Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Time-like and space-like electromagnetic form factors of nucleons, a
  unified description   The extended Lomon-Gari-Kr\"umpelmann model of nucleon electromagnetic form
factors, which embodies \rho, \rho', \omega, \omega' and \phi vector meson
contributions and the perturbative QCD high momentum transfer behavior has been
extended to the time-like region. Breit-Wigner formulae with momentum-dependent
widths have been considered for broad resonances in order to have a
parametrization for the electromagnetic form factors that fulfills, in the
time-like region, constraints from causality, analyticity, and unitarity. This
analytic extension of the Lomon-Gari-Kr\"umpelmann model has been used to
perform a unified fit to all the nucleon electromagnetic form factor data, in
the space-like and time-like region (where form factor values are extracted
from e+e- <-> nucleon-antinucleon cross sections data). The knowledge of the
complete analytic structure of form factors enables predictions at extended
momentum transfer, and also of time-like observables such as the ratio between
electric and magnetic form factors and their relative phase.

7
The categories of this paper are: hep-th
17
The categories of this paper are: q-fin
31
The categories of this paper are: ao-sci
34
The categories of this paper are: chem-ph
33
The categories of this paper are: plasm-ph
11
The categories of this paper are: hep-lat
29
The categories of this paper are: funct-an
1
The categories of this paper are: cs
6
The categories of this paper are: astro-ph
22
The categories of this paper are: chao-dyn
4
The categories of this paper are: cond-mat
30
The categories of this paper are: q-alg
35
The categories of this paper are: mtrl-th
14
The categories of this paper are: math-ph
37
The categories of this paper are: supr-con
28
The categories of this paper are: alg-geom