Abstract
We compute the parametrized post-Newtonian (PPN), , for scalar tensor gravity theory when the action functional for the scalar field is a nonstandard one, namely, the Dirac-Born-Infeld type action, used in the literature for a tachyon field. We investigate two different cases (linear and conformal couplings) when the scalar field is nonminimally coupled to gravity via the scalar curvature. We find that the PPN parameter , which measures the amount of space curvature per unit rest mass, becomes a function of the effective mass of the scalar field. Using this PPN parameter, we calculate the time delay for the signal to travel the round-trip distance between a ground-based antenna and a reflector placed in a spacecraft which is produced due to the gravitational field of the Sun. We use this to compare our result with that obtained by the Cassini mission and derive the constraints on the model parameters.
- Received 13 April 2011
DOI:https://doi.org/10.1103/PhysRevD.84.063521
© 2011 American Physical Society