Imperial College London

Claudia de Rham

Faculty of Natural SciencesDepartment of Physics

Professor of Theoretical Physics
 
 
 
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Contact

 

+44 (0)20 7594 7841c.de-rham CV

 
 
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Location

 

506Blackett LaboratorySouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

78 results found

Kobayashi T, Shiromizu T, de Rham C, 2008, Curvature corrections to the low energy effective theory in 6D regularized braneworlds, PHYSICAL REVIEW D, Vol: 77, ISSN: 2470-0010

JOURNAL ARTICLE

de Rham C, Hofmann S, Khoury J, Tolley AJet al., 2008, Cascading gravity and degravitation, JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS, ISSN: 1475-7516

JOURNAL ARTICLE

de Rham C, 2008, The effective field theory of codimension-two branes, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479

JOURNAL ARTICLE

de Rham C, Watson S, 2007, Living on a dS brane: effects of KK modes on inflation, CLASSICAL AND QUANTUM GRAVITY, Vol: 24, Pages: 4219-4234, ISSN: 0264-9381

JOURNAL ARTICLE

Burgess CP, de Rham C, Hoover D, Mason D, Tolley AJet al., 2007, Kicking the rugby ball: perturbations of 6D gauged chiral supergravity, JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS, ISSN: 1475-7516

JOURNAL ARTICLE

de Rham C, 2007, Classical renormalization of codimension-two brane couplings, 13th International Symposium on Particles, Strings and Cosmology (PASCOS 2007), Publisher: AMER INST PHYSICS, Pages: 309-312, ISSN: 0094-243X

CONFERENCE PAPER

Tolley AJ, Burgess CP, de Rham C, Hoover Det al., 2006, Scaling solutions to 6D gauged chiral supergravity, NEW JOURNAL OF PHYSICS, Vol: 8, ISSN: 1367-2630

JOURNAL ARTICLE

de Rham C, Tolley AJ, 2006, Mimicking Lambda with a spin-two ghost condensate, JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS, ISSN: 1475-7516

JOURNAL ARTICLE

Shiromizu T, Fujii S, de Rham C, Yoshino Het al., 2006, High-energy effective theory for orbifold branes, PHYSICAL REVIEW D, Vol: 73, ISSN: 1550-7998

JOURNAL ARTICLE

de Rham C, Tolley AJ, 2006, Gravitational waves in a codimension two braneworld, JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS, ISSN: 1475-7516

JOURNAL ARTICLE

de Rham C, Fujii S, Shiromizu T, Yoshino Het al., 2005, High-energy effective theory for a bulk brane, PHYSICAL REVIEW D, Vol: 72, ISSN: 2470-0010

JOURNAL ARTICLE

de Rham C, Webster S, 2005, High-energy effective theory for matter on close Randall-Sundrum branes, PHYSICAL REVIEW D, Vol: 72, ISSN: 2470-0010

JOURNAL ARTICLE

de Rham C, Webster S, 2005, High-energy theory for close Randall-Sundrum branes, PHYSICAL REVIEW D, Vol: 71, ISSN: 2470-0010

JOURNAL ARTICLE

de Rham C, 2005, Beyond the low energy approximation in braneworld cosmology, PHYSICAL REVIEW D, Vol: 71, ISSN: 2470-0010

JOURNAL ARTICLE

Jain B, Joyce A, Thompson R, Upadhye A, Battat J, Brax P, Davis A-C, Rham CD, Dodelson S, Erickcek A, Gabadadze G, Hu W, Hui L, Huterer D, Kamionkowski M, Khoury J, Koyama K, Li B, Linder E, Schmidt F, Scoccimarro R, Starkman G, Stubbs C, Takada M, Tolley A, Trodden M, Uzan J-P, Vikram V, Weltman A, Wyman M, Zaritsky D, Zhao Get al., Novel Probes of Gravity and Dark Energy

The discovery of cosmic acceleration has stimulated theorists to considerdark energy or modifications to Einstein's General Relativity as possibleexplanations. The last decade has seen advances in theories that go beyondsmooth dark energy -- modified gravity and interactions of dark energy. Whilethe theoretical terrain is being actively explored, the generic presence offifth forces and dark sector couplings suggests a set of distinct observationalsignatures. This report focuses on observations that differ from theconventional probes that map the expansion history or large-scale structure.Examples of such novel probes are: detection of scalar fields via labexperiments, tests of modified gravity using stars and galaxies in the nearbyuniverse, comparison of lensing and dynamical masses of galaxies and clusters,and the measurements of fundamental constants at high redshift. Theobservational expertise involved is very broad as it spans laboratoryexperiments, high resolution astronomical imaging and spectroscopy and radioobservations. In the coming decade, searches for these effects have thepotential for discovering fundamental new physics. We discuss how the searchescan be carried out using experiments that are already under way or with modestadaptations of existing telescopes or planned experiments. The accompanyingpaper on the Growth of Cosmic Structure describes complementary tests ofgravity with observations of large-scale structure.

JOURNAL ARTICLE

Rham CD, Gabadadze G, Tolley AJ, Comments on (super)luminality

Recently, in an interesting work arXiv:1106.3972 a solution of the equationsof motion of massive gravity was discussed, and it was shown that one of thefluctuations on that solution is superluminal. It was also stated that thisrules out massive gravity. Here we find that the solution itself is ratherunphysical. For this we show that there is another mode on the same backgroundwhich grows and overcomes the background in an arbitrarily short period oftime, that can be excited by a negligible cost in energy. This solution istriggered by the parameter governing the superluminality. Furthermore, we alsoshow that the solution, if viewed as a perfect fluid, has no rest frame, orthat the Lorentz transformation that is needed to boost to the rest frame issuperluminal itself. The stress-tensor of this fluid has complex eigenvalues,and could not be obtained from any physically sensible matter. Moreover, forthe same setup we find another background solution, fluctuations of which areall stable and subluminal. Based on these results, we conclude that thesuperluminality found in arXiv:1106.3972 is an artifact of using aninappropriate background, nevertheless, this solution represents an instructiveexample for understanding massive gravity. For instance, on this background theBoulware-Deser ghost is absent, even though this may naively appear not to bethe case.

JOURNAL ARTICLE

Rham CD, Shiromizu T, Tolley AJ, Weaker Gravity at Submillimetre Scales in Braneworld Models

Braneworld models typically predict gravity to grow stronger at shortdistances. In this paper, we consider braneworlds with two types of additionalcurvature couplings, a Gauss-Bonnet term in the bulk, and an Einstein-Hilbert(EH) term on the brane. In the regime where these terms are dominant over thebulk EH term, linearized gravity becomes weaker at short distances on thebrane. In both models, the weakening of gravity is tied to the presence ofghosts in the graviton mass spectrum. We find that the ordinary coupling ofmatter to gravity is recovered at low energies/long wavelengths on the brane.We give some implications for cosmology and show its compatibility withobservations. We also discuss the stability of compact stars.

JOURNAL ARTICLE

Rham CD, Heisenberg L, Tolley AJ, Spin-2 and the Weak Gravity Conjecture

Recently, it has been argued that application of the Weak Gravity Conjecture(WGC) to spin-2 fields implies a universal upper bound on the cutoff of theeffective theory for a single spin-2 field. We point out here that thesearguments are largely spurious, because of the absence of states carryingspin-2 St\"uckelberg $U(1)$ charge, and because of incorrect scalingassumptions. Known examples such as Kaluza-Klein theory that respect the usualWGC do so because of the existence of a genuine $U(1)$ field under which statesare charged, as in the case of the St\"uckelberg formulation of spin-1theories, for which there is an unambiguously defined $U(1)$ charge. Theoriesof bigravity naturally satisfy a naive formulation of the WGC, $M_W < M_{\rmPl}$, since the force of the massless graviton is always weaker than themassive spin-2 modes. It also follows that theories of massive gravitytrivially satisfies this form of the WGC. We also point out that theidentification of a massive spin-2 state in a truncated higher derivativetheory, such as Einstein-Weyl-square or its supergravity extension, bears norelationship with massive spin-2 states in the UV completion, contrary toprevious statements in the literature.

WORKING PAPER

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