All Outputs (33)

CMB constraints on cosmic strings and superstrings (2016)
Journal Article
Charnock, T., Avgoustidis, A., Copeland, E. J., & Moss, A. (2016). CMB constraints on cosmic strings and superstrings. Physical Review D - Particles, Fields, Gravitation and Cosmology, 93(12), Article 123503. https://doi.org/10.1103/PhysRevD.93.123503

We present the first complete MCMC analysis of cosmological models with evolving cosmic (super)string networks, using the Unconnected Segment Model in the unequal-time correlator formalism. For ordinary cosmic string networks, we derive joint constra... Read More about CMB constraints on cosmic strings and superstrings.

Dark energy in light of the discovery of the Higgs (2015)
Journal Article
Copeland, E. J. (2016). Dark energy in light of the discovery of the Higgs. Annalen der Physik, 528(1-2), 62-67. https://doi.org/10.1002/andp.201500163

We discuss the impact the observation of the Higgs Boson has had on models of Dark Energy.

Using atom interferometry to detect dark energy (2015)
Journal Article
Burrage, C., & Copeland, E. J. (in press). Using atom interferometry to detect dark energy. Contemporary Physics, 57(2), https://doi.org/10.1080/00107514.2015.1060058

We review the tantalising prospect that the first evidence for the dark energy driving the observed acceleration of the Universe on giga-parsec scales may be found through metre scale laboratory based atom interferometry experiments. To do that, we f... Read More about Using atom interferometry to detect dark energy.

Asymptotically safe Starobinsky inflation (2015)
Journal Article
Copeland, E. J., Rahmede, C., & Saltas, I. D. (2015). Asymptotically safe Starobinsky inflation. Physical Review D, 91(10), https://doi.org/10.1103/PhysRevD.91.103530

We revisit Starobinsky inflation in a quantum gravitational context, by means of the exact renormalization group (RG). We calculate the nonperturbative beta functions for Newton’s “constant” G and the dimensionless R^2 coupling, and show that there e... Read More about Asymptotically safe Starobinsky inflation.

Ellipticity weakens chameleon screening (2015)
Journal Article
Burrage, C., Copeland, E. J., & Stevenson, J. (2015). Ellipticity weakens chameleon screening. Physical Review D, D91(6), Article 065030. https://doi.org/10.1103/PhysRevD.91.065030

The chameleon mechanism enables a long-range fifth force to be screened in dense environments when nontrivial self-interactions of the field cause its mass to increase with the local density. To date, chameleon fifth forces have mainly been studied f... Read More about Ellipticity weakens chameleon screening.

Probing dark energy with atom interferometry (2015)
Journal Article
Burrage, C., Copeland, E. J., & Hinds, E. A. (2015). Probing dark energy with atom interferometry. Journal of Cosmology and Astroparticle Physics, 2015(3), Article 042. https://doi.org/10.1088/1475-7516/2015/03/042

© 2015 IOP Publishing Ltd and Sissa Medialab srl. Theories of dark energy require a screening mechanism to explain why the associated scalar fields do not mediate observable long range fifth forces. The archetype of this is the chameleon field. Here... Read More about Probing dark energy with atom interferometry.

Charge-swapping q balls (2014)
Journal Article
Copeland, E. J., Saffin, P. M., & Zhou, S. Y. (2014). Charge-swapping q balls. Physical Review Letters, 113(23), https://doi.org/10.1103/PhysRevLett.113.231603

© 2014 American Physical Society. Q balls are nontopological solitonic solutions to a wide class of field theories that possess global symmetries. Here we show that in these same theories there also exists a tower of novel composite Q-ball solutions... Read More about Charge-swapping q balls.

The cosmology of the Fab-Four (2012)
Journal Article
Copeland, E. J., Padilla, A., & Saffin, P. M. (2012). The cosmology of the Fab-Four. Journal of Cosmology and Astroparticle Physics, 2012(12), Article 026. https://doi.org/10.1088/1475-7516/2012/12/026

We have recently proposed a novel self tuning mechanism to alleviate the famous cosmological constant problem, based on the general scalar tensor theory proposed by Horndeski. The self-tuning model ends up consisting of four geometric terms in the ac... Read More about The cosmology of the Fab-Four.

Self-tuning and the derivation of a class of scalar-tensor theories (2012)
Journal Article
Charmousis, C., Copeland, E. J., Padilla, A., & Saffin, P. M. (2012). Self-tuning and the derivation of a class of scalar-tensor theories. Physical Review D, 85(10), Article 104040. https://doi.org/10.1103/PhysRevD.85.104040

We have recently proposed a special class of scalar tensor theories known as the Fab Four. These arose from attempts to analyse the cosmological constant problem within the context of Horndeski's most general scalar tensor theory. The Fab Four togeth... Read More about Self-tuning and the derivation of a class of scalar-tensor theories.

General second-order scalar-tensor theory and self-tuning (2012)
Journal Article
Charmousis, C., Copeland, E. J., Saffin, P. M., & Padilla, A. (2012). General second-order scalar-tensor theory and self-tuning. Physical Review Letters, 108(5), Article 051101. https://doi.org/10.1103/PhysRevLett.108.051101

Starting from the most general scalar-tensor theory with second order field equations in four dimensions, we establish the unique action that will allow for the existence of a consistent self-tuning mechanism on FLRW backgrounds, and show how it can... Read More about General second-order scalar-tensor theory and self-tuning.

Evolution and stability of cosmic string loops with Y-junctions (2009)
Journal Article
Bevis, N., Copeland, E. J., Martin, P.-Y., Niz, G., Pourtsidou, A., Saffin, P. M., & Steer, D. (2009). Evolution and stability of cosmic string loops with Y-junctions. Physical Review D, 80(12), https://doi.org/10.1103/PhysRevD.80.125030

We study the evolution of non-periodic cosmic string loops containing Y-junctions, such as may form during the evolution of a network of (p,q) cosmic superstrings. We set up and solve the Nambu-Goto equations of motion for a loop with junctions, focu... Read More about Evolution and stability of cosmic string loops with Y-junctions.

Cosmological constraints on f(G) dark energy models (2009)
Journal Article
Zhou, S.-Y., Copeland, E. J., & Saffin, P. M. (2009). Cosmological constraints on f(G) dark energy models. Journal of Cosmology and Astroparticle Physics, 2009(7), https://doi.org/10.1088/1475-7516/2009/07/009

Modified gravity theories with the Gauss-Bonnet term G=R2−4RμνRμν+RμνρσRμνρσ have recently gained a lot of attention as a possible explanation of dark energy. We perform a thorough phase space analysis on the so-called f(G) models, where f(G) is some... Read More about Cosmological constraints on f(G) dark energy models.

No resonant tunneling in standard scalar quantum field theory (2008)
Journal Article
Copeland, E. J., Padilla, A., & Saffin, P. M. (2008). No resonant tunneling in standard scalar quantum field theory. Journal of High Energy Physics, 2008(1), https://doi.org/10.1088/1126-6708/2008/01/066

We investigate the nature of resonant tunneling in Quantum Field Theory. Following the pioneering work of Banks, Bender and Wu, we describe quantum field theory in terms of infinite dimensional quantum mechanics and utilize the ``Most probable escape... Read More about No resonant tunneling in standard scalar quantum field theory.