The string dilation and a least coupling principle
Abstract
It is pointed out that string-loop modifications of the low-energy matter couplings of the dilation may provide a mechanism for fixing the vacuum expectation value of a massless dilation in a way which is naturally compatible with existing experimental data. Under a certain assumption of universality of the dilation coupling functions, the cosmological evolution of the graviton-dilaton-matter system is shown to drive the dilaton towards values where it decouples from matter (``Least Coupling Principle''). Quantitative estimates are given of the residual strength, at the present cosmological epoch, of the coupling to matter of the dilaton. The existence of a weakly coupled massless dilaton entails a large spectrum of small, but non-zero, observable deviations from general relativity. In particular, our results provide a new motivation for trying to improve by several orders of magnitude the various experimental tests of Einstein's Equivalence Principle (universality of free fall, constancy of the constants, etc.).
- Publication:
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Nuclear Physics B
- Pub Date:
- July 1994
- DOI:
- 10.1016/0550-3213(94)90143-0
- arXiv:
- arXiv:hep-th/9401069
- Bibcode:
- 1994NuPhB.423..532D
- Keywords:
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- High Energy Physics - Theory
- E-Print:
- 23 pages