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Note added in proof

Recent work by Damour, Piazza and Veneziano (2002a, 2002b) suggests that the universality of free fall (hence the equivalence principle) might be violated near eta=Deltaa/a~10-12. The prediction refers to pairs of test masses made of Cu and Be or Pt and Ti. The present experimental limit for Cu and Be is eta(Be,Cu)=(-1.9±2.5)·10-12 (Su et al., 1994). In Baeßler et al. (1999) the differential acceleration between test masses in the gravitational field of the Sun (a~-0.6 cm s-2) has a 1sigma statistical uncertainty Deltaa=5.6·10-13 cm s-2, hence Deltaa/a~10-12. However, since this experiment compares accelerations of "earth's core" and "moon/mantle" like test bodies, the composition-dependent acceleration DeltaaCD of the Earth and Moon towards the Sun is smaller than Deltaa because only a fraction of their mass is contained in their cores and mantles. The authors conclude that DeltaaCD/a=(+0.1±2.7±1.7)·10-13.

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