Restricted Galileons

Berezhiani, Lasha; Chkareuli, Giga; Gabadadze, Gregory

doi:10.1103/physrevd.88.124020

Cited by 73 publications

(153 citation statements)

References 71 publications

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“…A related tension is that the galileon terms lead to scattering amplitudes which do not obey dispersion relations obtained from arguments about S-matrix analyticity, discussed in Appendix D.4. On the other hand, this argument relies on the existence of an S-matrix for galileons, which has been questioned recently in [589,590].…”

Section: Perturbations Around the Spherically-symmetric Backgroundmentioning

confidence: 99%

Beyond the cosmological standard model

et al. 2015

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After a decade and a half of research motivated by the accelerating universe, theory and experiment have a reached a certain level of maturity. The development of theoretical models beyond Λ or smooth dark energy, often called modified gravity, has led to broader insights into a path forward, and a host of observational and experimental tests have been developed. In this review we present the current state of the field and describe a framework for anticipating developments in the next decade. We identify the guiding principles for rigorous and consistent modifications of the standard model, and discuss the prospects for empirical tests.We begin by reviewing recent attempts to consistently modify Einstein gravity in the infrared, focusing on the notion that additional degrees of freedom introduced by the modification must "screen" themselves from local tests of gravity. We categorize screening mechanisms into three broad classes: mechanisms which become active in regions of high Newtonian potential, those in which first derivatives of the field become important, and those for which second derivatives of the field are important. Examples of the first class, such as f (R) gravity, employ the familiar chameleon or symmetron mechanisms, whereas examples of the last class are galileon and massive gravity theories, employing the Vainshtein mechanism. In each case, we describe the theories as effective theories and discuss prospects for completion in a more fundamental theory. We describe experimental tests of each class of theories, summarizing laboratory and solar system tests and describing in some detail astrophysical and cosmological tests. Finally, we discuss prospects for future tests which will be sensitive to different signatures of new physics in the gravitational sector.The review is structured so that those parts that are more relevant to theorists vs. observers/experimentalists are clearly indicated, in the hope that this will serve as a useful reference for both audiences, as well as helping those interested in bridging the gap between them.

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Section: Perturbations Around the Spherically-symmetric Backgroundmentioning

confidence: 99%

Beyond the cosmological standard model

et al. 2015

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“…In the context of nonlinear massive gravity the implementation of this Vainshtein mechanism was considered for instance in [12,14,43,44]. At the nonlinear level the theory involves interactions of the form h(∂ 2χ ) n+1 /Λ 3n 3 , which implies that the theory is strongly coupled at the scale Λ 3 [8,27].…”

Section: Jhep04(2016)188mentioning

confidence: 99%

“…It has been shown that homogeneous and isotropic cosmological solutions, as well as static, spherically symmetric black holes, in ghost-free massive gravity are absent/unstable [43,44,48], and it has been argued that the "natural" cosmological solutions in ghost-free massive gravity are inhomogeneous/anisotropic and the "natural" black hole solutions are non-static/spherically symmetric, the deviations from the exact symmetries being typically of O(m 2 ). In the Λ 2 decoupling limit, we are forced to break Lorentz symmetries in order to have stable backgrounds, and indeed we expect that it is the Λ 2 decoupling limit that is the most appropriate description of the generic inhomogenous cosmologies in massive gravity.…”

Section: Jhep04(2016)188mentioning

confidence: 99%

The Λ2 limit of massive gravity

Rham

Tolley

Zhou

2016

J. High Energ. Phys.

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Lorentz-invariant massive gravity is usually associated with a strong coupling scale Λ 3 . By including non-trivial effects from the Stückelberg modes, we show that about these vacua, one can push the strong coupling scale to higher values and evade the linear vDVZ-discontinuity. For generic parameters of the theory and generic vacua for the Stückelberg fields, the Λ 2 -decoupling limit of the theory is well-behaved and free of any ghost or gradient-like instabilities. We also discuss the implications for nonlinear sigma models with Lorentzian target spaces.

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“…This problem can be avoided if the non-abelian flavor symmetry is gauged, giving mass to the Goldstone modes. 1 Anomaly cancellation in such a theory requires introduction of exotic fermions [10][11][12][13][14][15] to cancel gauge anomalies. These mix with the SM fermions.…”

Section: Introductionmentioning

confidence: 99%

Higgs-flavon mixing and LHC phenomenology in a simplified model of broken flavor symmetry

et al. 2014

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The LHC phenomenology of a low-scale gauged flavor symmetry model with inverted hierarchy is studied, through introduction of a simplified model of broken flavor symmetry. A new scalar (a flavon) and a new neutral top-philic massive gauge boson emerge with mass in the TeV range along with a new heavy fermion associated with the standard model top quark. After checking constraints from electroweak precision observables, we investigate the influence of the model on Higgs boson physics, notably on its production cross section and decay branching fractions. Limits on the flavon ϕ from heavy Higgs boson searches at the LHC at 7 and 8 TeV are presented. The branching fractions of the flavon are computed as a function of the flavon mass and the Higgs-flavon mixing angle. We also explore possible discovery of the flavon at 14 TeV, particularly via the ϕ → Z 0 Z 0 decay channel in the 2 2 final state, and through standard model Higgs boson pair production ϕ → hh in the bbγγ final state. We conclude that the flavon mass range up to 500 GeV could probed down to quite small values of the Higgs-flavon mixing angle with 100 fb −1 of integrated luminosity at 14 TeV.

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Restricted Galileons

Cited by 73 publications

References 71 publications

Beyond the cosmological standard model

Beyond the cosmological standard model

The Λ2 limit of massive gravity

Higgs-flavon mixing and LHC phenomenology in a simplified model of broken flavor symmetry

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