Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Amplitudes, recursion relations and unitarity in the Abelian Higgs Model   The Abelian Higgs model forms an essential part of the electroweak standard
model: it is the sector containing only Z and Higgs bosons. We present a
diagram-based proof of the tree-level unitarity of this model inside the
unitary gauge, where only physical degrees of freedom occur. We derive
combinatorial recursion relations for off-shell amplitudes in the massless
approximation, which allows us to prove the cancellation of the first two
orders in energy of unitarity-violating high-energy behaviour for any
tree-level amplitude in this model. We describe a deformation of the amplitudes
by extending the physical phase space to at least 7 spacetime dimensions, which
leads to on-shell recursion relations a la BCFW. These lead to a simple proof
that all on-shell tree amplitudes obey partial-wave unitarity.

8
The categories of this paper are: hep-ex
13
The categories of this paper are: quant-ph
6
The categories of this paper are: astro-ph
2
The categories of this paper are: math
14
The categories of this paper are: math-ph
7
The categories of this paper are: hep-th
30
The categories of this paper are: q-alg
34
The categories of this paper are: chem-ph
31
The categories of this paper are: ao-sci
28
The categories of this paper are: alg-geom
16
The categories of this paper are: stat
18
The categories of this paper are: econ
20
The categories of this paper are: acc-phys
26
The categories of this paper are: bayes-an
32
The categories of this paper are: atom-ph
35
The categories of this paper are: mtrl-th