6,874 research outputs found
Erratum: Solution of periodic Poisson's equation and the Hartree-Fock approach for solids with extended electron states: application to linear augmented plane wave method
Erratum to Int. J. Quantum Chem. v. 89, pp. 57-85 (2002)Comment: 1 pag
The Running BFKL: Resolution of Caldwell's Puzzle
The HERA data on the proton structure function, , at very small
and show the dramatic departure of the logarithmic slope, , from theoretical predictions based on the DGLAP
evolution. We show that the running BFKL approach provides the quantitative
explanation for the observed and/or -dependence of .Comment: 7 pages, Latex, 4 Figures, P
Breaking of k_\perp-factorization for Single Jet Production off Nuclei
The linear k_\perp-factorization is part and parcel of the pQCD description
of high energy hard processes off free nucleons.
In the case of heavy nuclear targets the very concept of nuclear parton
density becomes ill-defined as exemplified by the recent derivation [2] of
nonlinear nuclear k_\perp-factorization for forward dijet production in DIS off
nuclei. Here we report a derivation of the related breaking of
k_\perp-factorization for single-jet processes. We present a general formalism
and apply it to several cases of practical interest: open charm and quark and
gluon jet production in the central to beam fragmentation region of
\gamma^*p,\gamma^*A, pp and pA collisions. We show how the pattern of
k_\perp-factorization breaking and the nature and number of exchanged nuclear
pomerons do change within the phase space of produced quark and gluon jets. As
an application of the nonlinear k_\perp-factorization we discuss the Cronin
effect. Our results are also applicable to the p_\perp-dependence of the
Landau-Pomeranchuk-Migdal effect for, and nuclear quenching of, jets produced
in the proton hemisphere of pA collisions.Comment: 55 pages, 9 eps figures, presentation shortened, a number of typos
removed, to appear in Phys. Rev.
Possible Odderon discovery at HERA via charge asymmetry in the diffractive pi+pi- production
We discuss how the evasive Odderon signal can be enhanced by final state
interactions. We suggest the charge asymmetry of pion spectra in diffractive
pi+pi- photoproduction as a promising signature of the Odderon exchange.Comment: 4 pages, To appear in Proceedings of the 9th International Workshop
on Deep Inelastic Scattering (DIS2001), Bologna, Italy, 27 Apr. - 1 May 200
The hard scale in the exclusive rho-meson production in diffractive DIS
We re-examine the issue of the pQCD factorization scale in the exclusive rho
production in diffractive DIS from the k_t-factorization point of view. We find
that this scale differs significantly from, and possesses much flatter Q^2
behavior than widely used value (Q^2 + m_\rho^2)/4. With these results in mind,
we discuss the Q^2 shape of the rho meson production cross section. We
introduce rescaled cross sections, which might provide further insight into the
dynamics of rho production. We also comment on the recent ZEUS observation of
energy-independent ratio sigma(gamma* p --> rho p) / sigma_{tot}(gamma*p).Comment: 14 pages, 7 eps figure
Non-linear BFKL dynamics: color screening vs. gluon fusion
A feasible mechanism of unitarization of amplitudes of deep inelastic
scattering at small values of Bjorken is the gluon fusion. However, its
efficiency depends crucially on the vacuum color screening effect which
accompanies the multiplication and the diffusion of BFKL gluons from small to
large distances. From the fits to lattice data on field strength correlators
the propagation length of perturbative gluons is fermi. The
probability to find a perturbative gluon with short propagation length at large
distances is suppressed exponentially. It changes the pattern of (dif)fusion
dramatically. The magnitude of the fusion effect appears to be controlled by
the new dimensionless parameter , with the diffraction cone
slope standing for the characteristic size of the interaction region. It
should slowly decrease at large . Smallness of the
ratio makes the non-linear effects rather weak even at lowest
Bjorken available at HERA. We report the results of our studies of the
non-linear BFKL equation which has been generalized to incorporate the running
coupling and the screening radius as the infrared regulator.Comment: 16 pages, 2 figures, version accepted for publication, references
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