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

Using the BFKL resummation to fit DIS data: collinear and running coupling effects

The proton structure function F2 is studied in the low x regime using BFKL evolution. The next to leading logarithmic (NLL) analysis requires the inclusion of running coupling effects which lead to off-diagonal terms in the evolution kernel. An all-orders resummation is used to improve the collinear behavior of the NLL BFKL result. We emphasize the theoretical uncertainties that appear throughout the analysis and give a comparison to the combined HERA data.Comment: 4 pages, 5 figures, proceedings of the XX Workshop on Deep-Inelastic Scattering and Related Subjects, 26-30 March, University of Bonn (2012

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

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

The quark induced Mueller-Tang jet impact factor at next-to-leading order

We present the NLO corrections for the quark induced forward production of a jet with an associated rapidity gap. We make use of Lipatov's QCD high energy effective action to calculate the real emission contributions to the so-called Mueller-Tang impact factor. We combine them with the previously calculated virtual corrections and verify ultraviolet and collinear finiteness of the final result.Comment: 29 pages, many figure

Dijet Production at Large Rapidity Separation in N=4 SYM

Ratios of azimuthal angle correlations between two jets produced at large rapidity separation are studied in the N=4 super Yang-Mills theory (MSYM). It is shown that these observables, which directly prove the SL(2,C) symmetry present in gauge theories in the Regge limit, exhibit an excellent perturbative convergence. They are compared to those calculated in QCD for different renormalization schemes concluding that the momentum-substraction (MOM) scheme with the Brodsky-Lepage-Mackenzie (BLM) scale-fixing procedure captures the bulk of the MSYM results.Comment: 13 pages, 7 figure

The next-to-leading order vertex for a forward jet plus a rapidity gap at high energies

We present the results for the calculation of the forward jet vertex associated to a rapidity gap (coupling of a hard pomeron to the jet) in the Balitsky-Fadin-Kuraev-Lipatov (BFKL) formalism at next-to-leading order (NLO). We handle the real emission contributions making use of the high energy effective action proposed by Lipatov, valid for multi-Regge and quasi-multi-Regge kinematics. This result is important since it allows, together with the NLO non-forward gluon Green function, to perform NLO studies of jet production in diffractive events (Mueller-Tang dijets, as a well-known example).Comment: 12 pages, some figure

Quark contribution to the gluon Regge trajectory at NLO from the high energy effective action

The two loop (NLO) diagrams with quark content contributing to the gluon Regge trajectory are computed within the framework of Lipatov's effective action for QCD, using the regularization procedure for longitudinal divergencies recently proposed by two of us in http://arXiv.org/abs/arXiv:1110.6741. Perfect agreement with previous results in the literature is found, providing a robust check of the regularization prescription and showing that the high energy effective action is a very useful computational tool in the quasi-multi-Regge limit.Comment: 12 page, many figure