Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the introduction of a boundary in topological field theories   We study the consequences of the presence of a boundary in topological field
theories in various dimensions. We characterize, univocally and on very general
grounds, the field content and the symmetries of the actions which live on the
boundary. We then show that these actions are covariant, despite appearances.
We show also that physically relevant theories like the 2D Luttinger liquid
model, or the 4D Maxwell theory, can be seen as boundary reductions of higher
dimensional topological field theories, which do not display local observables.

15
The categories of this paper are: nucl-ex
35
The categories of this paper are: mtrl-th
33
The categories of this paper are: plasm-ph
20
The categories of this paper are: acc-phys
27
The categories of this paper are: comp-gas
3
The categories of this paper are: physics
22
The categories of this paper are: chao-dyn
10
The categories of this paper are: q-bio
13
The categories of this paper are: quant-ph
19
The categories of this paper are: eess
32
The categories of this paper are: atom-ph
23
The categories of this paper are: solv-int
11
The categories of this paper are: hep-lat
36
The categories of this paper are: cmp-lg
25
The categories of this paper are: patt-sol
28
The categories of this paper are: alg-geom