Hunting BFKL in semi-hard reactions at the LHC

The agreement between calculations inspired by the resummation of energy logarithms, known as BFKL approach, and experimental data in the semi-hard sector of QCD has become manifest after a wealthy series of phenomenological analyses. However, the contingency that the same data could be concurrently portrayed at the hand of fixed-order, DGLAP-based calculations, has been pointed out recently, but not yet punctually addressed. Taking advantage of the richness of configurations gained by combining the acceptances of CMS and CASTOR detectors, we give results in the full next-to-leading logarithmic approximation of cross sections, azimuthal correlations and azimuthal distributions for three distinct semi-hard processes, each of them featuring a peculiar final-state exclusiveness. Then, making use of disjoint intervals for the transverse momenta of the emitted objects, i.e. $$\kappa $$ κ -windows, we clearly highlight how high-energy resummed and fixed-order driven predictions for semi-hard sensitive observables can be decisively discriminated in the kinematic ranges typical of current and forthcoming analyses at the LHC. The scale-optimization issue is also introduced and explored, while the uncertainty coming from the use of different PDF and FF set is deservedly handled. Finally, a brief overview of , a numerical tool recently developed, suited for the computation of inclusive semi-hard reactions is provided.

High-energy resummed distributions for the inclusive Higgs-plus-jet production at the LHC

The inclusive hadroproduction of a Higgs boson and of a jet, featuring large transverse momenta and well separated in rapidity, is proposed as a novel probe channel for the manifestation of the Balitsky–Fadin–Kuraev–Lipatov (BFKL) dynamics. Using the standard BFKL approach, with partial inclusion of next-to-leading order effects, predictions are presented for azimuthal Higgs-jet correlations and other observables, to be possibly compared with experimental analyses at the LHC and with theoretical predictions obtained in different schemes.

Hermitian separability of BFKL eigenvalue in Bethe–Salpeter approach

We consider the Bethe–Salpeter approach to the BFKL evolution in order to naturally incorporate the property of the Hermitian separability in the BFKL approach. We combine the resulting all order ansatz for the BFKL eigenvalue together with reflection identities for harmonic sums and derive the most complicated term of the next-to-next-to-leading order BFKL eigenvalue in SUSY $$N=4$$ N = 4 . We also suggest a numerical technique for reconstructing the unknown functions in our ansatz from the known results for specific values of confomal spin.

Exclusive vector meson photoproduction at high energies using the discrete BFKL approach

A phenomenological study of the exclusive vector meson photoproduction within the discrete BFKL approach is performed. We estimate the BFKL amplitude in terms of a discrete set of eigenfunctions and use the HERA [Formula: see text] data to constrain the free parameters of the model. As a consequence, we derive a parameter free prediction of the energy dependence of the exclusive vector meson cross section. We demonstrate that the HERA and LHCb data for the exclusive [Formula: see text] and [Formula: see text] photoproduction are quite well describe in a large energy range. However, the model overestimates the precise LHCb data for the smallest values of [Formula: see text], which can be interpreted as an indication of the onset of nonlinear (saturation) effects in the QCD dynamics.

Discrete BFKL approach for photon–photon interactions at high energies

A phenomenological study of the two-photon reaction within the discrete BFKL approach is performed. We estimate the BFKL amplitude in terms of a discrete set of eigenfunctions and use the HERA [Formula: see text] data to constrain the free parameters of the model. As a consequence, we derive a parameter free prediction of the energy dependence of the total [Formula: see text] cross-section and the Bjorken-[Formula: see text] dependence of the photon structure function. We demonstrate that the LEP data is quite well described by the discrete BFKL approach and that experimental data from the future [Formula: see text] colliders can be useful to constrain the description of the QCD dynamics at high energies.

High-energy resummation in heavy-quark pair hadroproduction

The inclusive hadroproduction of two heavy quarks, featuring a large separation in rapidity, is proposed as a novel probe channel of the Balitsky–Fadin–Kuraev–Lipatov (BFKL) approach. In a theoretical setup which includes full resummation of leading logarithms in the center-of-mass energy and partial resummation of the next-to-leading ones, predictions for the cross section and azimuthal coefficients are presented for kinematic configurations typical of current and possible future experimental analyses at the LHC.