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New limits on the violation of the Strong Equivalence Principle in strong field regimes

Norbert Wex
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Abstract

The Strong Equivalence Principle (SEP) demands, besides the validity of the Einstein Equivalence Principle, that all self-gravitating bodies feel the same acceleration in an external gravitational field. It has been found that metric theories of gravity other that than general relativity typically predict a violation of the SEP. In case of the Earth-Moon system (weak field system) this violation is called the Nordtvedt effect. It has been shown by Damour and Schäfer, that small-eccentricity long-orbital-period binary pulsars with a white dwarf companion provide excellent conditions to test the SEP in strong field regimes. Based on newly discovered binary pulsars this paper investigates a possible violation of the SEP in strong field regimes. New limits with an improved confidence level are presented. The results of this paper lead to constrains on the combination $ε/2-ζ$ of the only two (post)$^2$-Newtonian parameters $ε$ and $ζ$ that arise from the (post)$^2$-Newtonian approximation of the tensor-multi-scalar theory of Damour and Esposito-Far{è}se.

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Norbert Wex. 1996-06-29. New limits on the violation of the Strong Equivalence Principle in strong field regimes. https://arxiv.org/abs/gr-qc/9511017

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