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Implications of Some Static Spherically Symmetric Graviton-Dilaton Solutions in Brans-Dicke and Low Energy String Theory

S. Kalyana Rama
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Abstract

Analysing the static, spherically symmetric graviton-dilaton solutions in low energy string and Brans-Dicke theory, we find the following. For a charge neutral point star, these theories cannot predict non trivial PPN parameters, $β$ and $γ$, without introducing naked singularities. We then couple a cosmological constant $Λ$ as in low energy string theory. We find that only in low energy string theory, a non zero $Λ$ leads to a curvature singularity, which is much worse than a naked singularity. Requiring its absence upto a distance $r_*$ implies a bound $| Λ| < 10^{- 102} (\frac{r_*}{\rm pc})^{- 2}$ in natural units. If $r_* \simeq 1 {\rm Mpc}$ then $| Λ| < 10^{- 114}$ and, if $r_* \simeq 10^{28} {\rm cm}$ then $| Λ| < 10^{- 122}$ in natural units.

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S. Kalyana Rama. 1995-05-24. Implications of Some Static Spherically Symmetric Graviton-Dilaton Solutions in Brans-Dicke and Low Energy String Theory. https://arxiv.org/abs/hep-th/9505151

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