Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Cutkosky rules and perturbative unitarity in Euclidean nonlocal quantum
  field theories   We prove the unitarity of the Euclidean nonlocal scalar field theory to all
perturbative orders in the loop expansion. The amplitudes in the Euclidean
space are calculated assuming that all the particles have purely imaginary
energies, and afterwards they are analytically continued to real energies. We
show that such amplitudes satisfy the Cutkowsky rules and that only the cut
diagrams corresponding to normal thresholds contribute to their imaginary part.
This implies that the theory is unitary. This analysis is then exported to
nonlocal gauge and gravity theories by means of Becchi-Rouet-Stora-Tyutin or
diffeomorphism invariance, and Ward identities.

8
The categories of this paper are: hep-ex
4
The categories of this paper are: cond-mat
27
The categories of this paper are: comp-gas
35
The categories of this paper are: mtrl-th
22
The categories of this paper are: chao-dyn
3
The categories of this paper are: physics
0
The categories of this paper are: hep-ph
14
The categories of this paper are: math-ph
24
The categories of this paper are: dg-ga
1
The categories of this paper are: cs
15
The categories of this paper are: nucl-ex
37
The categories of this paper are: supr-con
10
The categories of this paper are: q-bio
23
The categories of this paper are: solv-int
34
The categories of this paper are: chem-ph
31
The categories of this paper are: ao-sci