Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Short Distance Repulsive Gravity as a Consequence of Non Trivial PPN
  Parameters $\beta$ and $\gamma$   We look for a graviton-dilaton theory which can predict non trivial values of
the PPN parameters $\beta$ and/or $\gamma$ for a charge neutral point star,
without any naked singularity. With the potential for dilaton $\phi$ set to
zero, it contains one arbitrary function $\psi(\phi)$. Our requirements impose
certain constraints on $\psi$, which lead to the following generic and model
independent novel results: For a charge neutral point star, the gravitational
force becomes repulsive at distances of the order of, but greater than, the
Schwarzschild radius $r_0$. There is also no horizon for $r > r_0$. These
results suggest that black holes are unlikely to form in a stellar collapse in
this theory.

18
The categories of this paper are: econ
8
The categories of this paper are: hep-ex
31
The categories of this paper are: ao-sci
3
The categories of this paper are: physics
15
The categories of this paper are: nucl-ex
14
The categories of this paper are: math-ph
2
The categories of this paper are: math
19
The categories of this paper are: eess
10
The categories of this paper are: q-bio
16
The categories of this paper are: stat
27
The categories of this paper are: comp-gas
33
The categories of this paper are: plasm-ph
34
The categories of this paper are: chem-ph
20
The categories of this paper are: acc-phys
11
The categories of this paper are: hep-lat
17
The categories of this paper are: q-fin