Born-Infeld gravity with a Brans-Dicke scalar

Born-Infeld gravity with a Brans-Dicke scalar Recently proposed Born-Infeld (BI) theories of gravity assume a constant BI parameter (κ). However, no clear consensus exists on the sign and value of κ. Recalling the Brans-Dicke (BD) approach, where a scalar field was used to generate the gravitational constant G, we suggest an extension of Born-Infeld gravity with a similar Brans-Dicke flavor. Thus, a new action, with κ elevated to a spacetime dependent real scalar field, is proposed. We illustrate this new theory in a cosmological setting with pressureless dust and radiation as matter. Assuming a functional form of κ(t), we numerically obtain the scale factor evolution and other details of the background cosmology. It is known that BI gravity differs from general relativity (GR) in the strong-field regime but reduces to GR for intermediate and weak fields. Our studies in cosmology demonstrate how, with this new, scalar-tensor BI gravity, deviations from GR, as well as usual BI gravity, may arise in the weak-field regime too. For example, we note a late-time acceleration without any dark energy contribution. Apart from such qualitative differences, we note that fixing the sign and value of κ is no longer a necessity in this theory, though the origin of the BD scalar does remain an open question. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Physical Review D American Physical Society (APS)

Born-Infeld gravity with a Brans-Dicke scalar

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Born-Infeld gravity with a Brans-Dicke scalar

Abstract

Recently proposed Born-Infeld (BI) theories of gravity assume a constant BI parameter (κ). However, no clear consensus exists on the sign and value of κ. Recalling the Brans-Dicke (BD) approach, where a scalar field was used to generate the gravitational constant G, we suggest an extension of Born-Infeld gravity with a similar Brans-Dicke flavor. Thus, a new action, with κ elevated to a spacetime dependent real scalar field, is proposed. We illustrate this new theory in a cosmological setting with pressureless dust and radiation as matter. Assuming a functional form of κ(t), we numerically obtain the scale factor evolution and other details of the background cosmology. It is known that BI gravity differs from general relativity (GR) in the strong-field regime but reduces to GR for intermediate and weak fields. Our studies in cosmology demonstrate how, with this new, scalar-tensor BI gravity, deviations from GR, as well as usual BI gravity, may arise in the weak-field regime too. For example, we note a late-time acceleration without any dark energy contribution. Apart from such qualitative differences, we note that fixing the sign and value of κ is no longer a necessity in this theory, though the origin of the BD scalar does remain an open question.
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Publisher
The American Physical Society
Copyright
Copyright © © 2017 American Physical Society
ISSN
1550-7998
eISSN
1550-2368
D.O.I.
10.1103/PhysRevD.96.024050
Publisher site
See Article on Publisher Site

Abstract

Recently proposed Born-Infeld (BI) theories of gravity assume a constant BI parameter (κ). However, no clear consensus exists on the sign and value of κ. Recalling the Brans-Dicke (BD) approach, where a scalar field was used to generate the gravitational constant G, we suggest an extension of Born-Infeld gravity with a similar Brans-Dicke flavor. Thus, a new action, with κ elevated to a spacetime dependent real scalar field, is proposed. We illustrate this new theory in a cosmological setting with pressureless dust and radiation as matter. Assuming a functional form of κ(t), we numerically obtain the scale factor evolution and other details of the background cosmology. It is known that BI gravity differs from general relativity (GR) in the strong-field regime but reduces to GR for intermediate and weak fields. Our studies in cosmology demonstrate how, with this new, scalar-tensor BI gravity, deviations from GR, as well as usual BI gravity, may arise in the weak-field regime too. For example, we note a late-time acceleration without any dark energy contribution. Apart from such qualitative differences, we note that fixing the sign and value of κ is no longer a necessity in this theory, though the origin of the BD scalar does remain an open question.

Journal

Physical Review DAmerican Physical Society (APS)

Published: Jul 15, 2017

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