52 research outputs found
Study of the Linked Dipole Chain Model in heavy quark production at the Tevatron
We present calculations of charm and beauty production at Tevatron within the
framework of kT-factorization, using the unintegrated gluon distributions as
obtained from the Linked Dipole Chain model. The analysis covers transverse
momentum and rapidity distributions and the azimuthal correlations between b
and bbar quarks (or rather muons from their decay) which are powerful tests for
the different unintegrated gluon distributions. We compare the theoretical
results with recent experimental data taken by D0 and CDF collaborations at the
Tevatron Run I and II.Comment: 16 page
Unintegrated gluon distributions in D* and dijet associated photoproduction at HERA
We consider the photoproduction of D* mesons associated with two hadron jets
at HERA collider in the framework of the kt-factorization approach. The
unintegrated gluon densities in a proton are obtained from the full CCFM, from
unified BFKL-DGLAP evolution equations as well as from the Kimber-Martin-Ryskin
prescription. Resolved photon contributions are reproduced by the initial-state
gluon radiation. We investigate different production rates and make comparison
with the recent experimental data taken by the ZEUS collaboration. Special
attention is put on the specific dijet correlations which can provide unique
information about non-collinear gluon evolution dynamics.Comment: 31 pages, 18 figure
Double heavy meson production through double parton scattering in hadronic collisions
It is shown that the contribution from double parton scattering to the
inclusive double heavy meson yield is quite comparable with the usually
considered mechanism of their production at the LHC energy. For some pairs of
heavy flavored quarks in the final state the double parton scattering will be a
dominant mode of their production.Comment: 5 pages, version accepted in Phys. Lett. B, discussion extended,
references adde
The Spin-Dependent Structure Functions of Nuclei in the Meson-Nucleon Theory
A theoretical approach to the investigation of spin-dependent structure
functions in deep inelastic scattering of polarized leptons off polarized
nuclei, based on the effective meson-nucleon theory and operator product
expansion method, is proposed and applied to deuteron and . The explicit
forms of the moments of the deuteron and spin-dependent structure
functions are found and numerical estimates of the influence of nuclear
structure effects are presented.Comment: 42 pages revtex, 7 postscript figures available from above e-mail
upon request. Perugia preprint DFUPG 92/9
Solution of the Kwiecinski evolution equations for unintegrated parton distributions using the Mellin transform
The Kwiecinski equations for the QCD evolution of the unintegrated parton
distributions in the transverse-coordinate space (b) are analyzed with the help
of the Mellin-transform method. The equations are solved numerically in the
general case, as well as in a small-b expansion which converges fast for b
Lambda_QCD sufficiently small. We also discuss the asymptotic limit of large bQ
and show that the distributions generated by the evolution decrease with b
according to a power law. Numerical results are presented for the pion
distributions with a simple valence-like initial condition at the low scale,
following from chiral large-N_c quark models. We use two models: the Spectral
Quark Model and the Nambu--Jona-Lasinio model. Formal aspects of the equations,
such as the analytic form of the b-dependent anomalous dimensions, their
analytic structure, as well as the limits of unintegrated parton densities at x
-> 0, x -> 1, and at large b, are discussed in detail. The effect of spreading
of the transverse momentum with the increasing scale is confirmed, with
growing asymptotically as Q^2 alpha(Q^2). Approximate formulas for
for each parton species is given, which may be used in practical
applications.Comment: 18 pages, 6 figures, RevTe
Observation of hard scattering in photoproduction events with a large rapidity gap at HERA
Events with a large rapidity gap and total transverse energy greater than 5
GeV have been observed in quasi-real photoproduction at HERA with the ZEUS
detector. The distribution of these events as a function of the
centre of mass energy is consistent with diffractive scattering. For total
transverse energies above 12 GeV, the hadronic final states show predominantly
a two-jet structure with each jet having a transverse energy greater than 4
GeV. For the two-jet events, little energy flow is found outside the jets. This
observation is consistent with the hard scattering of a quasi-real photon with
a colourless object in the proton.Comment: 19 pages, latex, 4 figures appended as uuencoded fil
Observation of Events with an Energetic Forward Neutron in Deep Inelastic Scattering at HERA
In deep inelastic neutral current scattering of positrons and protons at the center of mass energy of 300 GeV, we observe, with the ZEUS detector, events with a high energy neutron produced at very small scattering angles with respect to the proton direction. The events constitute a fixed fraction of the deep inelastic, neutral current event sample independent of Bjorken x and Q2 in the range 3 · 10-4 \u3c xBJ \u3c 6 · 10-3 and 10 \u3c Q2 \u3c 100 GeV2
Regge poles and π Δ (1236) photo production
The Regge-pole model is used to obtain expressions for the differential cross section and the polarization isobar-density matrix for the γN → π Δ (1236) process with an account of the ρ{variant}, A2, and π trajectories. © 1972 Consultants Bureau
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