Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Noether identities in gravity theories with nondynamical backgrounds and
  explicit spacetime symmetry breaking   Gravitational effective field theories with nondynamical backgrounds
explicitly break diffeomorphism and local Lorentz invariance. At the same time,
to maintain observer independence the action describing these theories is
required to be mathematically invariant under general coordinate
transformations and changes of local Lorentz bases. These opposing effects of
having broken spacetime symmetries but invariance under mathematical observer
transformations can result in theoretical inconsistency unless certain
conditions hold. The consistency constraints that must hold originate from
Noether identities associated with the mathematical observer invariances in the
action. These identities are examined in detail and are used to investigate
gravity theories with nondynamical backgrounds, including when a St\"uckelberg
approach is used. Specific examples include gravity theories with fixed scalar
or tensor backgrounds, Einstein-Maxwell theory with a fixed external current,
and massive gravity.

14
The categories of this paper are: math-ph
37
The categories of this paper are: supr-con
24
The categories of this paper are: dg-ga
29
The categories of this paper are: funct-an
35
The categories of this paper are: mtrl-th
8
The categories of this paper are: hep-ex
27
The categories of this paper are: comp-gas
18
The categories of this paper are: econ
19
The categories of this paper are: eess
4
The categories of this paper are: cond-mat
30
The categories of this paper are: q-alg
34
The categories of this paper are: chem-ph
13
The categories of this paper are: quant-ph
15
The categories of this paper are: nucl-ex
22
The categories of this paper are: chao-dyn
20
The categories of this paper are: acc-phys