Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Gravity tests and the Pioneer anomaly   Experimental tests of gravity performed in the solar system show a good
agreement with general relativity. The latter is however challenged by the
Pioneer anomaly which might be pointing at some modification of gravity law at
ranges of the order of the size of the solar system. We introduce a metric
extension of general relativity which, while preserving the equivalence
principle, modifies the coupling between curvature and stress tensors and,
therefore, the metric solution in the solar system. The ``post-Einsteinian
extension'' replaces Newton gravitation constant by two running coupling
constants, which depend on the scale and differ in the sectors of traceless and
traced tensors, so that the metric solution is characterized by two gravitation
potentials. The extended theory has the capability to preserve compatibility
with gravity tests while accounting for the Pioneer anomaly. It can also be
tested by new experiments or, maybe, by having a new look at data of already
performed experiments.

28
The categories of this paper are: alg-geom
4
The categories of this paper are: cond-mat
24
The categories of this paper are: dg-ga
9
The categories of this paper are: nlin
18
The categories of this paper are: econ
25
The categories of this paper are: patt-sol
10
The categories of this paper are: q-bio
3
The categories of this paper are: physics
2
The categories of this paper are: math
34
The categories of this paper are: chem-ph
20
The categories of this paper are: acc-phys
6
The categories of this paper are: astro-ph
19
The categories of this paper are: eess
32
The categories of this paper are: atom-ph
17
The categories of this paper are: q-fin
35
The categories of this paper are: mtrl-th