Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Measuring sigma(e+ e- --> hadrons) with Tagged Photons at Electron
  Positron Colliders   A Monte Carlo generator has been constructed to simulate the reaction e+ e-
--> gamma + 2 pions and gamma + 4 pions, where the photon is assumed to be
observed in the detector. Predictions are presented for cms energies of 1GeV,
3GeV and 10GeV, corresponding to the energies of DAPHNE, BEBC and of B-meson
factories. The event rates are sufficiently high to allow for a precise
measurement of R(Q^2) in the region of Q between approximately 1GeV and 2.5GeV.
Estimates for the kinematic breaking of isospin relations between different
channels as a consequence of the mass difference between charged and neutral
pions are given.

20
The categories of this paper are: acc-phys
28
The categories of this paper are: alg-geom
3
The categories of this paper are: physics
31
The categories of this paper are: ao-sci
21
The categories of this paper are: adap-org
15
The categories of this paper are: nucl-ex
27
The categories of this paper are: comp-gas
16
The categories of this paper are: stat
9
The categories of this paper are: nlin
13
The categories of this paper are: quant-ph
7
The categories of this paper are: hep-th
1
The categories of this paper are: cs
18
The categories of this paper are: econ
30
The categories of this paper are: q-alg
25
The categories of this paper are: patt-sol
14
The categories of this paper are: math-ph