The string dilation and a least coupling principle
Abstract
It is pointed out that stringloop modifications of the lowenergy 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 gravitondilatonmatter 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 nonzero, 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:

Nuclear Physics B
 Pub Date:
 July 1994
 DOI:
 10.1016/05503213(94)901430
 arXiv:
 arXiv:hepth/9401069
 Bibcode:
 1994NuPhB.423..532D
 Keywords:

 High Energy Physics  Theory
 EPrint:
 23 pages