Search for Cosmic Axions using an Optical Interferometer.pdf

Search for Cosmic Axions using an Optical Interferometer A.C.Melissinos 8 July 7, 2008 0 0 2 l u Abstract J 7 We suggest that a two arm, three mirror, optical cavity can be used to search for cosmic ] “axions” in the mass range 10−8 ma 10−6 eV. The carrier (λ ∼ 1 m) resonates in one h p arm. The signal from axion conversion appears as sidebands on the carrier and is resonant - p in the other arm of the cavity. Given the axion−γ − γ coupling predicted by the current e 3 h theoretical models, and if, as expected, the local axion density ρa = 500 Mev/cm , the search [ can be completed in two months. This technique can be extended to ma ∼ 10−3 eV but with 1 reduced sensitivity. v 2 9 0 1 The existence of light pseudoscalars, so called “axions”, was postulated in the 1980’s 7. [1, 2, 3]. Axions remain an attractive candidate for the cold dark matter of the universe 0 [4, 5]. As a result of their gravitational attraction and very weak interaction with ordinary 8 0 matter, axions are expected to condense into galactic halos. The local axion density is : estimated to exceed their average density by a factor of ∼ 105 [6]. v i Axions couple to two photons through the triangle anomaly and the effective action X density can be written [7] r a L = 1 2 2 1 ∂ 2 1 1 2 E − B + φ − ∇φ − m φ − gE Bφ (1)