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Modern tests of Lorentz invariance
 Living Rev. Rel
"... Motivated by ideas about quantum gravity, a tremendous amount of effort over the past decade has gone into testing Lorentz invariance in various regimes. This review summarizes both the theoretical frameworks for tests of Lorentz invariance and experimental advances that have made such high precisio ..."
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Motivated by ideas about quantum gravity, a tremendous amount of effort over the past decade has gone into testing Lorentz invariance in various regimes. This review summarizes both the theoretical frameworks for tests of Lorentz invariance and experimental advances that have made such high precision tests possible. The current constraints on Lorentz violating effects from both terrestrial experiments and astrophysical observations are presented.
Caustic avoidance in HoravaLifshitz gravity
, 2009
"... There are at least four versions of HoravaLishitz gravity in the literature. We consider the version without the detailed balance condition with the projectability condition and address one aspect of the theory: avoidance of caustics for constant time hypersurfaces. We show that there is no caustic ..."
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Cited by 11 (1 self)
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There are at least four versions of HoravaLishitz gravity in the literature. We consider the version without the detailed balance condition with the projectability condition and address one aspect of the theory: avoidance of caustics for constant time hypersurfaces. We show that there is no caustic with plane symmetry in the absence of matter source if λ ̸ = 1. If λ = 1 is a stable IR fixed point of the renormalization group flow then λ is expected to deviate from 1 near wouldbe caustics, where the extrinsic curvature increases and highenergy corrections become important. Therefore, the absence of caustics with λ ̸ = 1 implies that caustics cannot form with this symmetry in the absence of matter source. We argue that inclusion of matter source will not change the conclusion. We also argue that caustics with codimension higher than one will not form because of repulsive gravity generated by nonlinear higher curvature terms. These arguments support our conjecture that there is no caustic for constant time hypersurfaces. Finally,
String theoretic bounds on Lorentzviolating warped compactification
 JHEP
"... Abstract: We consider warped compactifications that solve the 10 dimensional supergravity equations of motion at a point, stabilize the position of a D3brane world, and admit a warp factor that violates Lorentz invariance along the brane. This gives a string embedding of “asymmetrically warped ” mo ..."
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Abstract: We consider warped compactifications that solve the 10 dimensional supergravity equations of motion at a point, stabilize the position of a D3brane world, and admit a warp factor that violates Lorentz invariance along the brane. This gives a string embedding of “asymmetrically warped ” models which we use to calculate stringy (α ′ ) corrections to standard model dispersion relations, paying attention to the maximum speeds for different particles. We find, from the dispersion relations, limits on gravitational Lorentz violation in these models, improving on current limits on the speed of graviton propagation, including those derived from field theoretic loops. We comment on the viability of models that use
PauliFierz gravitons on FriedmannRobertsonWalker background
, 2009
"... We derive the Hamiltonian describing PauliFierz massive gravitons on a flat FriedmannRobertsonWalker (FRW) cosmology. The cosmological evolution is driven by a scalar field Φ with an arbitrary potential V (Φ). The model contains two coupled scalar modes, corresponding to the fluctuations of Φ and ..."
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We derive the Hamiltonian describing PauliFierz massive gravitons on a flat FriedmannRobertsonWalker (FRW) cosmology. The cosmological evolution is driven by a scalar field Φ with an arbitrary potential V (Φ). The model contains two coupled scalar modes, corresponding to the fluctuations of Φ and to the propagating scalar component of the PauliFierz graviton. In order to preserve the full gauge invariance of the massless version of the theory, both modes have to be taken into account. We canonically normalize the Hamiltonian and generalize the Higuchi bound to FRW backgrounds. We discuss how this bound can set limits on the value of the PauliFierz mass parameter. We also observe that on a generic FRW background the speed of propagation of the scalar mode of the graviton is always smaller than the speed of light.
Beyond the Cosmological Standard Model
, 2014
"... 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 ..."
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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
Constraining the New Aether: Gravitational
, 2005
"... Abstract: We study the simplest concrete theory for spontaneous Lorentz violation, the “New Aether Theory ” of Jacobson and Mattingly, which is a vectortensor gravitational theory with a fixedmodulus condition on the vector field. We show that the observation of ultrahigh energy cosmic rays (whic ..."
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Abstract: We study the simplest concrete theory for spontaneous Lorentz violation, the “New Aether Theory ” of Jacobson and Mattingly, which is a vectortensor gravitational theory with a fixedmodulus condition on the vector field. We show that the observation of ultrahigh energy cosmic rays (which implies the absence of energy loss via various Cherenkov type processes) places constraints on the parameters of this theory, which are much stronger than those previously found in the literature and are also stronger than the constraints generically arising when gravity
EINSTEINÆTHER THEORY ∗
, 2004
"... We review the status of “EinsteinÆther theory”, a generally covariant theory of gravity coupled to a dynamical, unit timelike vector field that breaks local Lorentz symmetry. Aspects of waves, stars, black holes, and cosmology are discussed, together with theoretical and observational constraints. ..."
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We review the status of “EinsteinÆther theory”, a generally covariant theory of gravity coupled to a dynamical, unit timelike vector field that breaks local Lorentz symmetry. Aspects of waves, stars, black holes, and cosmology are discussed, together with theoretical and observational constraints. Open questions are stressed. 1.
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, 809
"... Efforts to place limits on deviations from canonical formulations of electromagnetism and gravity have probed length scales increasing dramatically over time. Historically, these studies have passed through three stages: (1) Testing the power in the inversesquare laws of Newton and Coulomb, (2) See ..."
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Efforts to place limits on deviations from canonical formulations of electromagnetism and gravity have probed length scales increasing dramatically over time. Historically, these studies have passed through three stages: (1) Testing the power in the inversesquare laws of Newton and Coulomb, (2) Seeking a nonzero value for the rest mass of photon or graviton, (3) Considering more degrees of