Dark Matter, Time-varying G and the Dilaton
نویسندگان
چکیده
The value of the Jordan-Brans-Dicke coupling parameter ! is at present much more tightly bounded below by radar time delay experiments than it is by the predicted time variation of Newton's constant G. We point out the possibility of having a Jordan-Brans-Dicke-type scalar (i.e. a scale-free massless scalar eld or \dilaton") couple with diierent strengths to visible and to conjectured \dark" matter. This would allow a larger time variation of G (and a small value of ! for dark matter) while ! is still large for visible matter. _ G estimations (e.g. from the binary pulsar) may thus provide nontrivial bounds on the coupling of the dilaton to dark matter.
منابع مشابه
Quintessence as a runaway dilaton
We consider a late-time cosmological model based on a recent proposal that the infinite-bare-coupling limit of superstring/M-theory exists and has good phenomenological properties, including a vanishing cosmological constant, and a massless, decoupled dilaton. As it runs away to +∞, the dilaton can play the role of the quintessence field recently advocated to drive the late-time accelerated exp...
متن کاملViolations of the equivalence principle in a dilaton - runaway scenario
We explore a version of the cosmological dilaton-fixing and decoupling mechanism in which the dilaton dependence of the low-energy effective action is extremized for infinitely large values of the bare string coupling gs 5ef. We study the efficiency with which the dilaton f runs away toward its ‘‘fixed point’’ at infinity during a primordial inflationary stage, and thereby approximately decoupl...
متن کاملStatefinder Diagnostic for Dilaton Dark Energy
Statefinder diagnostic is a useful method which can differ one dark energy model from the others. The Statefinder pair {r, s} is algebraically related to the equation of state of dark energy and its first time derivative. We apply in this paper this method to the dilaton dark energy model based on Weyl-Scaled induced gravitational theory. We investigate the effect of the coupling between matter...
متن کاملDilaton-assisted dark matter.
A dilaton could be the dominant messenger between standard model fields and dark matter. The measured dark matter relic abundance relates the dark matter mass and spin to the conformal breaking scale. The dark matter-nucleon spin-independent cross section is predicted in terms of the dilaton mass. We compute the current constraints on the dilaton from LEP and Tevatron experiments, and the gamma...
متن کاملDilatonic Dark Matter ∗ – A New Paradigm –
We study the possibility that the dilaton plays the role of the dark matter of the universe. We find that the condition for the dilaton to be the dark matter of the universe strongly restricts its mass to be around 0.5 keV or 270 MeV. For the other mass ranges, the dilaton either undercloses or overcloses the universe. The 0.5 keV dilaton has the free-streaming distance of about 1.4 Mpc and bec...
متن کامل