Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Classical tests for Weyl gravity: deflection of light and time delay   Weyl gravity has been advanced in the recent past as an alternative to
General Relativity (GR). The theory has had some success in fitting galactic
rotation curves without the need for copious amounts of dark matter. To check
the viability of Weyl gravity, we propose two additional classical tests of the
theory: the deflection of light and time delay in the exterior of a static
spherically symmetric source. The result for the deflection of light is
remarkably simple: besides the usual positive (attractive) Einstein deflection
of $4GM/r_{0}$ we obtain an extra deflection term of $-\gamma r_{0}$ where
$\gamma$ is a constant and $r_0$ is the radius of closest approach. With a
negative $\gamma$, the extra term can increase the deflection on large distance
scales (galactic or greater) and therefore imitate the effect of dark matter.
Notably, the negative sign required for $\gamma$ is opposite to the sign of
$\gamma$ used to fit galactic rotation curves. The experimental constraints
show explicitly that the magnitude of $\gamma$ is of the order of the inverse
Hubble length something already noted by Mannheim and Kazanas as an interesting
numerical coincidence in the fitting of galactic rotation curves.

31
The categories of this paper are: ao-sci
1
The categories of this paper are: cs
25
The categories of this paper are: patt-sol
18
The categories of this paper are: econ
7
The categories of this paper are: hep-th
37
The categories of this paper are: supr-con
12
The categories of this paper are: nucl-th
0
The categories of this paper are: hep-ph
19
The categories of this paper are: eess
23
The categories of this paper are: solv-int
4
The categories of this paper are: cond-mat
3
The categories of this paper are: physics
32
The categories of this paper are: atom-ph
26
The categories of this paper are: bayes-an
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The categories of this paper are: adap-org
27
The categories of this paper are: comp-gas