Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Shift-symmetric $SO(N)$ multi-Galileon   A Poincar\`{e} invariant, local scalar field theory in which the Lagrangian
and the equation of motion contain only up to second-order derivatives of the
fields is called generalized Galileon. The covariant version of it in four
dimensions is called Horndeski theory, and has been vigorously studied in
applications to inflation and dark energy. In this paper, we study a class of
multi-field extensions of the generalized Galileon theory. By imposing shift
and $SO(N)$ symmetries on all the currently known multi-Galileon terms in
general dimensions, we find that the structure of the Lagrangian is uniquely
determined and parameterized by a series of coupling constants. We also study
tensor perturbation in the shift-symmetric $SO(3)$ multi-Galileon theory in
four dimensions. The tensor perturbations can obtain a mass term stemming from
the same symmetry breaking pattern as the solid inflation. We also find that
the shift-symmetric $SO(3)$ multi-Galileon theory gives rise to new cubic
interactions of the tensor modes, suggesting the existence of a new type of
tensor primordial non-Gaussianity.

1
The categories of this paper are: cs
33
The categories of this paper are: plasm-ph
21
The categories of this paper are: adap-org
10
The categories of this paper are: q-bio
11
The categories of this paper are: hep-lat
22
The categories of this paper are: chao-dyn
9
The categories of this paper are: nlin
29
The categories of this paper are: funct-an
34
The categories of this paper are: chem-ph
35
The categories of this paper are: mtrl-th
19
The categories of this paper are: eess
25
The categories of this paper are: patt-sol
16
The categories of this paper are: stat
23
The categories of this paper are: solv-int
0
The categories of this paper are: hep-ph
17
The categories of this paper are: q-fin