F. Caporale

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].

Stability of Azimuthal-angle Observables under Higher Order Corrections in Inclusive Three-jet Production

Recently, a new family of observables consisting of azimuthal-angle generalised ratios was proposed in a kinematical setup that resembles the usual Mueller-Navelet jets but with an additional tagged jet in the central region of rapidity. Non-tagged minijet activity between the three jets can affect significantly the azimuthal angle orientation of the jets and is accounted for by the introduction of two BFKL gluon Green functions. Here, we calculate the, presumably, most relevant higher order corrections to the observables by now convoluting the three leading-order jet vertices with two gluon Green functions at next-to-leading logarithmic approximation. The corrections appear to be mostly moderate giving us confidence that the recently proposed observables are actually an excellent way to probe the BFKL dynamics at the LHC. Furthermore, we allow for the jets to take values in different rapidity bins in various configurations such that a comparison between our predictions and the experimental data is a straightforward task.

NLO forward jet vertex

We calculate in the BFKL approach the jet vertex relevant for the production of Mueller-Navelet jets in proton-proton collisions. We consider both cases of incoming quark and gluon and show explicitly that all infrared divergences cancel when renormalized parton densities are considered. Finally we compare our expression for the vertex with a previous calculation [1].

Erratum to: Mueller–Navelet jets in next-to-leading order BFKL: theory versus experiment

We study, within QCD collinear factorization and including BFKL resummation at the next-to-leading order, the production of Mueller-Navelet jets at LHC with center-of-mass energy of 7 TeV. The adopted jet vertices are calculated in the approximation of small aperture of the jet cone in the pseudorapidity-azimuthal angle plane. We consider several representations of the dijet cross section, differing only beyond the next-to-leading order, to calculate a few observables related with this process. We use various methods of optimization to fix the energy scales entering the perturbative calculation and compare thereafter our results with the experimental data from the CMS collaboration.

Mueller-Navelet jets in high-energy hadron collisions

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 rapidity Δy (Mueller-Navelet jets [1]). The hard part of the reaction receives large higher-order corrections ∼ αns (Δy)n, which can be accounted for in the BFKL approach. We calculate cross section and azimuthal decorrelation, using the next-to-leading order jet vertices, in the small-cone approximation [2].

Inclusive three- and four-jet production in multi-Regge kinematics at the LHC

A study of differential cross sections for the production of three and four jets in multi-Regge kinematics is presented. The main focus lies on the azimuthal angle dependences in events with two forward/backward jets tagged in the final state. Furthermore, the tagging of one or two extra jets in more central regions of the detector with a relative separation in rapidity from each other is requested. It is found that the dependence of the cross sections on the transverse momenta and the rapidities of the central jet(s) can offer new means of studying the onset of BFKL dynamics.A study of differential cross sections for the production of three and four jets in multi-Regge kinematics is presented. The main focus lies on the azimuthal angle dependences in events with two forward/backward jets tagged in the final state. Furthermore, the tagging of one or two extra jets in more central regions of the detector with a relative separation in rapidity from each other is requested. It is found that the dependence of the cross sections on the transverse momenta and the rapidities of the central jet(s) can offer new means of studying the onset of BFKL dynamics.

Azimuthal-angle Observables in Inclusive Three-jet Production

We discuss the impact of corrections beyond the leading-logarithmic accuracy on some recently proposed LHC observables that are based on azimuthal-angle ratios in a kinematical setup that is an extension to the usual one for Mueller-Navelet jets, after requiring an extra tagged jet in central regions of rapidity. The corrections tend to be mild which suggests that these observables are an excellent way to probe the onset of BFKL effects at hadronic colliders.

Inclusive three jet production at the LHC for 7 and 13 TeV collision energies

We discuss briefly a recent study of new observables in LHC inclusive events with three tagged jets. One jet is in the forward direction, the second is in the backward direction and well-separated in rapidity from the first, whereas, the third tagged jet is to be found in more central regions of the detector. Taking into consideration that non-tagged mini-jet emissions are allowed and that they may be accounted for by the BFKL gluon Green function, we project the cross sections on azimuthal-angle components and define suitable ratios based on these projections which can provide several distinct tests of the BFKL dynamics.

Inclusive four-jet production: a study of Multi-Regge kinematics and BFKL observables

A study of differential cross sections for the production of four jets in multi-Regge kinematics is presented, the main focus lying on azimuthal angle dependences. The theoretical setup consists in the jet production from a single BFKL ladder with a convolution of three BFKL Green functions, where two forward/backward jets are always tagged in the final state. Furthermore, the tagging of two further jets in more central regions of the detectors with a relative separation in rapidity from each other is requested. It is found, as result, that the dependence on the transverse momenta and the rapidities of the two central jets can be considered as a distinct signal of the onset of BFKL dynamics.