857 citations · 4.9k across the 68 of their papers we have counts for
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Adiabatic and entropy perturbations with interacting fluids and fields
Karim A. Malik, David Wands
We develop a gauge-invariant formalism for the study of density perturbations in a Friedmann-Robertson-Walker universe with multiple interacting fluids and/or scalar fields. We sho…
A general proof of the conservation of the curvature perturbation
David H. Lyth, Karim A. Malik, Misao Sasaki
Without invoking a perturbative expansion, we define the cosmological curvature perturbation, and consider its behaviour assuming that the universe is smooth over a sufficiently la…
A new calculation of the mass fraction of primordial black holes
Anne M. Green, Andrew R. Liddle, Karim A. Malik +1
We revisit the calculation of the abundance of primordial black holes (PBHs) formed from primordial density perturbations, using a formation criterion derived by Shibata and Sasaki…