493 research outputs found
The High Energy Radiation Pattern from BFKLex
We discuss a recent study on high-energy jet production in the multi-Regge
limit done with the use of the Monte Carlo event generator BFKLex which
includes collinear improvements in the form of double-log contributions. We
will show results for the average transverse momentum and azimuthal angle of
the final state jets when at least one of them is very forward in rapidity and
another one is very backward. We also discuss the introduction of a new
observable which accounts for the average rapidity ratio among subsequent
emissions.Comment: 6 pages, presented by G. Chachamis at the XXIV International Workshop
on Deep-Inelastic Scattering and Related Subjects, 11-15 April 2016, DESY
Hamburg, German
Two aspects of the Regge limit in QCD: Double Logs in Exclusive observables and Infrared Effects in Cross Sections
Two relevant points related to the application of the BFKL formalism to
phenomenology are discussed. First, we have presented a set of observables
characterizing multi-jet configurations event by event (average transverse
momentum, average azimuthal angle, average ratio of jet rapidities) which can
be used to find distinct signals of BFKL dynamics at the LHC. A numerical
analysis has been shown using the Monte Carlo event generator BFKLex, modified
to include higher-order collinear corrections in addition to the
transverse-momentum implementation of the NLO kernel. We require to have two
tagged forward/backward jets in the final state. Second, the structure of the
BFKL equation changes if infrared boundary conditions are imposed when
considering the running of the coupling. The cut in the complex angular
momentum plane becomes an infinite series of Regge poles. Integrating along a
contour off the real axis we find a strong dependence of the intercepts and
collinear regions on the choice of the boundary conditions. The mean transverse
scales dominant in the gluon ladder increase. This could have interesting
phenomenological consequences.Comment: 6 pages, presented by A. Sabio Vera at the 25th International
Workshop on Deep Inelastic Scattering and Related Topics, 3-7 April 2017,
Birmingham, U
Exclusive central production of heavy quarks at the LHC
We study the exclusive production of heavy flavors at central rapidities in
hadron-hadron collisions within the kT factorisation formalism. Since this
involves regions of small Bjorken x in the unintegrated gluon densities, we
include the next-to-leading order BFKL contributions working directly in
transverse momentum representation. Our results are presented in a form
suitable for Monte Carlo implementation.Comment: 10 pages, 1 figur
BFKL predictions for inclusive three jet production at the LHC
We define new observables sensitive to BFKL dynamics in the context of
multijet production at the large hadron collider (LHC). We propose the study of
the inclusive production of three jets well separated in rapidity from each
other, with two of them being very forward. We show that the tagging of a third
jet in the central region of rapidity allows for a very strong test of the BFKL
formalism. In particular, we have studied two projections on azimuthal angles
for the differential cross section which allow for the definition of many
different observables whose behavior when varying the and rapidity of the
central jet is a distinct signal of BFKL dynamics. In order to reduce the
theoretical uncertainties and influence of higher order corrections, we propose
the study of ratios of correlation functions of products of cosines of
azimuthal angle differences among the tagged jets.Comment: 11 pages, 2 figure
Gluon Regge trajectory at two loops from Lipatov's high energy effective action
We present the derivation of the two-loop gluon Regge trajectory using
Lipatov's high energy effective action and a direct evaluation of Feynman
diagrams. Using a gauge invariant regularization of high energy divergences by
deforming the light-cone vectors of the effective action, we determine the
two-loop self-energy of the reggeized gluon, after computing the master
integrals involved using the Mellin-Barnes representations technique. The
self-energy is further matched to QCD through a recently proposed subtraction
prescription. The Regge trajectory of the gluon is then defined through
renormalization of the reggeized gluon propagator with respect to high energy
divergences. Our result is in agreement with previous computations in the
literature, providing a non-trivial test of the effective action and the
proposed subtraction and renormalization framework.Comment: 22 page
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