Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: New high order relations between physical observables in perturbative
  QCD   We exploit the fact that within massless perturbative QCD the same Green's
function determines the hadronic contribution to the $\tau$ decay width and the
moments of the $e^+e^-$ cross section. This allows one to obtain relations
between physical observables in the two processes up to an unprecedented high
order of perturbative QCD. A precision measurement of the $\tau$ decay width
allows one then to predict the first few moments of the spectral density in
$e^+e^-$ annihilations integrated up to $s\sim m_\tau^2$ with high accuracy.
The proposed tests are in reach of present experimental capabilities.

34
The categories of this paper are: chem-ph
32
The categories of this paper are: atom-ph
24
The categories of this paper are: dg-ga
19
The categories of this paper are: eess
31
The categories of this paper are: ao-sci
35
The categories of this paper are: mtrl-th
16
The categories of this paper are: stat
5
The categories of this paper are: gr-qc
36
The categories of this paper are: cmp-lg
23
The categories of this paper are: solv-int
18
The categories of this paper are: econ
26
The categories of this paper are: bayes-an
13
The categories of this paper are: quant-ph
1
The categories of this paper are: cs
6
The categories of this paper are: astro-ph
10
The categories of this paper are: q-bio