Jason Steffen, Fermilab
Results of the GammeV Axion-like Particle Search
March 05, 2008

I report on the results of the GammeV experiment---a
light-shining-though-a-wall search for axion-like particles.  This
experiment was motivated to study the reported signal of the PVLAS
experiment which was indicative of a new axion-like particle with a mass
near 1meV---a possible dark matter canditate.  Using spare parts from the
Tevatron particle accelerator and a novel, variable-baseline experimental
approach we were able to probe the PVLAS region of interest with a high
sensitivity.  Our results exclude, at greater than 5-sigma, the particle
interpretation of the PVLAS signal for both scalar and pseudoscalar
particles.  I also report some preliminary results from the GammeV
chameleon particle search.