Stability of scalar perturbations in scalar-torsion f(T,ϕ) gravity theories in the presence of a matter fluid

Abstract Light fields with spatially varying backgrounds can modulate cosmic preheating, and imprint the nonlinear effects of preheating dynamics at tiny scales on large scale fluctuations. This provides us a unique probe into the preheating era which we dub the “cosmic microscope”. We identify a distinctive effect of preheating on scalar perturbations that turns the Gaussian primordial fluctuations of a light scalar field into square waves, like a diode. The effect manifests itself as local non-Gaussianity. We present a model, “modulated partial preheating”, where this nonlinear effect is consistent with current observations and can be reached by near future cosmic probes.

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The Weyl double copy from twistor space

Journal of High Energy Physics ◽

10.1007/jhep05(2021)239 ◽

2021 ◽

Vol 2021 (5) ◽

Author(s):

Erick Chacón ◽

Silvia Nagy ◽

Chris D. White

Keyword(s):

Exact Solutions ◽

Twistor Space ◽

Current Form ◽

New Formalism ◽

Petrov Types ◽

Gravity Theories ◽

Double Copy

Abstract The Weyl double copy is a procedure for relating exact solutions in biadjoint scalar, gauge and gravity theories, and relates fields in spacetime directly. Where this procedure comes from, and how general it is, have until recently remained mysterious. In this paper, we show how the current form and scope of the Weyl double copy can be derived from a certain procedure in twistor space. The new formalism shows that the Weyl double copy is more general than previously thought, applying in particular to gravity solutions with arbitrary Petrov types. We comment on how to obtain anti-self-dual as well as self-dual fields, and clarify some conceptual issues in the twistor approach.

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A generalized Kasner transition for bouncing Bianchi I models in modified gravity theories

Journal of Cosmology and Astroparticle Physics ◽

10.1088/1475-7516/2019/12/039 ◽

2019 ◽

Vol 2019 (12) ◽

pp. 039-039 ◽

Cited By ~ 3

Author(s):

Marco de Cesare ◽

Edward Wilson-Ewing

Keyword(s):

Modified Gravity ◽

Bianchi I ◽

Modified Gravity Theories ◽

Gravity Theories

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Relating Gauge and Gravity Theories in the Large Mass Limit

Physical Review Letters ◽

10.1103/physrevlett.125.181603 ◽

2020 ◽

Vol 125 (18) ◽

Cited By ~ 5

Author(s):

Kays Haddad ◽

Andreas Helset

Keyword(s):

Large Mass ◽

Mass Limit ◽

Gravity Theories

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Noisy effects in interferometric quantum gravity tests

International Journal of Quantum Information ◽

10.1142/s0219749917400147 ◽

2017 ◽

Vol 15 (08) ◽

pp. 1740014 ◽

Cited By ~ 2

Author(s):

F. Benatti ◽

R. Floreanini ◽

S. Olivares ◽

E. Sindici

Keyword(s):

Quantum Gravity ◽

Weak Coupling ◽

Scale Effects ◽

External Environment ◽

Planck Scale ◽

Canonical Commutation Relations ◽

Commutation Relations ◽

Photon Propagation ◽

Gravity Theories ◽

Planck Scale Effects

Quantum-enhanced metrology is boosting interferometer sensitivities to extraordinary levels, up to the point where table-top experiments have been proposed to measure Planck-scale effects predicted by quantum gravity theories. In setups involving multiple photon interferometers, as those for measuring the so-called holographic fluctuations, entanglement provides substantial improvements in sensitivity. Entanglement is however a fragile resource and may be endangered by decoherence phenomena. We analyze how noisy effects arising either from the weak coupling to an external environment or from the modification of the canonical commutation relations in photon propagation may affect this entanglement-enhanced gain in sensitivity.

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