607 research outputs found
Zooming-in on Instantons at HERA
In view of the intriguing, preliminary search results for instanton-induced
events at HERA from the H1 collaboration, some important remaining theoretical
issues are discussed. Notably, the question is addressed, to which extent the
H1 analysis may be directly compared to our original predictions from
instanton-perturbation theory, since certain fiducial cuts are lacking in the
H1 data. Various theoretical uncertainties are evaluated and their impact on
the observed excess is discussed. An improved understanding of the experimental
findings along with an encouraging over-all agreement with our original
predictions seems to emerge.Comment: 13 pages, 12 figure
QCDINS 2.0 - A Monte Carlo generator for instanton-induced processes in deep-inelastic scattering
We describe a Monte Carlo event generator for the simulation of QCD-instanton
induced processes in deep-inelastic scattering (HERA). The QCDINS package is
designed as an ``add-on'' hard process generator interfaced to the general
hadronic event simulation package HERWIG. It incorporates the theoretically
predicted production rate for instanton-induced events as well as the essential
characteristics that have been derived theoretically for the partonic final
state of instanton-induced processes: notably, the flavour democratic and
isotropic production of the partonic final state, energy weight factors
different for gluons and quarks, and a high average multiplicity O(10) of
produced partons with a Poisson distribution of the gluon multiplicity. While
the subsequent perturbative evolution of the generated partons is always
handled by the HERWIG package, the final hadronization step may optionally be
performed also by means of the general hadronic event simulation package
JETSET.Comment: 51 pages, 3 figure
Theory and Phenomenology of Instantons at HERA
We review our on-going theoretical and phenomenological investigation of the
prospects to discover QCD-instantons in deep-inelastic scattering at HERA.Comment: 18 pages, 15 figures; contribution to the Ringberg Workshop ``New
Trends in HERA Physics'', Ringberg Castle, Tegernsee, Germany, May 30 - June
4, 1999; to be published in the proceeding
Towards the Phenomenology of QCD-Instanton Induced Particle Production
We present a first status report on a broad and systematic study of possible
manifestations of QCD-instantons at HERA. Considerable motivation comes from
the close analogy between instanton-induced violation in electroweak
processes and effects of QCD-instantons in deep inelastic scattering. We
concentrate on the high multiplicity final state structure, reminiscent of an
isotropically decaying ``fireball''. A set of experimental isolation criteria
is proposed. They serve to further enhance the striking event signature without
significantly suppressing the expected rates.Comment: 32 pages, latex, epsfig, 11 uuencoded figure
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