Hyperbolic field space and swampland conjecture for DBI scalar

Mizuno, Shuntaro; Mukohyama, Shinji; Zhang, Yun-Long

doi:10.1088/1475-7516/2019/09/072

Cited by 40 publications

(33 citation statements)

References 186 publications

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“…However, if the compatibility with the GW170817 is imposed on the Einstein-Gauss-Bonnet theory is imposed, the function ξ(φ) = λ V (φ) does not satisfy in general the differential equation (17), unless the potential has a very specific form, which however does not yield a viable inflationary phenomenology in the context of the present paper [72]. However, if the condition ξ ′ ξ ′′ ≪ 1 is imposed in the theory, then the function ξ(φ) = λ V (φ) satisfies the differential equation the differential equation (47), only if λ = 3/4. In Ref.…”

Section: The Swampland Criteria For the Gw170817-compatible Einstmentioning

confidence: 88%

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Swampland implications of GW170817-compatible Einstein-Gauss-Bonnet gravity

2020

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We revisit the Einstein-Gauss-Bonnet theory in view of the GW170817 event, which compels that the gravitational wave speed is equal to c 2 T = 1 in natural units. We use an alternative approach compared to one previous work of ours, which enables us to express all the slow-roll indices and the observational indices as functions of the scalar field. Using our formalism we investigate if the Swampland criteria are satisfied for the Einstein-Gauss-Bonnet theory and as we demonstrate, the Swampland criteria are satisfied for quite general forms of the potential and the Gauss-Bonnet coupling function ξ(φ), if the slow-roll conditions are assumed to hold true.PACS numbers: 04.50. Kd, 95.36.+x, 98.80.Cq,

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Section: The Swampland Criteria For the Gw170817-compatible Einstmentioning

confidence: 88%

“…In the literature there is currently a lot of activity regarding the implications of the Swampland criteria, see Refs. [40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58][61][62][63][64][65][66][67][68][69][70][71]. Also in Ref.…”

Section: The Swampland Criteria For the Gw170817-compatible Einstmentioning

confidence: 99%

Swampland implications of GW170817-compatible Einstein-Gauss-Bonnet gravity

2020

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“…The resulting velocities can subsequently be used to compute the turning rate analytically. As an example, hyperinflation and its generalizations [9,10,38] (also, section 4.1) are a well-studied class of high-turn rate models with such a Hessian.…”

Section: The Aligned Hessian Approximationmentioning

confidence: 99%

“…Hyperinflation [9,10,38] is a rapidly turning solution possible whenever the field space is hyperbolic, and the potential sufficiently steep around the origin. As previously noted by [23], it is a special case of sidetracked inflation [13,14].…”

Section: Hyperinflationmentioning

confidence: 99%

The multi-field, rapid-turn inflationary solution

Aragam

Paban

Rosati

2021

J. High Energ. Phys.

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There are well-known criteria on the potential and field-space geometry for determining if slow-roll, slow-turn, multi-field inflation is possible. However, even though it has been a topic of much recent interest, slow-roll, rapid-turn inflation only has such criteria in the restriction to two fields. In this work, we generalize the two-field, rapid-turn inflationary attractor to an arbitrary number of fields. We quantify a limit, which we dub extreme turning, in which rapid-turn solutions may be found efficiently and develop methods to do so. In particular, simple results arise when the covariant Hessian of the potential has an eigenvector in close alignment with the gradient — a situation we find to be common and we prove generic in two-field hyperbolic geometries. We verify our methods on several known rapid-turn models and search two type-IIA constructions for rapid-turn trajectories. For the first time, we are able to efficiently search for these solutions and even exclude slow-roll, rapid-turn inflation from one potential.

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“…Multi-field models display rich dynamics and phenomenology, and have been extensively studied in the last 20 years. They introduce several new features: the (possible) generation of isocurvature (or entropic) perturbations and subsequently the superhorizon evolution of the curvature perturbation; the possibility for the power spectrum's enhancement that can lead to large non-Gaussianities [91][92][93][94][95] and primordial black holes formation [96,97]; and the evasion of swampland conjectures [98][99][100][101][102][103], to list a few. Before exploring these endless possibilities one has to understand the underlying dynamics and the unique features of multi-field inflation.…”

Section: Motivation For Multiple Fieldsmentioning

confidence: 99%

Dynamics and observational signatures from multi-field inflation

Christodoulidis

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This chapter offers a non-technical introduction to modern cosmology with emphasis on the cosmological milestones of the last century. We also provide an outline of the thesis and set the notation. Expansion of the Universe Expansion of the UniverseAround 1920, a "Great Debate" took place amongst astronomers regarding the size of the universe [12]. On one side, astronomers such as H. Shapley argued for a small universe of the size of the Milky Way, while the opposing side represented by H. Curtis claimed that distant nebulae were distinct galaxies located at large distances from Earth. The debate was finally settled by E. Hubble in 1927 [13]. Analysing data from stars with variable luminosity, known as Cepheid stars, of what appeared to be distant nebula enabled him to perform a cosmic distance calibration, that is a way to measure distances of distant objects. Those objects were shown to lie outside of our galaxy and therefore settled the Great Debate. Combining the previous results with redshift measurements of various galaxies led to his famous law relating distance to velocity. This relation had already been proposed by G. Lemaître as a solution of an expanding universe. Distant galaxies appeared to recede from us with a velocity proportional to their distance which implied that the universe is expanding.A few decades later, A. Penzias and R. Wilson accidentally discovered a mysterious radiation in the microwave part of the spectrum that was coming from every part of the sky. The existence of this radiation was already predicted by G. Gamow in 1948 as the afterglow of the Big Bang and for this reason it became known as the cosmic microwave background (CMB) radiation [14]. Being one of the key predictions of the expanding universe, the Big Bang scenario was established in the cosmological community. Up to the end of the 20 th century, the dominant view included a cold universe whose average density of matter would determine its fate; a densely enough universe would recollapse in the future leading to the "Big Crunch", whereas if its density was lower than a critical value it would expand forever, leading to the "Big Chill". In any case, the expansion of the universe would decelerate because it would be subject only to gravitational forces of attractive nature.The situation changed in 1998 due to the first direct evidence for cosmic acceleration. S. Perlmutter, from the Supernova Cosmology Project, and B. P. Schmidt and A. G. Riess, from the High-Z Supernova Search Team, analysed data from supernovae type Ia that enabled them to measure distances in the universe, in a similar fashion to what E. Hubble had done in the past [15,16]. These observations indicated that universe's expansion is accelerating and, hence, the universe should be filled with an unknown form of energy dubbed dark energy. In the simplest scenario, dark energy is represented by a cosmological constant and is associated with the energy of • Greek letters (µ, ν, • • • ) denote spacetime indices and Latin letters (a, b, • • • ) field-metric indi...

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Hyperbolic field space and swampland conjecture for DBI scalar

Cited by 40 publications

References 186 publications

Swampland implications of GW170817-compatible Einstein-Gauss-Bonnet gravity

Swampland implications of GW170817-compatible Einstein-Gauss-Bonnet gravity

The multi-field, rapid-turn inflationary solution

Dynamics and observational signatures from multi-field inflation

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