Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Breaking Diffeomorphism Invariance and Tests for the Emergence of
  Gravity   If general relativity is an emergent phenomenon, there may be small
violations of diffeomorphism invariance. We propose a phenomenology of
perturbatively small violations of general relativity by the inclusion of terms
which break general covariance. These can be tested by matching to the
Parametrized Post Newtonian (PPN) formalism. The most sensitive tests involve
pulsar timing and provide an extremely strong bound, with a dimensionless
constraint of order 10^{-20} relative to gravitational strength.

21
The categories of this paper are: adap-org
2
The categories of this paper are: math
17
The categories of this paper are: q-fin
3
The categories of this paper are: physics
14
The categories of this paper are: math-ph
29
The categories of this paper are: funct-an
6
The categories of this paper are: astro-ph
33
The categories of this paper are: plasm-ph
18
The categories of this paper are: econ
4
The categories of this paper are: cond-mat
34
The categories of this paper are: chem-ph
8
The categories of this paper are: hep-ex
20
The categories of this paper are: acc-phys
13
The categories of this paper are: quant-ph
10
The categories of this paper are: q-bio
25
The categories of this paper are: patt-sol