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{\bf EPS-HEP99} \\
{\bf Abstract \# 000} \\
{\bf Parallel sessions: 1,3} \\
{\bf Plenary sessions:  1,6}
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\abstractheader{ {\bf 
Search for Instanton Induced Events in Deep-Inelastic 
Scattering at HERA  } \\ \\
H1 Collaboration, \\
DESY, Notkestr.85, D-22607 Hamburg, Germany
}

\abstractbody{
In QCD, anomalous non-perturbative processes are expected which
violate classical laws like the conservation of chirality.
Such processes are induced by Instantons.
They are non-perturbative fluctuations of the gluon field
inducing hard processes and represent tunneling
transitions between topologically inequivalent vacua. \\
In Deep-Inelastic Scattering (DIS) Instanton induced processes
are dominantly produced in a quark gluon fusion process.
The virtuality of the quark,
originating from a photon splitting into a $q\bar{q}$ pair in
the instanton background, provides a generic hard scale naturally limiting
the instanton size  and makes a quantitative prediction of the
cross-section possible. The expected cross section for 
the kinematical region $x_{bj} > 10^{-3}$ and $0.1 < y < 0.9$ 
is in the order of $100$ {\rm pb}. \\
The hadronic final state of instanton
induced events is simulated by the Monte Carlo program QCDINS. 
Based on the expected characteristics of the hadronic final state
of instanton induced processes (the production of particles with
large transverse momenta in a pseudo-rapidity band of $2$ units
and the isotropic decay of the instanton in its rest system) a
search for such processes is performed. 
The data sample covering $5 < Q^2 < 100\;\mbox{GeV}^2$ was
taken in the years 1996 -- 1997 and corresponds to an integrated luminosity of
${\cal L}_{int} \simeq 20\;\mbox{pb}^{-1}$. It contains about $1$ Million
DIS events. 
Assuming that the hadronic final state looks like simulated by QCDINS,
an upper limit on the cross section is set.
}

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