Inflation from fermions with curvature-dependent mass

Benisty, David; Guendelman, Eduardo; Saridakis, Emmanuel N.; Stoecker, Horst; Struckmeier, Jürgen; Vasak, David

doi:10.1103/physrevd.100.043523

Cited by 26 publications

(17 citation statements)

References 61 publications

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“…Even though this observation is somewhat trivial, it does lead to the perhaps unappreciated possibility of having a very large class of higher-derivative operators within modified gravity without introducing extra pathological DOF classically. We already mentioned, as an example, that the curvature-dependent spinor "mass" terms of the form R nλ λ (some of which have been considered recently in [78,79]) can be seen to be harmless from the point of view of the DOF counting. There is, however, a nontrivial aspect in our result, namely that the coupling to the spinor matter field does not modify the form of the DHOST constraint.…”

Section: Discussionmentioning

confidence: 99%

Degeneracy, matter coupling, and disformal transformations in scalar-tensor theories

Deffayet

García-Sáenz

2020

Phys. Rev. D

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Degenerate scalar-tensor theories of gravity extend general relativity by a single degree of freedom, despite their equations of motion being higher than second order. In some cases, this is a mere consequence of a disformal field redefinition carried out in a nondegenerate theory. More generally, this is made possible by the existence of an additional constraint that removes the would-be ghost. It has been noted that this constraint can be thwarted when the coupling to matter involves time derivatives of the metric, which results in a modification of the canonical momenta of the gravitational sector. In this paper we expand on this issue by analyzing the precise ways in which the extra degree of freedom may reappear upon minimal coupling to matter. Specifically, we study examples of matter sectors that lead either to a direct loss of the special constraint or to a failure to generate a pair of secondary constraints. We also discuss the recurrence of the extra degree of freedom using the language of disformal transformations in particular for what concerns "veiled" gravity. On the positive side, we show that the minimal coupling of spinor fields is healthy and does not spoil the additional constraint. We argue that this virtue of spinor fields to preserve the number of degrees of freedom in the presence of higher derivatives is actually very general and can be seen from the level decomposition of Grassmann-valued classical variables.

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Section: Discussionmentioning

confidence: 99%

Degeneracy, matter coupling, and disformal transformations in scalar-tensor theories

Deffayet

García-Sáenz

2020

Phys. Rev. D

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“…While the standard approach is to introduce some potential with slow-roll behavior, a successful model of quintessential inflation can be obtained from the ansatz of the slow-roll parameter as a function of the scale parameter itself (or the number of e-folds) [77][78][79], especially, with a Lorentzian ansatz [1]. Here we calculate the complete evolution of the universe from this ansatz.…”

Section: Introductionmentioning

confidence: 99%

Quintessential inflation from Lorentzian slow roll

Benisty

Guendelman

2020

Eur. Phys. J. C

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From the assumption that the slow-roll parameter ε has a Lorentzian form as a function of the e-fold number N , a successful model of a quintessential inflation is obtained, as succinctly studied in [1]. The form corresponds to the vacuum energy both in the inflationary and in the dark-energy epochs and satisfies the condition to climb from small values of ε to 1 at the end of the inflationary epoch. We find the corresponding scalar quintessential inflationary potential with two flat regions. Moreover, a reheating mechanism is suggested with numerical estimation for the homogeneous evolution of the universe. The suggested mechanism is consistent with the BBN bound.

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“…While the standard approach is to introduce some potential with slow roll behavior, a successful model of quintessential inflation can be obtained from the ansatz of the slow roll parameter on as a function of the scale parameter itself (or the number of e-folds) [72][73][74], especially, with a Lorentzian ansatz [1]. Here we calculate the complete evolution of the universe from this ansatz.…”

Section: Introductionmentioning

confidence: 99%

Quintessential Inflation from Lorentzian Slow Roll

Benisty,

Guendelman

2020

Preprint

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From the assumption that the slow roll parameter ε has a Lorentzian form as a function of the e-folds number N, a successful model of a quintessential inflation is obtained, as succinctly studied in [1]. The form corresponds to the vacuum energy both in the inflationary and in the dark energy epochs and satisfies the condition to climb from small values of ε to 1 at the end of the inflationary epoch. We find the corresponding scalar Quintessential Inflationary potential with two flat regions. Moreover, a reheating mechanism is suggested with numerical estimation for the homogeneous evolution of the universe. The suggested mechanism is consistent with the BBN bound.

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Inflation from fermions with curvature-dependent mass

Cited by 26 publications

References 61 publications

Degeneracy, matter coupling, and disformal transformations in scalar-tensor theories

Degeneracy, matter coupling, and disformal transformations in scalar-tensor theories

Quintessential inflation from Lorentzian slow roll

Quintessential Inflation from Lorentzian Slow Roll

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