Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: G\"{o}del-type solutions in hybrid metric-Palatini gravity   In this paper, the hybrid metric-Palatini gravity is an approach to modified
gravity in which is added to the usual Einstein-Hilbert action a supplementary
term containing a Palatini-type correction of the form $f({\cal R},T)$. Here,
${\cal R}$ is the Palatini curvature scalar, which is constructed from an
independent connection and $T$ is the trace of the energy-momentum tensor. This
theory describes a non-minimal coupling between matter and geometry. The
modified Einstein field equations in this hybrid metric-Palatini approach are
obtained. Then, it is investigated whether this modified theory of gravity and
its field equations allow G\"{o}del-type solutions, which essentially lead to
violation of causality. Considering physically well-motivated matter sources,
causal and non-causal solutions are explored.

14
The categories of this paper are: math-ph
17
The categories of this paper are: q-fin
16
The categories of this paper are: stat
36
The categories of this paper are: cmp-lg
35
The categories of this paper are: mtrl-th
2
The categories of this paper are: math
11
The categories of this paper are: hep-lat
10
The categories of this paper are: q-bio
9
The categories of this paper are: nlin
21
The categories of this paper are: adap-org
12
The categories of this paper are: nucl-th
25
The categories of this paper are: patt-sol
3
The categories of this paper are: physics
24
The categories of this paper are: dg-ga
0
The categories of this paper are: hep-ph
28
The categories of this paper are: alg-geom