Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: General formulae for f1 --> f2 gamma   At one-loop level the decay f1 --> f2 gamma, where f1 and f2 are two spin-1/2
particles with the same electric charge, is mediated by a boson B and a
spin-1/2 fermion F. The boson B may have either spin 0 - interacting with the
fermions through Dirac matrices 1 and gamma5 - or spin 1 - with V+A and V-A
couplings to the fermions. I give general formulae for the one-loop electroweak
amplitude of f1 --> f2 gamma in all these cases.

8
The categories of this paper are: hep-ex
12
The categories of this paper are: nucl-th
23
The categories of this paper are: solv-int
27
The categories of this paper are: comp-gas
33
The categories of this paper are: plasm-ph
2
The categories of this paper are: math
17
The categories of this paper are: q-fin
37
The categories of this paper are: supr-con
5
The categories of this paper are: gr-qc
3
The categories of this paper are: physics
13
The categories of this paper are: quant-ph
20
The categories of this paper are: acc-phys
18
The categories of this paper are: econ
22
The categories of this paper are: chao-dyn
6
The categories of this paper are: astro-ph
30
The categories of this paper are: q-alg