The GammeV suite of experimental searches for axion-like particles (2009)
Steffen, Jason H., Upadhye, Amol
We report on the design and results of the GammeV search for axion-like particles and for chameleon particles. We also discuss plans for an improved experiment to search for chameleon particles, one...
The existence of relativistic stars in f(R) gravity (2009)
We refute recent claims in the literature that stars with relativistically deep potentials cannot exist in $f(R)$ gravity. Numerical examples of stable stars, including relativistic...
Unveiling Chameleons in Tests of Gravitational Inverse-Square Law (2006)
Upadhye, Amol, Gubser, Steven S., Khoury, Justin
Scalar self interactions are known to weaken considerably the current constraints on scalar-mediated fifth forces. We consider a scalar field with a quartic self interaction and gravitation-strength...
Ishak, Mustapha, Upadhye, Amol, Spergel, David N.
If general relativity is the correct theory of physics on large scales, then there is a differential equation that relates the Hubble expansion function, inferred from measurements of angular...
Dynamical dark energy: Current constraints and forecasts (2004)
Upadhye, Amol, Ishak, Mustapha, Steinhardt, Paul J.
We consider how well the dark energy equation of state $w$ as a function of red shift $z$ will be measured using current and anticipated experiments. We use a procedure which takes fair account of...