Proves equivalence of redundant Goldstone and adjoint-matter formulations of SK EFTs for non-Abelian symmetries and extends both to all orders in ħω/T while classifying invariant kernels under DKMS and unitarity.
Null energy condition and superluminal propagation
8 Pith papers cite this work. Polarity classification is still indexing.
8
Pith papers citing it
abstract
We study whether a violation of the null energy condition necessarily implies the presence of instabilities. We prove that this is the case in a large class of situations, including isotropic solids and fluids relevant for cosmology. On the other hand we present several counter-examples of consistent effective field theories possessing a stable background where the null energy condition is violated. Two necessary features of these counter-examples are the lack of isotropy of the background and the presence of superluminal modes. We argue that many of the properties of massive gravity can be understood by associating it to a solid at the edge of violating the null energy condition. We briefly analyze the difficulties of mimicking $\dot H>0$ in scalar tensor theories of gravity.
citation-role summary
background 1
citation-polarity summary
verdicts
UNVERDICTED 8roles
background 1polarities
background 1representative citing papers
A generalized Chaplygin-type solid unifies dark matter and dark energy via an early pressureless phase transitioning to a late solid phase that supports acceleration and produces distinct low-redshift perturbation signatures.
Affine ANEC obstructs non-static flat and open FRW from being null geodesically complete while ANEC-satisfying, but allows explicit scalar-field realizations for closed FRW with NEC-respecting matter.
Phantom Chaplygin gas forces the Einstein-frame lapse to change sign smoothly while the causal-frame lapse stays positive, yielding a robust non-singular bounce even with extra matter.
A covariant model of Dirac fermions with an extra Planck-derived term yields the same Einstein-equation collapse as ordinary GR yet permits numerical trajectories that escape the black hole.
Local HII galaxy and cosmic chronometer data favor the Rh=ct universe over ΛCDM at 92% vs 8% likelihood, with Rh=ct satisfying all energy conditions while ΛCDM violates the strong energy condition at z≲2.
Bouncing solutions in quadratic curvature gravity with a scalar field satisfy null, weak, and dominant energy conditions but violate the strong one when using the scalar-field energy-momentum tensor, while all four conditions are violated near the bounce in the effective tensor formulation.
Effective phantom dark energy is a background-level reconstruction that does not imply fundamental pathologies such as ghost instabilities or null energy condition violation by the underlying stress tensor.
citing papers explorer
-
A solid unification of the dark sector
A generalized Chaplygin-type solid unifies dark matter and dark energy via an early pressureless phase transitioning to a late solid phase that supports acceleration and produces distinct low-redshift perturbation signatures.
-
The energy conditions and model selection in the local Universe
Local HII galaxy and cosmic chronometer data favor the Rh=ct universe over ΛCDM at 92% vs 8% likelihood, with Rh=ct satisfying all energy conditions while ΛCDM violates the strong energy condition at z≲2.
-
Effective Phantom Dark Energy: What Cosmological Reconstruction Does and Does Not Imply
Effective phantom dark energy is a background-level reconstruction that does not imply fundamental pathologies such as ghost instabilities or null energy condition violation by the underlying stress tensor.