3 papers
hep-th2002
Cosmological Brane Perturbations
Karim A. Malik
Two approaches to the study of cosmological perturbations in the brane-world scenario are compared: the first uses the 5D equations directly whereas the second approach projects th…
astro-ph2001
Cosmological Perturbations in an Inflationary Universe
Karim A. Malik
After introducing gauge-invariant cosmological perturbation theory we give an improved set of governing equations for multiple fluids including energy transfer. Having defined adia…
gr-qc1998
Gauge-Invariant Variables on Cosmological Hypersurfaces
Karim A. Malik, David Wands
We show how gauge-invariant cosmological perturbations may be constructed by an unambiguous choice of hypersurface-orthogonal time-like vector field (i.e., time-slicing). This may…