Interaction of neutrinos with a cosmological k-essence scalar

Gauthier, C.; Saotome, Ryo; Akhoury, Ratindranath

doi:10.1007/jhep07(2010)062

Cited by 3 publications

(5 citation statements)

References 47 publications

(79 reference statements)

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“…For future reference we can also define as z ðnÞ the sum of all components at level n, e.g., See [63] for earlier work on spinors in (nondegenerate) scalar-tensor theories of gravity. Also related to the context of DHOST theories are the analyses of [64,65] who considered the behavior of a minimally coupled spinor under disformal transformations and [66,67] who studied degenerate scalar-spinor systems without gravity.…”

Section: A Majorana Field In Dhostmentioning

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: A Majorana Field In Dhostmentioning

confidence: 99%

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

Deffayet

García-Sáenz

2020

Phys. Rev. D

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“…6 Such a setup was already suggested as a possible origin of small neutrino masses [14]. This 4 Similarly to [9] we could include nonlinear terms like ∂µφ∂ν φ.…”

mentioning

confidence: 95%

“…Similarly to[9] we could include nonlinear terms like ∂µφ∂ν φ. However, these terms would lead to a higher order interaction and correspondingly to a lower strong-coupling scale 5.…”

mentioning

confidence: 99%

Price for environmental neutrino-superluminality

Dvali

Vikman

2012

J. High Energ. Phys.

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Abstract:We ask whether the recent OPERA results on neutrino superluminality could be an environmental effect characteristic of the local neighborhood of our planet, without the need of violation of the Poincaré-invariance at a fundamental level. We show, that model-indepenently, such a possibility implies the existence of new gravitational degrees of freedom. Namely, this explanation requires the existence of a new spin-2 field of a planetary Compton wave-length that is coupled to neutrinos and the rest of the matter asymmetrically, both in the magnitude and in the sign. Sourced by the earth this field creates an effective metric on which neutrinos propagate superluminally, whereas other species are much less sensitive to the background. Such a setup, at an effective field theory level, passes all immediate phenomenological tests, but at the expense of sacrificing calculability for some of the phenomena that are under perturbative control in ordinary gravity. The natural prediction is an inevitable appearance of a testable long-range gravitytype fifth force. Despite phenomenological viability, the sign asymmetry of the coupling we identify as the main potential obstacle for a consistent UV-completion. We also discuss the possible identification of this field with a Kaluza-Klein state of an extra dimension in which neutrino can propagate.

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“…where the mass scale M ψ is the suppression scale for the fermion species ψ. A similar coupling was first considered in [13].…”

Section: Massless Fermions With the Actionmentioning

confidence: 91%

“…A similar coupling was first considered in [13]. Let us focus on a typical situation where the metric is Minkowskian to a good approximation (this is the case on earth where Newton's potential is Φ ⊕ ∼ 10 −9 ) and the scalar field varies on scales much larger than the Compton wave length of the fermions.…”

Section: Pacs Numbersmentioning

confidence: 99%

Lorentz invariance violation in modified gravity

Brax¹

2012

Physics Letters B

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We consider an environmentally dependent violation of Lorentz invariance in scalar-tensor models of modified gravity where General Relativity is retrieved locally thanks to a screening mechanism. We find that fermions have a modified dispersion relation and would go faster than light in an anisotropic and space-dependent way along the scalar field lines of force. Phenomenologically, these models are tightly restricted by the amount of Cerenkov radiation emitted by the superluminal particles, a constraint which is only satisfied by chameleons. Measuring the speed of neutrinos emitted radially from the surface of the earth and observed on the other side of the earth would probe the scalar field profile of modified gravity models in dense environments. We argue that the test of the equivalence principle provided by the Lunar ranging experiment implies that a deviation from the speed of light, for natural values of the coupling scale between the scalar field and fermions, would be below detectable levels, unless gravity is modified by camouflaged chameleons where the field normalisation is environmentally dependent. PACS numbers:The discovery of the acceleration of the Universe has led to a flurry of scenarios involving scalar fields and leading to different types of modified gravity models [1]. All of them allow for large deviations from General Relativity on astrophysical scales while preserving Newton's law locally in the solar system and in laboratories on earth. This is achieved thanks to screening features such as the Vainshtein mechanism for theories with higher order derivative self interactions[2], or the chameleon[3], symmetron [4] or Damour-Polyakov properties [5] for theories with non-linear effective potentials in the presence of pressure-less matter. Recently and after the claim of super-luminal propagation of neutrinos by the OPERA experiment [6], it has been suggested that fermions may travel faster than the speed of light in dense environments where the presence of matter offers a breaking of Lorentz invariance [7]. This was further pursued in [8][9][10] and then in [11] where Galileons were used to describe the OPERA claims although failing to respect the tight bounds on the deviation of the electron speed from the speed of light. In this work, we will describe a general mechanism which leads to anomalously fast fermions and where the breaking of Lorentz invariance by a two-tensor appears naturally in models of modified gravity with screening properties. Chameleon, symmetron and Galileon models can reproduce phenomena of the type indicated by the preliminary OPERA publication. Only models with a thin shell screening mechanism, i.e. chameleons, are compatible with the constraints on the speed of charged leptons. Unfortunately for chameleons, Galileons and symmetrons and for natural values of the coupling between the scalar field and fermions we find that the deviation of the fermion speed from the speed of light would be unobservably small. More generally and model independently, testing the propert...

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Interaction of neutrinos with a cosmological k-essence scalar

Cited by 3 publications

References 47 publications

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

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

Price for environmental neutrino-superluminality

Lorentz invariance violation in modified gravity

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