The variation of the fine-structure constant from disformal couplings

Bruck, Carsten van de; Mifsud, Jurgen; Nunes, Nelson J.

doi:10.1088/1475-7516/2015/12/018

Cited by 34 publications

(39 citation statements)

References 130 publications

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“…Following Ref. [38,59,61,62], we repackage the dark sector of our model by now defining an effective dark energy fluid, ρ DE,eff , with effective equation of state, w eff (z), such that:…”

Section: Theoretical Model: Action and Equations Of Motionmentioning

confidence: 99%

Testing coupled dark energy models with their cosmological background evolution

2017

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We consider a cosmology in which dark matter and a quintessence scalar field responsible for the acceleration of the Universe are allowed to interact. Allowing for both conformal and disformal couplings, we perform a global analysis of the constraints on our model using Hubble parameter measurements, baryon acoustic oscillation distance measurements, and a Supernovae Type Ia data set. We find that the additional disformal coupling relaxes the conformal coupling constraints. Moreover, we show that, at the background level, a disformal interaction within the dark sector is preferred to both ΛCDM and uncoupled quintessence, hence favoring interacting dark energy.

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“…Following Ref. [38,59,61,62], we repackage the dark sector of our model by now defining an effective dark energy fluid, ρ DE,eff , with effective equation of state, w eff (z), such that:…”

Section: Theoretical Model: Action and Equations Of Motionmentioning

confidence: 99%

Testing coupled dark energy models with their cosmological background evolution

2017

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“…Experimental and observational constraints on disformal coupling to particular matter sectors have also been investigated. Disformal couplings to baryons and photons have been severely constrained in terms of the nondetection of new physics in collider experiments [75,[92][93][94][95][96], the absence of spectral distortion of the cosmic microwave background and the violation of distance reciprocal relations [94,[97][98][99], respectively. On the other hand, disformal coupling to the dark sector has been proposed in [84,100] and is presently less constrained in comparison with coupling to visible matter sectors.…”

Section: B Disformal Couplingmentioning

confidence: 99%

Relativistic stars in scalar-tensor theories with disformal coupling

Minamitsuji

Silva

2016

Phys. Rev. D

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We present a general formulation to analyze the structure of slowly rotating relativistic stars in a broad class of scalar-tensor theories with disformal coupling to matter. Our approach includes theories with generalized kinetic terms, generic scalar field potentials and contains theories with conformal coupling as particular limits. In order to investigate how the disformal coupling affects the structure of relativistic stars, we propose a minimal model of a massless scalar-tensor theory and investigate in detail how the disformal coupling affects the spontaneous scalarization of slowly rotating neutron stars. We show that for negative values of the disformal coupling parameter between scalar field and matter, scalarization can be suppressed, while for large positive values of the disformal coupling parameter stellar models cannot be obtained. This allows us to put a mild upper bound on this parameter. We also show that these properties can be qualitatively understood by linearizing the scalar field equation of motion in the background of a general relativistic incompressible star. To address the intrinsic degeneracy between uncertainties in the equation of state of neutron stars and gravitational theory, we also show the existence of universal equation of state independent relations between the moment of inertia and compactness of neutron stars in this theory. We show that in a certain range of the theory's parameter space the universal relation largely deviates from that of General Relativity, allowing, in principle, to probe the existence of spontaneous scalarization with future observations.

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“…Similar cosmological models which make use of a disformal coupling have been discussed in Refs. [50][51][52][53][54][55][56][57][58][59][60]. We here re-examine and update the constraints in these coupled dark energy scenarios.…”

Section: Introductionmentioning

confidence: 99%

Searching for dark matter-dark energy interactions: Going beyond the conformal case

Bruck

Mifsud

2018

Phys. Rev. D

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We consider a generic cosmological model which allows for non-gravitational direct couplings between dark matter and dark energy. The distinguishing cosmological features of these couplings can be probed by current cosmological observations, thus enabling us to place constraints on this generic interaction which is composed of the conformal and disformal coupling functions. We perform a global analysis in order to independently constrain the conformal, disformal, and mixed interactions between dark matter and dark energy by combining current data from: Planck observations of the cosmic microwave background radiation anisotropies, a combination of measurements of baryon acoustic oscillations, a supernovae Type Ia sample, a compilation of Hubble parameter measurements estimated from the cosmic chronometers approach, direct measurements of the expansion rate of the Universe today, and a compilation of growth of structure measurements. We find that in these coupled dark energy models, the influence of the local value of the Hubble constant does not significantly alter the inferred constraints when we consider joint analyses that include all cosmological probes. Moreover, the parameter constraints are remarkably improved with the inclusion of the growth of structure data set measurements. We find no compelling evidence for an interaction within the dark sector of the Universe.

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The variation of the fine-structure constant from disformal couplings

Cited by 34 publications

References 130 publications

Testing coupled dark energy models with their cosmological background evolution

Testing coupled dark energy models with their cosmological background evolution

Relativistic stars in scalar-tensor theories with disformal coupling

Searching for dark matter-dark energy interactions: Going beyond the conformal case

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