Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Einstein-aether theory, violation of Lorentz invariance, and
  metric-affine gravity   We show that the Einstein-aether theory of Jacobson and Mattingly (J&M) can
be understood in the framework of the metric-affine (gauge theory of) gravity
(MAG). We achieve this by relating the aether vector field of J&M to certain
post-Riemannian nonmetricity pieces contained in an independent linear
connection of spacetime. Then, for the aether, a corresponding geometrical
curvature-square Lagrangian with a massive piece can be formulated
straightforwardly. We find an exact spherically symmetric solution of our
model.

34
The categories of this paper are: chem-ph
6
The categories of this paper are: astro-ph
17
The categories of this paper are: q-fin
9
The categories of this paper are: nlin
36
The categories of this paper are: cmp-lg
25
The categories of this paper are: patt-sol
22
The categories of this paper are: chao-dyn
24
The categories of this paper are: dg-ga
18
The categories of this paper are: econ
14
The categories of this paper are: math-ph
29
The categories of this paper are: funct-an
15
The categories of this paper are: nucl-ex
13
The categories of this paper are: quant-ph
8
The categories of this paper are: hep-ex
10
The categories of this paper are: q-bio
28
The categories of this paper are: alg-geom