Outputs (71)

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.

Reducing heterotic M-theory to five dimensional supergravity on a manifold with boundary (2011)
Journal Article
Moss, I. G., Omotani, J. T., & Saffin, P. M. (2011). Reducing heterotic M-theory to five dimensional supergravity on a manifold with boundary. Journal of High Energy Physics, 2011(10), https://doi.org/10.1007/JHEP10%282011%29088

This paper constructs the reduction of heterotic M-theory in eleven dimensions to a supergravity model on a manifold with boundary in five dimensions using a Calabi-Yau three-fold. New results are presented for the boundary terms in the action and fo... Read More about Reducing heterotic M-theory to five dimensional supergravity on a manifold with boundary.

Colliding branes and big crunches (2011)
Journal Article
Omotani, J., Saffin, P. M., & Louko, J. (2011). Colliding branes and big crunches. Physical Review D, 84(6), Article 063526. https://doi.org/10.1103/PhysRevD.84.063526

We examine the global structure of colliding domain walls in AdS spacetime and come to the conclusion that singularities forming from such collisions are of the big-crunch type rather than that of a black brane.

Real-time fermions for baryogenesis simulations (2011)
Journal Article
Saffin, P. M., & Tranberg, A. (2011). Real-time fermions for baryogenesis simulations. Journal of High Energy Physics, 2011(7), https://doi.org/10.1007/JHEP07%282011%29066

We study how to numerically simulate quantum fermions out of thermal equilibrium, in the context of electroweak baryogenesis. We find that by combining the lattice implementation of Aarts and Smit [1] with the "low cost" fermions of Borsanyi and Hind... Read More about Real-time fermions for baryogenesis simulations.

Multi-Galileons, solitons, and Derrick’s theorem (2011)
Journal Article
Padilla, A., Saffin, P. M., & Zhou, S.-Y. (2011). Multi-Galileons, solitons, and Derrick’s theorem. Physical Review D, 83(4), https://doi.org/10.1103/PhysRevD.83.045009

The field theory Galilean symmetry, which was introduced in the context of modified gravity, gives a neat way to construct Lorentz-covariant theories of a scalar field, such that the equations of motion contain at most second-order derivatives. Here... Read More about Multi-Galileons, solitons, and Derrick’s theorem.

Bi-galileon theory II: phenomenology (2011)
Journal Article
Padilla, A., Saffin, P. M., & Zhou, S.-Y. (2011). Bi-galileon theory II: phenomenology. Journal of High Energy Physics, 2011(1), https://doi.org/10.1007/JHEP01%282011%29099

We continue to introduce bi-galileon theory, the generalisation of the single galileon model introduced by Nicolis et al. The theory contains two coupled scalar fields and is described by a Lagrangian that is invariant under Galilean shifts in those... Read More about Bi-galileon theory II: phenomenology.

Bi-galileon theory I: motivation and formulation (2010)
Journal Article
Padilla, A., Saffin, P. M., & Zhou, S.-Y. (2010). Bi-galileon theory I: motivation and formulation. Journal of High Energy Physics, 2010(12), https://doi.org/10.1007/JHEP12%282010%29031

We introduce bi-galileon theory, the generalisation of the single galileon model introduced by Nicolis et al. The theory contains two coupled scalar fields and is described by a Lagrangian that is invariant under Galilean shifts in those fields. This... Read More about Bi-galileon theory I: motivation and formulation.

The gravitational dynamics of warped throats (2010)
Journal Article
Butcher, N. A., & Saffin, P. M. (in press). The gravitational dynamics of warped throats. Journal of High Energy Physics, 2010(6), https://doi.org/10.1007/JHEP06%282010%29044

We investigate the time evolution due to gravitational dynamics of a particular spacetime commonly used in brane-cosmology and string compactifications, namely the Klebanov-Strassler geometry, which is achieved by adding a perturbation to the momentu... Read More about The gravitational dynamics of warped throats.

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.

Strong coupling in Hořava gravity (2009)
Journal Article
Charmousis, C., Niz, G., Padilla, A., & Saffin, P. M. (2009). Strong coupling in Hořava gravity. Journal of High Energy Physics, 2009(8), https://doi.org/10.1088/1126-6708/2009/08/070

By studying perturbations about the vacuum, we show that Horava gravity suffers from two different strong coupling problems, extending all the way into the deep infra-red. The first of these is associated with the principle of detailed balance and ex... Read More about Strong coupling in Hořava gravity.