Beyond the Cosmological Standard Model

By A. Joyce, B. Jain, J. Khoury, M. Trodden. 2014

1,111 citations recorded by the source corpus.

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 \Lambda, 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 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 become important, and those for which second derivatives 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 and massive gravity theories, employing the Vainshtein mechanism. In each case, we describe the theories as effective theories. We describe experimental tests, summarizing laboratory and solar system tests and describing in some detail astrophysical and cosmological tests. We discuss future tests which will be sensitive to different signatures of new physics in the gravitational sector. Parts that are more relevant to theorists vs. observers/experimentalists are clearly indicated, in the hope that this will serve as a useful reference for both audiences, as well as helping those interested in bridging the gap between them.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/1da97e5318dc142384aa8228feacfc1e5aef96b6

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Citations in the corpus

Effective field theory of dark energy: A review (2019, background): “The GR limit is then recovered in such models thanks to screening mechanisms [5].”
Weighing the giants – IV. Cosmology and neutrino mass (2014, methodology): “In particular, various modifications to GR in the largescale/weak-field limit have been proposed (for recent reviews see, e.g., Frieman et al. 2008; Clifton et al. 2012; Joyce et al. 2014).”
Cosmological tests of modified gravity (2015, methodology): “In this section we follow [11] and classify the screening mechanisms.”
General Relativity and Cosmology: Unsolved Questions and Future Directions (2016, background): “The landscape of alternative cosmological models is even larger if we relax our assumptions on the theory of gravity [520].”
A systematic approach to generalisations of General Relativity and their cosmological implications (2018, background): “This is shown in figure 7 taken from the pioneering work [40] (see also the exhaustive review [24] for a detail exposure to screening mechanisms).”
Probing dark energy with atom interferometry (2014, background): “Within quantum field theory, the natural explanation requires a new scalar field, but such a field should produce a new force [2].”
Accurate halo-model matter power spectra with dark energy, massive neutrinos and modified gravitational forces (2016, background): “Recent reviews of some of the menagerie of possible MG theories are given by Joyce et al. (2015) and Koyama (2016).”
Horndeski theory and beyond: a review (2019, background): “We will not describe much about cosmological tests of gravity, which are covered by excellent reviews such as [13, 14, 15].”