7,765 research outputs found
Diffraction at HERA and the Confinement Problem
We discuss HERA data on the high energy behavior of the total gamma*p cross
section and on diffraction in deep inelastic scattering. We outline their
novelty in comparison with diffraction in high energy hadron hadron scattering.
As a physical picture, we propose an interpretation in terms of QCD radiation
at small and large distances: a careful study of the transition between the two
extremes represents a new approach to the QCD confinement problem.Comment: 30 pages. Some references adde
Quark-Antiquark-Gluon Jets in DIS Diffractive Dissociation
We study the diffractive production of jets with large transverse
momenta in the region of large diffractive masses (small ). Cross
sections for transverse and longitudinal photons are obtained in the leading
log 1/x_{\fP} and log approximation, keeping all powers in log
. We perform a numerical study and illustrate the angular
distribution of the three jets. We also estimate the integrated diffractive
three jet cross section and compare with the dijet cross section obtained
before.Comment: 28 pages (Latex), 20 figures (Postscript
Massive c\bar c g - Calculation in Diffractive DIS and Diffractive D^* - Production at HERA
We calculate the cross section for -production in diffractive DIS
with finite quark masses at zero momentum transfer . The calculation is done
in the leading log(1/) approximation and is valid in the region of high
diffractive masses (small ). We apply our cross section formula
including both - and in a Monte Carlo simulation to
diffractive meson production at HERA. We compare our predictions to
results of H1 using three parameterizations for the unintegrated gluon density.Comment: 11 pages, 5 figure
The BFKL-Pomeron In Deep Inelastic Diffractive Dissociation near t=0
The small- behaviour of the deep inelastic diffractive dissociation cross
section in the triple Regge region is investigated, using the BFKL
approximation in perturbative QCD. We show that the cross section is finite at
, but the diffusion in leads to a large contribution of small
momenta at the triple Pomeron vertex. We study the dependence upon the total
energy and the invariant mass. At , there is a decoupling of the three
BFKL singularities which is a consequence of the conservation of the conformal
dimension. For large invariant masses, the four gluon state in the upper
t-channel plays an important role and cannot be neglected.Comment: 43 pages, LaTex , 11 ps-figures (uuencoded) appende
An Analysis of Diffraction in Deep-Inelastic Scattering
We propose a simple parametrization for the deep-inelastic diffractive cross
section. It contains the contribution of production to both the
longitudinal and the transverse diffractive structure functions, and of the
production of final states from transverse photons. We start from
the hard region and perform a suitable extrapolation into the soft region. We
test our model on the 1994 ZEUS and H1 data, and confront it with the H1
conjecture of a singular gluon distribution.Comment: 24 pages, LaTeX, figures included using epsfi
The Small-x Behaviour of the Singlet Polarized Structure Function g_2 in the Double Logarithmic Approximation
The small-x behavior of the singlet contributions to the polarized structure
function g_2(x,Q^2) is calculated in the double-logarithmic approximation of
perturbative QCD. The dominant contribution is due to the gluons which, in
contrast to the unpolarized case, mix with the fermions also in the small-x
domain. We find a power-like growth in 1/x in the odd-signature parts of the
amplitude with the same power as in the singlet function g_1(x,Q^2) at x<< 1.Comment: 20 pages, latex, 3 ps figure
A Numerical Estimate of the Small- Region in the BFKL Pomeron
A computer study is performed to estimate the influence of the small-
region in the BFKL evolution equation. We consider the small-x region of the
deep inelastic structure function and show that the magnitude of the
small- region depends on and . We suggest that the width of the
-distribution in the final state may serve as an additional
footprint of BFKL dynamics. For diffractive dissociation it is shown that the
contribution of the infrared region is large - even for large . This
contribution becomes smaller only if restrictions on the final state are
imposed.Comment: 15 pages, latex, 9 figures ,revised version, some discussion added,
one reference added, two figures removed, final version to be published in
Phys. Lett.
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