Research Repository

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Fifth forces, Higgs portals and broken scale invariance (2018)
Journal Article
Burrage, C., Copeland, E. J., Millington, P., & Spannowsky, M. (2018). Fifth forces, Higgs portals and broken scale invariance. Journal of Cosmology and Astroparticle Physics, 2018(11), 1-31. doi:10.1088/1475-7516/2018/11/036

We study the relationship between the strength of fifth forces and the origin of scale breaking in the Standard Model (SM) of particle physics. We start with a light scalar field that is conformally coupled to a toy SM matter sector through a Weyl re... Read More

Stellar kinematics from the symmetron fifth force in the Milky Way disk (2018)
Journal Article
O’Hare, C. A., & Burrage, C. (2018). Stellar kinematics from the symmetron fifth force in the Milky Way disk. Physical Review D, 98(6), doi:10.1103/physrevd.98.064019

It has been shown that the presence of nonminimally coupled scalar fields giving rise to a fifth force can noticeably alter dynamics on galactic scales. Such a fifth force must be screened in the Solar System but if unscreened it can have similar obs... Read More

The shape dependence of chameleon screening (2018)
Journal Article
Burrage, C., Copeland, E. J., Moss, A., & Stevenson, J. A. (2018). The shape dependence of chameleon screening. Journal of Cosmology and Astroparticle Physics, 2018(1), doi:10.1088/1475-7516/2018/01/056. ISSN 1475-7516

Chameleon scalar fields can screen their associated fifth forces from detection by changing their mass with the local density. These models are an archetypal example of a screening mechanism, and have become an important target for both cosmological... Read More

Beyond the growth rate of cosmic structure: testing modified gravity models with an extra degree of freedom (2017)
Journal Article
Burrage, C., Parkinson, D., & Seery, D. (2017). Beyond the growth rate of cosmic structure: testing modified gravity models with an extra degree of freedom. Physical Review D, 96(4), doi:10.1103/PhysRevD.96.043509. ISSN 2470-0010

In ‘modified’ gravity the observed acceleration of the universe is explained by changing the gravitational force law or the number of degrees of freedom in the gravitational sector. Both possibilities can be tested by measurements of cosmological str... Read More

Radial acceleration relation from symmetron fifth forces (2017)
Journal Article
Burrage, C., Copeland, E. J., & Millington, P. (2017). Radial acceleration relation from symmetron fifth forces. Physical Review D, D95(6), doi:10.1103/PhysRevD.95.064050. ISSN 2470-0010

We show that the radial acceleration relation for rotationally supported galaxies may be explained, in the absence of cold dark matter, by a nonminimally coupled scalar field, whose fifth forces are partially screened on galactic scales by the symmet... Read More

Constraining symmetron fields with atom interferometry (2016)
Journal Article
Burrage, C., Kuribayashi-Coleman, A., Stevenson, J., & Thrussell, B. (2016). Constraining symmetron fields with atom interferometry. Journal of Cosmology and Astroparticle Physics, 2016, doi:10.1088/1475-7516/2016/12/041. ISSN 1475-7516

We apply the new constraints from atom-interferometry searches for screening mechanisms to the symmetron model, finding that these experiments exclude a previously unexplored region of the parameter space. We discuss the possibility of networks of do... Read More

A compendium of chameleon constraints (2016)
Journal Article
Burrage, C., & Sakstein, J. (2016). A compendium of chameleon constraints. Journal of Cosmology and Astroparticle Physics, 2016(11), doi:10.1088/1475-7516/2016/11/045. ISSN 1475-7516

The chameleon model is a scalar field theory with a screening mechanism that explains how a cosmologically relevant light scalar can avoid the constraints of intra-solar-system searches for fifth-forces. The chameleon is a popular dark energy candida... Read More

Radiative screening of fifth forces (2016)
Journal Article
Burrage, C., Copeland, E. J., & Millington, P. (2016). Radiative screening of fifth forces. Physical Review Letters, 117(21), doi:10.1103/PhysRevLett.117.211102. ISSN 0031-9007

We describe a symmetron model in which the screening of fifth forces arises at the one-loop level through the Coleman-Weinberg mechanism of spontaneous symmetry breaking. We show that such a theory can avoid current constraints on the existence of fi... Read More

LHC signatures of scalar dark energy (2016)
Journal Article
Burrage, C., Brax, P., Englert, C., & Spannowsky, M. (2016). LHC signatures of scalar dark energy. Physical Review D - Particles, Fields, Gravitation and Cosmology, 94, doi:10.1103/PhysRevD.94.084054. ISSN 1550-7998

Scalar dark energy fields that couple to the standard model can give rise to observable signatures at the LHC. In this work, we show that tt¯+missing energy and monojet searches are suitable probes in the limit where the dark energy scalar is stable... Read More

A proposed experimental search for chameleons using asymmetric parallel plates (2016)
Journal Article
Burrage, C., Copeland, E. J., & Stevenson, J. A. (2016). A proposed experimental search for chameleons using asymmetric parallel plates. Journal of Cosmology and Astroparticle Physics, 2016(8), doi:10.1088/1475-7516/2016/08/070. ISSN 1475-7516

Light scalar fields coupled to matter are a common consequence of theories of dark energy and attempts to solve the cosmological constant problem. The chameleon screening mechanism is commonly invoked in order to suppress the fifth forces mediated by... Read More

Disformal transformations on the CMB (2016)
Journal Article
Burrage, C., Cespedes, S., & Davis, A. (2016). Disformal transformations on the CMB. Journal of Cosmology and Astroparticle Physics, 2016, doi:10.1088/1475-7516/2016/08/024. ISSN 1475-7516

In this work we study the role of disformal transformation on cosmological backgrounds and its relation to the speed of sound for tensor modes. A speed different from one for tensor modes can arise in several contexts, such as Galileons theories or m... Read More

Vacuum Cherenkov radiation and bremsstrahlung from disformal couplings (2016)
Journal Article
van de Bruck, C., Burrage, C., & Morrice, J. (2016). Vacuum Cherenkov radiation and bremsstrahlung from disformal couplings. Journal of Cosmology and Astroparticle Physics, 2016(8), doi:10.1088/1475-7516/2016/08/003. ISSN 1475-7516

The simplest way to modify gravity is to extend the gravitational sector to include an additional scalar degree of freedom. The most general metric that can be built in such a theory includes disformal terms, so that standard model fields move on a m... Read More

The speed of Galileon gravity (2016)
Journal Article
Brax, P., Burrage, C., & Davis, A. (2016). The speed of Galileon gravity. Journal of Cosmology and Astroparticle Physics, 2016(3), doi:10.1088/1475-7516/2016/03/004. ISSN 1475-7516

We analyse the speed of gravitational waves in coupled Galileon models with an equation of state ωphgr=−1 now and a ghost-free Minkowski limit. We find that the gravitational waves propagate much faster than the speed of light unless these models are... Read More

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), doi:10.1080/00107514.2015.1060058. ISSN 0010-7514

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

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, 1503(3), doi:10.1088/1475-7516/2015/03/042. ISSN 1475-7516

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 we show that individual atoms are too small to scr... Read More