Vacuum Cherenkov radiation and bremsstrahlung from disformal couplings

Bruck, Carsten van de; Burrage, Clare; Morrice, Jack

doi:10.1088/1475-7516/2016/08/003

Cited by 19 publications

(20 citation statements)

References 28 publications

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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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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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“…If M i = M then the field couples to all species universally and there is no violation of the equivalence principle. But there is no a priori reason for one to expect this to be the case and, in particular, reference [79] have investigated the effects of having different disformal couplings to photons and baryons. In the simplest case where there is no disformal coupling to matter 9 , the 9 More complicated theories where the cosmic accelera- speed of photons is given by [81], which implies that M γ > ∼ 10 MeV.…”

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confidence: 99%

Implications of the Neutron Star Merger GW170817 for Cosmological Scalar-Tensor Theories

2017

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The LIGO and VIRGO Collaborations have recently announced the detection of gravitational waves from a neutron star-neutron star merger (GW170817) and the simultaneous measurement of an optical counterpart (the γ-ray burst GRB 170817A). The close arrival time of the gravitational and electromagnetic waves limits the difference in speed of photons and gravitons to be less than about 1 part in 10^{15}. This has three important implications for cosmological scalar-tensor gravity theories that are often touted as dark energy candidates and alternatives to the Λ cold dark matter model. First, for the most general scalar-tensor theories-beyond Horndeski models-three of the five parameters appearing in the effective theory of dark energy can now be severely constrained on astrophysical scales; we present the results of combining the new gravity wave results with galaxy cluster observations. Second, the combination with the lack of strong equivalence principle violations exhibited by the supermassive black hole in M87 constrains the quartic galileon model to be cosmologically irrelevant. Finally, we derive a new bound on the disformal coupling to photons that implies that such couplings are irrelevant for the cosmic evolution of the field.

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“…where we have set Ḡ2,X " ´1{2 for a canonically normalised field and kept only the leading terms, for instance expanding Cpφq " 1 `c φ φ{M P `O `1{M 2 P ˘12 . The characteristic scale M 4 " M P Λ 3 {|β 1 | of the disformal coupling between matter and a light scalar field has been constrained via a number of astrophysical and terrestrial experiments [153][154][155][156][157][158][159][160][161][162][163][164][165][166][167][168][169]. For typical dark energy values, pΛ 3 " M P H 2 0 q, the coupling is much too large and such a theory would be ruled out by these observations unless some screening mechanism takes place.…”

Section: Strong Coupling and Classical Non-linearitymentioning

confidence: 99%

Scalar Fields Near Compact Objects: Resummation versus UV Completion

Davis,

Melville

2021

Preprint

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Low-energy effective field theories containing a light scalar field are used extensively in cosmology, but often there is a tension between embedding such theories in a healthy UV completion and achieving a phenomenologically viable screening mechanism in the IR. Here, we identify the range of interaction couplings which allow for a smooth resummation of classical non-linearities (necessary for kinetic/Vainshtein-type screening), and compare this with the range allowed by unitarity, causality and locality in the underlying UV theory. The latter region is identified using positivity bounds on the 2 Ñ 2 scattering amplitude, and in particular by considering scattering about a non-trivial background for the scalar we are able to place constraints on interactions at all orders in the field (beyond quartic order). We identify two classes of theories can both exhibit screening and satisfy existing positivity bounds, namely scalar-tensor theories of P pXq or quartic Horndeski type in which the leading interaction contains an odd power of X. Finally, for the quartic DBI Galileon (equivalent to a disformally coupled scalar in the Einstein frame), the analogous resummation can be performed near two-body systems and imposing positivity constraints introduces a nonperturbative ambiguity in the screened scalar profile. These results will guide future searches for UV complete models which exhibit screening of fifth forces in the IR.

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Vacuum Cherenkov radiation and bremsstrahlung from disformal couplings

Cited by 19 publications

References 28 publications

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

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

Implications of the Neutron Star Merger GW170817 for Cosmological Scalar-Tensor Theories

Scalar Fields Near Compact Objects: Resummation versus UV Completion

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