A. Papa

Electroproduction of two light vector mesons in the next-to-leading approximation

Abstract We calculate the amplitude for the forward electroproduction of two light vector mesons in next-to-leading order BFKL. This amplitude is written as a convolution of two impact factors for the virtual photon to light vector meson transition with the BFKL Greens function. It represents the first next-to-leading order amplitude ever calculated for a collision process between strongly interacting colorless particles.

Mueller-Navelet small-cone jets at LHC in next-to-leading BFKL

We consider within QCD collinear factorization the process p + p → jet + jet + X, where two forward high-pT jets are produced with a large separation in rapidityy (Mueller-Navelet jets). In this case the (calculable) hard part of the reaction receives large higher-order corrections ∼ � n (�y) n , which can be accounted for in the BFKL ap- proach with next-to-leading logarithmic accuracy, including contributions ∼ � n(�y) n−1 . We calculate several observables related with this process, using the next-to-leading or- der jet vertices, recently calculated in the approximation of small aperture of the jet cone in the pseudorapidity-azimuthal angle plane.

The next-to-leading order jet vertex for Mueller-Navelet and forward jets revisited

A bstractWe recalculate, within the BFKL approach and at the next-to-leading order, the jet vertex relevant for the production of Mueller-Navelet jets in proton collisions and of forward jets in DIS. We consider both processes with incoming quark and gluon. The starting point is the definition of quark and gluon impact factors in the BFKL approach. Following this procedure we show explicitly that all infrared divergences cancel when renormalized parton densities are considered. We compare our results for the vertex with the former calculation of refs. [1, 2].

The next-to-leading order forward jet vertex in the small-cone approximation

A bstractWe consider within QCD collinear factorization the process p + p → jet + jet + s X , where two forward high-pT jets are produced with a large separation in rapidity ∆y (Mueller-Navelet jets). In this case the (calculable) hard part of the reaction receives large higher-order corrections

Collinear improvement of the BFKL kernel in the electroproduction of two light vector mesons

\sim \alpha_s^n{\left( {\Delta y} \right)^n}

Inclusive production of a pair of hadrons separated by a large interval of rapidity in proton collisions

, which can be accounted for in the BFKL approach.In particular, we calculate in the next-to-leading order the impact factor (vertex) for the production of a forward high-pT jet, in the approximation of small aperture of the jet cone in the pseudorapidity-azimuthal angle plane. The final expression for the vertex turns out to be simple and easy to implement in numerical calculations.

One loop Reggeon-Reggeon gluon vertex at arbitrary space-time dimension

The forward electroproduction of two light vector mesons is the first example of a collision process between strongly interacting colorless particles for which the amplitude can be written completely within perturbative QCD in the Regge limit with next-to-leading accuracy. In a previous paper we have given a numerical determination of the amplitude in the case of equal photon virtualities by using a definite representation for the amplitude and a definite optimization method for the perturbative series. Here we estimate the systematic uncertainty of our previous determination, by considering a different representation of the amplitude and different optimization methods of the perturbative series. Moreover, we compare our result for the differential cross section at the minimum |t| with a different approach, based on collinear kernel improvement.

Connection between complete and Möbius forms of gauge invariant operators

The use of the BFKL kernel improved by the inclusion of subleading terms generated by renormalization group (RG) analysis has been suggested to cure the instabilities in the behavior of the BFKL Green’s function in the next-to-leading approximation (NLA). We test the performance of a RG-improved kernel in the determination of the amplitude of a physical process, the electroproduction of two light vector mesons, in the BFKL approach in the NLA. We find that a smooth behavior of the amplitude with the center-of-mass energy can be achieved, setting the renormalization and energy scales appearing in the subleading terms to values much closer to the kinematical scales of the process than in the approaches based on the unimproved kernel.