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Title: Unitarity and the Vainshtein mechanism

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Journal Article: Publisher's Accepted Manuscript
Journal Name:
Physical Review D
Additional Journal Information:
Journal Volume: 91; Journal Issue: 4; Journal ID: ISSN 1550-7998
American Physical Society
Country of Publication:
United States

Citation Formats

Kaloper, Nemanja, Padilla, Antonio, Saffin, Paul M., and Stefanyszyn, David. Unitarity and the Vainshtein mechanism. United States: N. p., 2015. Web. doi:10.1103/PhysRevD.91.045017.
Kaloper, Nemanja, Padilla, Antonio, Saffin, Paul M., & Stefanyszyn, David. Unitarity and the Vainshtein mechanism. United States. doi:10.1103/PhysRevD.91.045017.
Kaloper, Nemanja, Padilla, Antonio, Saffin, Paul M., and Stefanyszyn, David. 2015. "Unitarity and the Vainshtein mechanism". United States. doi:10.1103/PhysRevD.91.045017.
title = {Unitarity and the Vainshtein mechanism},
author = {Kaloper, Nemanja and Padilla, Antonio and Saffin, Paul M. and Stefanyszyn, David},
abstractNote = {},
doi = {10.1103/PhysRevD.91.045017},
journal = {Physical Review D},
number = 4,
volume = 91,
place = {United States},
year = 2015,
month = 2

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1103/PhysRevD.91.045017

Citation Metrics:
Cited by: 14works
Citation information provided by
Web of Science

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  • We study in detail static spherically symmetric solutions of nonlinear Pauli-Fierz theory. We obtain a numerical solution with a constant density source. This solution shows a recovery of the corresponding solution of general relativity via the Vainshtein mechanism. This result has already been presented by us in a recent paper, and we give here more detailed information on it as well as on the procedure used to obtain it. We give new analytic insights into this problem, in particular, for what concerns the question of the number of solutions at infinity. We also present a weak-field limit which allows onemore » to capture all the salient features of the numerical solution, including the Vainshtein crossover and the Yukawa decay.« less
  • There has been a lot of research interest in modified gravity theories which utilise the Vainshtein mechanism to recover standard general relativity in regions with high matter density, such as the Dvali-Gabadadze-Porrati and Galileon models. The strong nonlinearity in the field equations of these theories implies that accurate theoretical predictions could only be made using high-resolution cosmological simulations. Previously, such simulations were usually done on regular meshes, which limits both their performance and the accuracy. In this paper, we report the development of a new algorithm and code, based on ECOSMOG, that uses adaptive mesh refinements to improve the efficiencymore » and precision in simulating the models with Vainshtein mechanism. We have made various code tests against the numerical reliability, and found consistency with previous simulations. We also studied the velocity field in the self-accelerating branch of the DGP model. The code, parallelised using MPI, is suitable for large cosmological simulations of Galileon-type modified gravity theories.« less
  • We reinvestigate the fate of the Vainhstein mechanism in the minimal model of dRGT massive gravity. As the latter is characterised by the complete absence of interactions in the decoupling limit, we study their structure at higher energies. We show that in static spherically symmetric configurations, the lowest energy scale of interactions is pushed up to the Planck mass. This fact points towards an absence of Vainshtein mechanism in this framework, but does not prove it. By resorting to the exact vacuum equations of motion, we show that there is indeed an obstruction that precludes any recovery of General Relativitymore » under the conditions of stationarity and spherical symmetry. However, we argue that the latter are too restrictive and might miss some important physical phenomena. Indeed, we point out that in generic non spherically symmetric or time-dependent situations, interactions arising at energies arbitrarily close to the energy scale of the decoupling limit reappear. This leads us to question whether the small degree of spherical symmetry breaking in the solar system can be sufficient to give rise to a successful Vainshtein mechanism.« less
  • We investigate the dependence of the Vainshtein screening mechanism on the cosmic web morphology of both dark matter particles and halos as determined by ORIGAMI. Unlike chameleon and symmetron screening, which come into effect in regions of high density, Vainshtein screening instead depends on the dimensionality of the system, and screened bodies can still feel external fields. ORIGAMI is well-suited to this problem because it defines morphologies according to the dimensionality of the collapsing structure and does not depend on a smoothing scale or density threshold parameter. We find that halo particles are screened while filament, wall, and void particlesmore » are unscreened, and this is independent of the particle density. However, after separating halos according to their large scale cosmic web environment, we find no difference in the screening properties of halos in filaments versus halos in clusters. We find that the fifth force enhancement of dark matter particles in halos is greatest well outside the virial radius. We confirm the theoretical expectation that even if the internal field is suppressed by the Vainshtein mechanism, the object still feels the fifth force generated by the external fields, by measuring peculiar velocities and velocity dispersions of halos. Finally, we investigate the morphology and gravity model dependence of halo spins, concentrations, and shapes.« less
  • We investigate the observational consequences of scalar instabilities in bimetric theory, under the assumption that the Vainshtein mechanism restores general relativity within a certain distance from gravitational sources. We argue that early time instabilities have a negligible impact on observed structures. Assuming that the instabilities affect sub-horizon density fluctuations, we constrain the redshift, z{sub i}, below which instabilities are ruled out. For the ''minimal'' β{sub 1}-model, observational constraints are close to the theoretical expectations of z{sub i≈} 0.5, potentially allowing the model to be ruled in or out with a more detailed study, possibly including secondary cosmic microwave background constraints.