,18] that may contain a signal of primordial origin corresponding to inflationary tensor modes [19,20], depending on the outcome of important foreground measurements generalizing [21,22].…”

Section: Motivation and Overviewmentioning

confidence: 99%

“…This is the case for the simplest generalization of (3.10) in section 3.1 to Riemann surfaces, with the three-form fluxes threading cycles consisting of products of a-cycles or products of b-cycles, as in (3.3). Then we will have two cases of interest, 15 The q 2 1 term need not be completely subdominant (the regime studied for simplicity in [73]). It would consistent to let the q 2 1 term be large enough that it combined with the n 2 3 terms stabilizes V, leading to a positive term scaling like σ −8/3 which combines with the second and third terms in (4.4) to stabilize σ.…”

Section: Jhep09(2014)123mentioning

confidence: 99%

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The powers of monodromy

McAllister

Silverstein

Westphal

et al. 2014

J. High Energ. Phys.

237

339

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Flux couplings to string theory axions yield super-Planckian field ranges along which the axion potential energy grows. At the same time, other aspects of the physics remain essentially unchanged along these large displacements, respecting a discrete shift symmetry with a sub-Planckian period. After a general overview of this monodromy effect and its application to large-field inflation, we present new classes of specific models of monodromy inflation, with monomial potentials µ 4−p φ p . A key simplification in these models is that the inflaton potential energy plays a leading role in moduli stabilization during inflation. The resulting inflaton-dependent shifts in the moduli fields lead to an effective flattening of the inflaton potential, i.e. a reduction of the exponent from a fiducial value p 0 to p < p 0 . We focus on examples arising in compactifications of type IIB string theory on products of tori or Riemann surfaces, where the inflaton descends from the NS-NS two-form potential B 2 , with monodromy induced by a coupling to the R-R field strength F 1 . In this setting we exhibit models with p = 2/3, 4/3, 2, and 3, corresponding to predictions for the tensor-to-scalar ratio of r ≈ 0.04, 0.09, 0.13, and 0.2, respectively. Using mirror symmetry, we also motivate a second class of examples with the role of the axions played by the real parts of complex structure moduli, with fluxes inducing monodromy.

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Section: Motivation and Overviewmentioning

confidence: 99%

Section: Jhep09(2014)123mentioning

confidence: 99%

The powers of monodromy

McAllister

Silverstein

Westphal

et al. 2014

J. High Energ. Phys.

237

339

View full text Add to dashboard Cite

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“…The central challenge and opportunity is this: any such derivation depends crucially on the assumptions made about the ultraviolet completion of gravity. String theory is by far the best-understood example of a theory of quantum gravity, but the considerations described below are more general and rely only on the firmly-established Wilsonian approach to effective field theory, which allows systematic incorporation of the 26 More recently, a Monte Carlo study of single-field slow-roll inflationary models which match recent data on n s and its first derivative revealed an even stronger bound j^ > 10 x (g^) [84]. 27 A futuristic direct-detection gravitational wave experiment like the Big Bang Observer (BBO) might someday complement the observations of CMB polarization [85][86][87][88].…”

Section: Sensitivity To Symmetries and To Fundamental Physicsmentioning

confidence: 99%

Probing Inflation with CMB Polarization

Adshead

Amblard

Ashoorioon

et al. 2009

AIP Conference Proceedings

298

310

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We summarize the utility of precise cosmic microwave background (CMB) polarization measurements as probes of the physics of inflation. We focus on the prospects for using CMB measurements to differentiate various inflationary mechanisms. In particular, a de tection of primordial B-mode polarization would demonstrate that inflation occurred at a very high energy scale, and that the inflaton traversed a super-Planckian distance in field space. We explain how such a detection or constraint would illuminate aspects of physics at the Planck scale. Moreover, CMB measurements can constrain the scale-dependence and non-Gaussianity of the primordial fluctuations and limit the possibility of a significant isocurvature contribution. Each such limit provides crucial information on the underlying inflationary dynamics. Finally, we quantify these considerations by presenting forecasts for the sensitivities of a future satellite experiment to the inflationary parameters. 10Reuse of AIP Publishing content is subject to the terms at: https://publishing.aip. Striking advances in observational cosmology over the past two decades have provided us with a consistent account of the form and composition of the universe. Now that key cosmological parameters have been determined to within a few percent, we anticipate a generation of experiments that move beyond adding precision to measurements of what the universe is made of, but instead help us learn why the universe has the form we observe. In particular, during the coming decade, observational cosmology will probe the detailed dynamics of the universe in the earliest instants after the Big Bang, and start to yield clues about the physical laws that governed that epoch. Future experiments will plausibly reveal the dynamics responsible both for the large-scale homogeneity and flatness of the universe, and for the primordial seeds of small-scale inhomogeneities, including our own galaxy.The leading theoretical paradigm for the initial moments of the Big Bang is inflation [1][2][3][4][5][6], a period of rapid accelerated expansion. Inflation sets the initial conditions for conventional Big Bang cosmology by driving the universe towards a homogeneous and spatially flat configuration, which accurately describes the average state of the universe. At the same time, quantum fluctuations in both matter fields and spacetime produce minute inhomogeneities [7][8][9][10][11][12]. The seeds that grow into the galaxies, clusters of galaxies and the temperature anisotropies in the cosmic microwave background (CMB) are thus planted during the first moments of the universe's existence. By measuring the anisotropies in the microwave background and the large scale distribution of galaxies in the sky, we can infer the spectrum of the primordial perturbations laid down during inflation, and thus probe the underlying physics of this era. Any successful inflationary model will deliver a universe that is, on average, spatially flat and homogeneous -and one homogeneous universe looks very much like ano...

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“…5 Efstathiou and Mack [34] use a stochastic approach to extend the Lyth Bound over the entire inflationary period. For models satisfying the spectral index constraint 0.92 < n < 1.06, they obtain the bound ∆φ…”

Section: The Last E-foldmentioning

confidence: 99%

The Lyth Bound and the end of inflation

Easther

Kinney

Powell

2006

J. Cosmol. Astropart. Phys.

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We derive an extended version of the well-known Lyth Bound on the total variation of the inflaton field, incorporating higher order corrections in slow roll. We connect the field variation ∆φ to both the spectral index of scalar perturbations and the amplitude of tensor modes. We then investigate the implications of this bound for "small field" potentials, where the field rolls off a local maximum of the potential. The total field variation during inflation is generically of order m Pl , even for potentials with a suppressed tensor/scalar ratio. Much of the total field excursion arises in the last e-fold of inflation and in single field models this problem can only be avoided via fine-tuning or the imposition of a symmetry. Finally, we discuss the implications of this result for inflationary model building in string theory and supergravity.

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The Lyth bound revisited

Cited by 63 publications

References 33 publications

The powers of monodromy

The powers of monodromy

Probing Inflation with CMB Polarization

The Lyth Bound and the end of inflation

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