Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: An equivalence principle for scalar forces   The equivalence of inertial and gravitational masses is a defining feature of
general relativity. Here, we clarify the status of the equivalence principle
for interactions mediated by a universally coupled scalar, motivated partly by
recent attempts to modify gravity at cosmological distances. Although a
universal scalar-matter coupling is not mandatory, once postulated, it is
stable against classical and quantum renormalizations in the matter sector. The
coupling strength itself is subject to renormalization of course. The scalar
equivalence principle is violated only for objects for which either the
graviton self-interaction or the scalar self-interaction is important---the
first applies to black holes, while the second type of violation is avoided if
the scalar is Galilean-symmetric.

29
The categories of this paper are: funct-an
1
The categories of this paper are: cs
19
The categories of this paper are: eess
20
The categories of this paper are: acc-phys
27
The categories of this paper are: comp-gas
21
The categories of this paper are: adap-org
24
The categories of this paper are: dg-ga
12
The categories of this paper are: nucl-th
32
The categories of this paper are: atom-ph
9
The categories of this paper are: nlin
28
The categories of this paper are: alg-geom
15
The categories of this paper are: nucl-ex
35
The categories of this paper are: mtrl-th
33
The categories of this paper are: plasm-ph
10
The categories of this paper are: q-bio
22
The categories of this paper are: chao-dyn