Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Modified Palatini action that gives the Einstein-Maxwell theory   The actions for bosonic fields typically contain terms quadratic in the
derivatives of the fields. This is not the case in the Palatini approach to
general relativity. The action does not contain any derivatives of the metric
and it only contains terms linear in the derivatives of the connection. In
general relativity the covariant derivative of the metric vanishes, so it is
not possible to include such terms in the action. However, in more general
theories this is not the case.
  In this paper I consider an action which is quadratic in the derivatives of
the metric and connection and show that it leads to the coupled
Einstein-Maxwell theory or the coupled Einstein-Proca theory with the
antisymmetric part of the Ricci tensor playing the role of the electromagnetic
field strength.

23
The categories of this paper are: solv-int
31
The categories of this paper are: ao-sci
24
The categories of this paper are: dg-ga
25
The categories of this paper are: patt-sol
13
The categories of this paper are: quant-ph
33
The categories of this paper are: plasm-ph
32
The categories of this paper are: atom-ph
7
The categories of this paper are: hep-th
36
The categories of this paper are: cmp-lg
22
The categories of this paper are: chao-dyn
28
The categories of this paper are: alg-geom
37
The categories of this paper are: supr-con
29
The categories of this paper are: funct-an
14
The categories of this paper are: math-ph
18
The categories of this paper are: econ
30
The categories of this paper are: q-alg