Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Vanishing or non-vanishing rainbow? Reduction formulas of electric
  dipole moment   In this paper, we derive a simplified formula of electric dipole moments
(EDMs) of a fermion. In the Standard Model, it is well-known that non-trivial
cancellations between some rainbow-type diagrams induced by $W$ boson exchanges
occur in the calculation of the neutron EDM at the two-loop level due to the
gauge symmetry. The fermion self-energy and the vertex correction are related
through the Ward-Takahashi identity, and this relation causes the exact
cancellation of the EDM. We derive EDM formulas for a more general setup by
introducing the form factors for the fermion self-energy and the vertex
correction so that the derived formulas can be applicable to a larger class of
models. We conclude that the non-zero EDM contributions are induced from
rainbow-type diagrams with the chirality flipping effects for internal
fermions. We also discuss the other possible generalization of the EDM
calculation which is applicable to the other classes of models.

11
The categories of this paper are: hep-lat
3
The categories of this paper are: physics
18
The categories of this paper are: econ
17
The categories of this paper are: q-fin
34
The categories of this paper are: chem-ph
36
The categories of this paper are: cmp-lg
25
The categories of this paper are: patt-sol
12
The categories of this paper are: nucl-th
24
The categories of this paper are: dg-ga
16
The categories of this paper are: stat
8
The categories of this paper are: hep-ex
26
The categories of this paper are: bayes-an
30
The categories of this paper are: q-alg
7
The categories of this paper are: hep-th
15
The categories of this paper are: nucl-ex
35
The categories of this paper are: mtrl-th