Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A new scale in the sky   The existence of a new ultraviolet scale $\Lambda=g M_P$ for effective
theories with gravity and U(1) gauge fields has recently been conjectured as a
possible criterion for distinguishing parts of the swampland from the string
landscape. Here we discuss a possible phenomenological signature of this scale,
for electromagnetic fields, in astrophysical observations.

11
The categories of this paper are: hep-lat
24
The categories of this paper are: dg-ga
18
The categories of this paper are: econ
3
The categories of this paper are: physics
21
The categories of this paper are: adap-org
34
The categories of this paper are: chem-ph
29
The categories of this paper are: funct-an
8
The categories of this paper are: hep-ex
19
The categories of this paper are: eess
15
The categories of this paper are: nucl-ex
12
The categories of this paper are: nucl-th
14
The categories of this paper are: math-ph
27
The categories of this paper are: comp-gas
37
The categories of this paper are: supr-con
32
The categories of this paper are: atom-ph
31
The categories of this paper are: ao-sci