Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Schr\"odinger connection with selfdual nonmetricity vector in 2+1
  dimensions   We present a three-dimensional metric affine theory of gravity whose field
equations lead to a connection introduced by Schr\"odinger many decades ago.
Although involving nonmetricity, the Schr\"odinger connection preserves the
length of vectors under parallel transport, and appears thus to be more
physical than the one proposed by Weyl. By considering solutions with constant
scalar curvature, we obtain a self-duality relation for the nonmetricity vector
which implies a Proca equation that may also be interpreted in terms of
inhomogeneous Maxwell equations emerging from affine geometry.

31
The categories of this paper are: ao-sci
22
The categories of this paper are: chao-dyn
29
The categories of this paper are: funct-an
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
4
The categories of this paper are: cond-mat
36
The categories of this paper are: cmp-lg
25
The categories of this paper are: patt-sol
17
The categories of this paper are: q-fin
30
The categories of this paper are: q-alg
27
The categories of this paper are: comp-gas
34
The categories of this paper are: chem-ph
11
The categories of this paper are: hep-lat
12
The categories of this paper are: nucl-th
33
The categories of this paper are: plasm-ph