1306.4871 (Christopher Frye et al.)

String Theory has no Isotropic Solution for the Modified Einstein's
Equations without the Dilaton    [PDF]

Christopher Frye, Costas Efthimiou

We investigate the modification to Einstein's vacuum field equations which is imposed by string theory when the dilaton field is ignored. Including the cosmological constant in all calculations, we prove that such a theory of gravity admits no static isotropic solution. We then show that any isotropic solution of the equations in question must necessarily be static, therefore proving that no isotropic solution exists for this stringy modification to gravity.

View original: http://arxiv.org/abs/1306.4871