Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: W pair production cross-section and W branching fractions in e+e-
  interactions at 189 GeV   The cross-section for the process e+e- -> W+W- has been measured with the
data sample collected by DELPHI at an average centre-of-mass energy of 189 GeV
and corresponding to an integrated luminosity of 155 pb^{-1}. Based on the 2392
events selected as WW candidates, the cross-section for the doubly resonant
process e+e- -> W+W- has been measured to be 15.83 +- 0.38 (stat) +- 0.20
(syst) pb. The branching fractions of the W decay were also measured and found
to be in good agreement with the Standard Model expectation. From these a value
of the CKM mixing matrix element |V_{cs}| = 1.001 +- 0.040 (stat) +- 0.020
(syst) was derived.

28
The categories of this paper are: alg-geom
32
The categories of this paper are: atom-ph
14
The categories of this paper are: math-ph
2
The categories of this paper are: math
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
15
The categories of this paper are: nucl-ex
12
The categories of this paper are: nucl-th
37
The categories of this paper are: supr-con
31
The categories of this paper are: ao-sci
19
The categories of this paper are: eess
3
The categories of this paper are: physics
5
The categories of this paper are: gr-qc
30
The categories of this paper are: q-alg
33
The categories of this paper are: plasm-ph