Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: QCD studies with e+e- annihilation data at 172-189 GeV   We have studied hadronic events from e+e- annihilation data at centre-of-mass
energies of sqrt{s}=172, 183 and 189 GeV. The total integrated luminosity of
the three samples, measured with the OPAL detector, corresponds to 250 pb^-1.
  We present distributions of event shape variables, charged particle
multiplicity and momentum, measured separately in the three data samples. From
these we extract measurements of the strong coupling alpha_s, the mean charged
particle multiplicity <nch> and the peak position xi_0 in the xi_p=ln(1/x_p)
distribution.
  In general the data are described well by analytic QCD calculations and Monte
Carlo models. Our measured values of alpha_s, <nch> and xi_0 are consistent
with previous determinations at sqrt{s}=MZ.

30
The categories of this paper are: q-alg
22
The categories of this paper are: chao-dyn
4
The categories of this paper are: cond-mat
9
The categories of this paper are: nlin
12
The categories of this paper are: nucl-th
5
The categories of this paper are: gr-qc
16
The categories of this paper are: stat
7
The categories of this paper are: hep-th
11
The categories of this paper are: hep-lat
1
The categories of this paper are: cs
24
The categories of this paper are: dg-ga
17
The categories of this paper are: q-fin
28
The categories of this paper are: alg-geom
29
The categories of this paper are: funct-an
32
The categories of this paper are: atom-ph
35
The categories of this paper are: mtrl-th