http://arxiv.org/abs/1507.03081
Refined constraints on chameleon theories are calculated for atom-interferometry experiments, using a numerical approach consisting in solving for a four-region model the static and spherically symmetric Klein-Gordon equation for the chameleon field. By modeling not only the test mass and the vacuum chamber but also its walls and the exterior environment, the method allows to probe new effects on the scalar field profile and the induced acceleration of atoms. In the case of a weakly perturbing test mass, the effect of the wall is to enhance the field profile and to lower the acceleration inside the chamber by up to one order of magnitude. In the thin-shell regime, significant deviations from the analytical estimations are found, even when measurements are realized in the immediate vicinity of the test mass. Close to the vacuum chamber wall, the acceleration becomes negative and potentially measurable. This prediction could be used to discriminate between fifth-force effects and systematic experimental uncertainties, by doing the experiment at several key positions inside the vacuum chamber. The influence of the wall thickness and density is also studied. For the chameleon potential $V(\phi) = \Lambda^{4+\alpha} / \phi^\alpha$ and a coupling function $A(\phi) = \exp(\phi /M)$, one finds $M \gtrsim 7 \times 10^{16}$ GeV, independently of the power-law index. For $V(\phi) = \Lambda^4 (1+ \Lambda/ \phi)$ one finds $M \gtrsim 4 \times 10^{16}$ GeV. Future experiments able to measure an acceleration $a \sim 10^{-11} \mathrm{m/s^2}$ would probe the chameleon parameter space up to the Planck scale. Our method can easily be extended to constrain other models with a screening mechanism, such as symmetron, dilaton and f(R) theories.
S. Schlogel, S. Clesse and A. Fuzfa
Tue, 14 Jul 15
51/64
Comments: 12 pages, 10 figures
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