89 research outputs found
The Mueller-Tang jet impact factor at NLO from the high energy effective action
We report on recent progress in the evaluation of next-to-leading order
observables using Lipatov's QCD high energy effective action. In this
contribution we focus on the determination of the real part of the
next-to-leading order corrections to the Mueller-Tang impact factor which is
the only missing element for a complete NLO BFKL description of quark induced
dijet events with a rapidity gap.Comment: 5 pages, Proceedings of 7th International Workshop on Diffraction in
High Energy Physics (Diffraction 2012
Forward Drell-Yan plus backward jet as a test of BFKL evolution
We study Drell-Yan plus jet events where the gauge boson is produced in the
forward direction of one of the colliding protons and a jet is produced in the
forward direction of the second proton. The resulting large rapidity difference
between the final states then opens up the phase space for BFKL evolution.
First numerical results on partonic level are provided.Comment: 4 pages, 2 figures, proceedings of the XX Workshop on Deep-Inelastic
Scattering and Related Subjects, 26-30 March, University of Bonn (2012
Transverse momentum dependent splitting functions at work: quark-to-gluon splitting
Using the recently obtained Pgq splitting function we extend the low x
evolution equation for gluons to account for contributions originating from
quark-to-gluon splitting. In order to write down a consistent equation we resum
virtual corrections coming from the gluon channel and demonstrate that this
implies a suitable regularization of the Pgq singularity, corresponding to a
soft emitted quark. We also note that the obtained equation is in a
straightforward manner generalized to a nonlinear evolution equation which
takes into account effects due to the presence of high gluon densities.Comment: 13 pages, 3 figures, published versio
A kT-dependent sea-quark density for the CASCADE Monte Carlo event generator
Parton-shower event generators that go beyond the collinear-ordering
approximation at small x have so far included only gluon and valence quark
channels at transverse momentum dependent level. We describe results of recent
work to include effects of the sea-quark distribution with explicit dependence
on the transverse quark-momentum.This sea-quark density is then applied to the
description of forward Z -production. The qq*->Z matrix element (with one
off-shell quark) is calculated in an explicit gauge invariant way, making use
of high energy factorization. The kT-factorized result has been implemented
into the CCFM Monte-Carlo CASCADE and a numerical comparison with the qg*->Zq
matrix element has been carried out.Comment: 4 pages, 4 figures, based on a talk given at the XXI Workshop on
Deep-Inelastic Scattering and Related Subjects, 11-15 April, Newport News,
Virginia (2011
TMD splitting functions in kT factorization: the real contribution to the gluon-to-gluon splitting
We calculate the transverse momentum dependent gluon-to-gluon splitting
function within -factorization, generalizing the framework employed in the
calculation of the quark splitting functions in [1-3] and demonstrate at the
same time the consistency of the extended formalism with previous results.
While existing versions of factorized evolution equations contain already
a gluon-to-gluon splitting function i.e. the leading order
Balitsky-Fadin-Kuraev-Lipatov (BFKL) kernel or the
Ciafaloni-Catani-Fiore-Marchesini (CCFM) kernel, the obtained splitting
function has the important property that it reduces both to the leading order
BFKL kernel in the high energy limit, to the
Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) gluon-to-gluon splitting
function in the collinear limit as well as to the CCFM kernel in the soft
limit. At the same time we demonstrate that this splitting kernel can be
obtained from a direct calculation of the QCD Feynman diagrams, based on a
combined implementation of the Curci-Furmanski-Petronzio formalism for the
calculation of the collinear splitting functions and the framework of high
energy factorization.Comment: 29 pages, 5 figures, published versio
Applications of Lipatov's high energy effective action to NLO BFKL jet phenomenology
We report on recent progress in the evaluation of next-to-leading order (NLO)
observables using Lipatov's QCD high energy effective action. We calculate both
real and virtual corrections to the quark induced forward jet vertex at NLO,
making use of a new regularization method and a subtraction mechanism. As a new
result we determine the real part of the NLO Mueller-Tang impact factor which
is the only missing element for a complete NLO BFKL description of dijet events
with a rapidity gap.Comment: 4 pages, 29 figures, proceedings of the XX Workshop on Deep-Inelastic
Scattering and Related Subjects, 26-30 March, University of Bonn (2012
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