39 research outputs found
Unintegrated parton distributions and correlation functions
We discuss the limitations of the standard collinear approach. The
kinematical approximations necessary to derive the collinear factorization are
insufficient for the description of the exclusive final states. We argue that
for a proper treatment of the final states one needs to use fully unintegrated
parton correlation functions. We introduce the gauge invariant definitions of
these objects and the factorization theorem for one jet production in deep
inelastic scattering.Comment: 6 pages, 3 figures, pdflatex. Talk presented at 12th International
Conference on Elastic and Diffractive Scattering, Hamburg, DES
RHIC physics: short overview
This talk gives a very short overview of some of the important physical
phenomena observed at the Relativistic Heavy Ion Collider (RHIC). The emphasis
is put on the multiplicities, hard probes and the properties of the initial
state.Comment: 8 pages, 5 figures, pdflatex. Talk presented at 12th International
Conference on Elastic and Diffractive Scattering, in Hamburg, DES
Drell-Yan process at forward rapidity at the LHC
We analyze the Drell-Yan lepton pair production at forward rapidity at the
Large Hadron Collider. Using the dipole framework for the computation of the
cross section we find a significant suppression in comparison to the collinear
factorization formula due to saturation effects in the dipole cross section. We
develop a twist expansion in powers of Q_s^2/M^2 where Q_s is the saturation
scale and M the invariant mass of the produced lepton pair. For the nominal LHC
energy the leading twist description is sufficient down to masses of 6 GeV.
Below that value the higher twist terms give a significant contribution.Comment: 13 pages, 7 figure
Small x resummation and the Odderon
We present a general argument which suggests that the Bartels-Lipatov-Vacca
Odderon intercept should be equal to one to all orders in the perturbation
theory. The argument is based on the validity of the so called omega-expansion
in the high energy limit. It can be further supported by the analogous pattern
observed in the case of the anomalous dimensions which is a consequence of the
momentum sum rule. In addition, we conjecture that the BFKL kernel should
satisfy the transverse momentum sum rule. Finally, it is shown that the higher
order kinematical effects do not change the BLV Odderon intercept.Comment: 13 pages, 4 figure
BFKL Pomeron loop contribution in diffractive photoproduction and inclusive hadroproduction of and
We analyze contributions to the heavy vector meson production with large
transverse momentum in proton--proton and diffractive photon--proton scattering
driven by an exchange of two Balitsky--Fadin--Kuraev--Lipatov Pomerons in the
squared amplitudes. The Pomerons couple to a single parton and form a Pomeron
loop closed by the vector meson impact factors. For the photon--proton case the
diffractive cut of the Pomeron loop contributes, and for the inclusive
hadroproduction one finds the loop with two cut Pomerons. We compute both of
these Pomeron loop contributions and study in detail their properties. The
results are then used to calculate the cross sections for diffractive
photoproduction with large transverse momentum at HERA and the correlated two
Pomeron contribution for inclusive and production cross
sections at the LHC. Within a unified approach a good description of the
photoproduction data is found, but correlated two Pomeron mechanism gives only
a small contribution to hadroproduction of the vector mesons at the LHC.Comment: 34 pages, 16 figure
Universality of multi-particle production in QCD at high energies
By studying the color structure of multi-particle production processes in
p+A-type (dilute-dense) collisions, we find that higher-point functions beyond
typical dipoles and quadrupoles, e.g., sextupoles, octupoles, etc., naturally
appear in the cross sections, but are explicitly suppressed in the large-N_c
limit. We evaluate the sextupole in the McLerran-Venugopalan model and find
that, in general, its analytical form cannot be written as combination of
dipoles and quadrupoles. Within the Color Glass Condensate framework, we
present a proof that in the large-N_c limit, all multi-particle production
processes in the collision of a dilute system off a dense can, up to all orders
in \alpha_s, be described in terms of only dipoles and quadrupoles.Comment: 24 pages, 16 figures, Published in Phys.Rev.
Structure functions from renormalization group improved small evolution
We perform the fit to the structure function data from HERA including
terms due to the resummation at small . The equation for the unintegrated
gluon density is solved, previously established within the renormalization
group improved small framework. We find very good description of the
structure function and its charm component . The resulting
unintegrated gluon density is found to be consistent with the calculations
based on similar approaches available in the literature, with only slightly
higher intercept value.Comment: 35 pages, 16 figure