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Cosmological Variation of the Fine Structure Constant from an Ultra-Light Scalar Field: The Effects of Mass | | Carl L. Gardner
; | | Date: |
6 May 2003 | | Journal: | Phys.Rev. D68 (2003) 043513 | | Subject: | astro-ph hep-ph | | Abstract: | Cosmological variation of the fine structure constant $alpha$ due to the evolution of a spatially homogeneous ultra-light scalar field ($m sim H_0$) during the matter and $Lambda$ dominated eras is analyzed. Agreement of $Delta alpha/alpha$ with the value suggested by recent observations of quasar absorption lines is obtained by adjusting a single parameter, the coupling of the scalar field to matter. Asymptotically $alpha(t)$ in this model goes to a constant value $ar{alpha} approx alpha_0$ in the early radiation and the late $Lambda$ dominated eras. The coupling of the scalar field to (nonrelativistic) matter drives $alpha$ slightly away from $ar{alpha}$ in the epochs when the density of matter is important. Simultaneous agreement with the more restrictive bounds on the variation $|Delta alpha/alpha|$ from the Oklo natural fission reactor and from meteorite samples can be achieved if the mass of the scalar field is on the order of 0.5--0.6 $H_Lambda$, where $H_Lambda = Omega_Lambda^{1/2} H_0$. Depending on the scalar field mass, $alpha$ may be slightly smaller or larger than $alpha_0$ at the times of big bang nucleosynthesis, the emission of the cosmic microwave background, the formation of early solar system meteorites, and the Oklo reactor. The effects on the evolution of $alpha$ due to nonzero mass for the scalar field are emphasized. An order of magnitude improvement in the laboratory technique could lead to a detection of $(dot{alpha}/alpha)_0$. | | Source: | arXiv, astro-ph/0305080 | | Services: | Forum | Review | PDF | Favorites | |
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