Search

Precision physics in the Higgs sector has been one of the main challenges of particle physics in the recent years. The pure fixed-order calculations entering the collinear factorization framework, which have been pushed up to next-cube-leading-order, are not able to describe the entire kinematic spectrum. In particular sectors, they have to be necessarily enhanced by all-order resummations. In the so-called semi-hard regime, large energy-type logarithms spoil the perturbative convergence of the series and must be resummed to all orders. This resummation is a core ingredient for a correct description of the inclusive hadroproduction of a forward Higgs boson in the limit of small Bjorken $x$, as well as for a precision study of inclusive forward emissions of a Higgs boson in association with a backward identified object. A complete resummation for these processes can be achieved at the at next-to-leading logarithmic accuracy thanks to the Balitsky-Fadin-Kuraev-Lipatov approach. In the present work we present and discuss a series of recent phenomenological results within a partial next-to-leading accuracy. They include the analysis of rapidity and azimuthal-angle differential rates for Higgs plus jet and Higgs plus charm reactions in forward and ultraforward directions of rapidity at the LHC., Comment: 5 pages, 1 figure, proceedings of the 31st International Workshop on Deep Inelastic Scattering (DIS2024), 8-12 April 2024, Grenoble, France

We present the full next-to-leading order (NLO) result for the impact factor of a forward Higgs boson, obtained in the infinite-top-mass limit, both in the momentum representation and as superposition of the eigenfunctions of the leading-order (LO) BFKL kernel., Comment: 8 pages, 1 Figure. Presented by Michael Fucilla at the 16th International Symposium on Radiative Corrections: Applications of Quantum Field Theory to Phenomenology (RADCOR 2023), Crieff (Scotland), 28 May- 02 June, 2023

It has been recently argued that the inclusive hadroproduction at the LHC of a Higgs boson in association with a jet can be sensitive to the high-energy dynamics. Moreover, the impact of the resummation at FCC energies is expected to be large also in the inclusive cross section for the main Higgs production channel in proton-proton collisions, namely the gluon fusion. As the energy increases, a pure $k_t$-factorization framework or a collinear-factorization approach supplemented by the high-energy resummation are adequate formalisms to describe these processes. In both cases, the fundamental missing ingredient for a next-to-leading logarithmic description is the Higgs boson impact factor. We present the full next-to-leading result for the forward Higgs impact factor, obtained in the infinite top-mass limit, discussing possible future extensions, such as the calculation of the impact factor in the central rapidity region., Comment: 4 pages. Contribution to the 2023 QCD session of the 57th Rencontres de Moriond

Working in the hybrid high-energy/collinear factorization, where the next-to-leading resummation of energy logarithms is combined with collinear parton densities and fragmentation functions, we study observables sensitive to high-energy dynamics in the context of heavy-flavor physics., Comment: 6 pages, 1 figure. Presented by Michael Fucilla at "Diffraction and Low-$x$ 2022", Corigliano Calabro (Italy), September 24-30, 2022

We present a new study on helicity amplitudes and cross sections for the exclusive production of $\rho$ mesons at the EIC in high-energy factorization. In this framework the analytic expression of amplitudes takes the form of a convolution between an off-shell impact factor, depicting the ($\gamma^* \to \rho$) transition, and a nonperturbative density, known as Unintegrated Gluon Distribution (UGD) that encodes information about the proton structure at low $x$ and evolves according to the BFKL equation. We come out with an evidence that observables sensitive to the polarizations of the incoming virtual photon and of the emitted meson allow us to discriminate among different UGD models and to gather quantitative information on the proton content at high energies., Comment: 6 pages, 1 figure. Presented by F.G. Celiberto at DIS2022: XXIX International Workshop on Deep-Inelastic Scattering and Related Subjects, Santiago de Compostela, Spain, May 2-6 2022

We calculate the next-to-leading order correction to the impact factor (vertex) for the production of a forward Higgs boson, obtained in the infinite top-mass limit. We present the result both in the momentum representation and as superposition of the eigenfunctions of the leading-order BFKL kernel. This impact factor is a necessary ingredient for the description of the inclusive hadroproduction of a forward Higgs in the limit of small Bjorken $x$, as well as for the study of inclusive forward emissions of a Higgs boson in association with a backward identified object., Comment: 49 pages, 12 figures

With the advent of TeV-energy colliding machines, such as the Large Hadron Collider (LHC), the possibility has opened up to test predictions of Quantum Chromodynamics (QCD) and, more in general, of the Standard Model (SM), in new, and so far unexplored, kinematical regimes. Among the many reactions that can be investigated at LHC, the Higgs production is one of the most important and challenging for the entire high-energy physics Community. Beside usual studies in the Higgs sector, it has recently been highlighted how differential Higgs distributions can be effectively used as ``stabilizers'' of the high-energy dynamics of QCD. The definition and the study of observables sensitive to high-energy dynamics in Higgs production has the double advantage of (i) allowing us to clearly disentangle the high-energy dynamics from the fixed-order one and (ii) providing us with an auxiliary tool to extend Higgs studies in wider kinematical regimes. In this work, we will show how a general hybrid collinear/high energy factorization can be built up for the inclusive production of a Higgs in association with a jet. Then, we will present some phenomenological analyses that corroborate the underlying assumption that this reaction can be used to investigate the semi-hard regime of QCD. Finally, we will focus on more formal developments, such as the inclusion of subleading corrections to previous studies, via the calculation of the forward next-to-leading order Higgs impact factor., Comment: 6 pages, 1 figures; Presented by M. Fucilla at the Particles and Nuclei International Conference (PANIC 2021), 5-10 September 2021; to be published in the conference proceedings by PoS

Heavy-flavored emissions have been always considered as an excellent channel to test properties of Quantum chromodynamics (QCD) at present and future colliders. Among different regimes, in which heavy-flavor production can be investigated, we focus our attention on the semi-hard one, where $s \gg \{ Q^2 \} \gg \Lambda_{QCD}$ ($s$ is the squared center-of-mass energy, $\{ Q^2 \}$ a (set of) hard scale(s) characteristic of the process and $\Lambda_{QCD}$ the QCD mass scale). Here, we build predictions in a hybrid collinear/high-energy factorization, in which the standard collinear description is supplemented by the Balitsky-Fadin-Kuraev-Lipatov resummation of large energy logarithms. The definition and the study of observables sensitive to high-energy dynamics in the context of heavy-flavor physics has the double advantage of (i) allowing to get a stabilization of the BFKL series under higher-order corrections and (ii) providing us with an auxiliary tool to investigate heavy-flavor production in wider kinematical ranges. Hence, we propose a scientific program on heavy-flavor physics at high-energy with the goal of considering both open (heavy-jet) and bound states ($\Lambda$ baryons, heavy-light mesons and quarkonia)., Comment: 6 pages, 2 figures; Presented by M, Fucilla at the European Physical Society Conference on High Energy Physics (EPS-HEP2021), 26-30 July 2021; to be published in the conference proceedings by PoS

We present recent phenomenological studies, tailored on kinematic configurations typical of current and forthcoming analyses at the LHC, for two novel probe channels of the BFKL resummation of energy logarithms. Particular attention is drawn to the behavior of distributions differential in azimuthal angle and rapidity, where significant high-energy effects are expected., Comment: Submission to SciPost

We investigate the inclusive hadroproduction of a Higgs boson in association with a jet, featuring large transverse momenta and separated by a large rapidity distance. We propose this reaction, that can be studied at the LHC as well as at new-generation colliding machines, as a novel probe channel for the manifestation of the Balitsky-Fadin-Kuraev-Lipatov (BFKL) dynamics. We bring evidence that high-energy resummed distributions in rapidity and transverse momentum exhibit a solid stability under higher-order corrections, thus offering us a faultless chance to gauge the feasibility of precision calculations of these observables at high energies. We come out with the message that future, exhaustive analyses of the inclusive Higgs-boson production, would benefit from the inclusion of high-energy effects in a multi-lateral formalism where distinct resummations are concurrently embodied. We propose these studies with the aim of inspiring synergies with other Communities, and pursuing the goal of widening common horizons in the exploration of the Higgs-physics sector., Comment: 6 pages, 1 figure. Presented by F.G. Celiberto at the European Physical Society Conference on High Energy Physics (EPS-HEP2021), 26-30 July 2021; version accepted for publication in the conference proceedings by PoS

We propose the inclusive semi-hard production, in proton-proton collisions, of two bottom-flavored hadrons, as well as of a single bottom-flavored hadron accompanied by a light jet, as novel channels for the manifestation of stabilization effects of the high-energy resummation under next-to-leading-order corrections. Our formalism relies on a hybrid high-energy and collinear factorization, where the BFKL resummation of leading and next-to-leading energy logarithms is used together with collinear factorization. We present results for cross sections and azimuthal correlations differential in rapidity, which are widely recognized as standard observables where to hunt for distinctive signals of the BFKL dynamics. We propose the study of double differential distributions in the transverse momenta of final-state particles as a common basis to investigate the interplay of different kinds of resummation mechanisms., Comment: 40 pages, 10 figures; improved layout of 3D surface plots in Figs. 7 and 8, small text improvements, added four more reference, version published in Phys. Rev. D

We calculate cross sections for the exclusive diffractive leptoproduction of $\rho$-mesons, $\gamma^*~p~\to~\rho~p$, within the framework of high-energy factorization. Cross sections for longitudinally and transversally polarized mesons are shown. We employ a wide variety of unintegrated gluon distributions available in the literature and compare to HERA data. The resulting cross sections strongly depend on the choice of unintegrated gluon distribution. We also present predictions for the proton target in the kinematics of the Brookhaven EIC., Comment: 21 pages, 8 figures. arXiv admin note: text overlap with arXiv:1808.02395; version published in Eur. Phys. J. C

Using the standard Balitsky-Fadin-Kuraev-Lipatov (BFKL) approach, with partial inclusion of next-to-leading order effects, we propose the inclusive hadroproduction of a Higgs boson and of a jet, featuring large transverse momenta and well separated in rapidity, as a new channel to probe the BFKL dynamics. Predictions are presented for cross-sections and azimuthal angle correlations in different kinematics configurations for the final-state transverse momenta. We find that the large energy scales provided by the emission of a Higgs boson stabilize the BFKL series., Comment: Submission to SciPost

Exclusive emissions of vector mesons in forward directions of rapidity offer us a faultless chance to probe the proton structure at small-$x$. A high-energy factorization formula is established within BFKL, given as the convolution of an impact factor depicting the forward-meson emission and of an unintegrated gluon distribution (UGD) driving the gluon evolution at small-$x$. As a nonperturbative quantity, the UGD is not well known and several models for it exist. We present recent progresses on the study of the exclusive forward $\rho$-meson leptoproduction at HERA and EIC energies, showing how osbervables sensitive to different polarization states of the $\rho$-particle act as discriminators for the existing UGD models., Comment: 8 pages, 1 figure, contribution to the proceedings of the XXVIII International Workshop on Deep Inelastic Scattering and Related Subjects (DIS2021), Stony Brook, New York, USA, 12-16 April, 2021, version accepted for publication on SciPost Physics Proceedings

We propose the inclusive hadroproduction of a heavy-light dijet system, as a new channel for the investigation of high energy QCD. We build up a hybrid factorization that incorporates a partial next-to-leading BFKL resummation inside the standard collinear description of observables. We present a detailed analysis of different observables: cross-section summed over azimuthal angles and differential in rapidity and azimuthal distribution. The stability that these distributions show under higher-order corrections motivates our interest in future studies, doable at new generation colliding machines., Comment: 6 pages, 1 figure, contribution to the proceedings of the XXVIII International Workshop on Deep Inelastic Scattering and Related Subjects (DIS2021), Stony Brook, New York, USA, 12-16 April, 2021, to appear on SciPost Physics Proceedings

We present a study on inclusive emissions of a double $\Lambda_c$ or of a $\Lambda_c$ plus a light-flavored jet system as probe channels in the semi-hard regime of QCD. Our formalism relies on the so-called hybrid high-energy/collinear factorization, where the standard collinear description is supplemented by the $t$-channel resummation \`a la BFKL of energy logarithms up to the next-to-leading accuracy. We make use of the JETHAD modular interface, suited to the analysis of different semi-hard reactions, employing the novel KKSS19 parameterization for the description of parton fragmentation into $\Lambda_c$ baryons. We provide predictions for rapidity distributions and azimuthal correlations, that can be studied at current and forthcoming LHC configurations, hunting for possible stabilizing effects of the high-energy series., Comment: 28 pages, 9 figures; updated references, version published in Eur. Phys. J. C

We propose the study of the inclusive hadroproduction of a heavy-flavored jet in association with a light jet, as a probe channel of strong interactions at high energies. We build up a hybrid factorization that encodes genuine high-energy effects, provided by a partial next-to-leading BFKL resummation, inside the standard collinear structure of the cross section. We present a detailed analysis of different distributions, shaped on kinematic ranges typical of experimental analyses at the Large Hadron Collider, and differential in rapidity, azimuthal angle and transverse momentum. The fair stability that these distributions exhibit under higher-order corrections motivates our interest toward future studies. Here, the hybrid factorization could help to deepen our understanding of heavy-flavor physics in wider kinematic ranges, like the ones accessible at the Electron-Ion Collider., Comment: 32 pages, 10 figures; slight change in the title, four more references added, version published in Phys. Rev. D

We propose the study of the inclusive production of two $\Lambda$ hyperons or a single $\Lambda$-particle in association with a jet, featuring high transverse momenta and large separation in rapidity, as a probe channel of the resummation of energy logarithms in the QCD perturbative series. We give predictions, shaped on kinematic ranges typical of CMS and of the backward CASTOR detector, for cross section and azimuthal-correlation moments between the two emitted objects, showing how considering the tag of $\Lambda$ baryons eases the comparison between theoretical results and experimental data in the phenomenological context of semi-hard reactions., Comment: 23 pages, 6 figures; updated references; slight changes in Eq. (14), updated Section 2.3, added 2 plots (Figs. 6 and 8), version published in Phys. Rev. D

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., Comment: 27 pages, 8 figures; added comparison with fixed-order NLO POWHEG results in Fig. 8, added in new Fig. 9 comparison with large top-mass limit predictions, updated diagram in Fig. 2, version published in Eur. Phys. J. C

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., Comment: 26 pages, 6 figures, one table. arXiv admin note: text overlap with arXiv:1709.10032; added two new references, [71,72], in the first sentence of Section 3.1, version published in Eur. Phys. J. C

Pursuing the goal to single out the validity region of the high-energy resummation, better known as BFKL approach, and to possibly disentangle BFKL effects from the ones coming from a DGLAP-inspired, fixed-order description, new predictions for the forward inclusive hadron-jet production, tailored on the CMS and CASTOR acceptances, are given., Comment: 6 pages, 2 figures; contribution to the proceedings of the XXVII International Workshop on Deep Inelastic Scattering and Related Subjects (DIS2019), Torino, Italy, 8-12 April, 2019; to appear on Proceedings of Science

The inclusive photoproduction of two heavy quarks, separated by a large rapidity interval, is proposed as a new channel for the manifestation of the Balitsky-Fadin-Kuraev-Lipatov (BFKL) dynamics. The extension to the hadroproduction case is also discussed., Comment: 6 pages, 2 figures, 2 tables; contribution to the proceedings of the XXVII International Workshop on Deep Inelastic Scattering and Related Subjects (DIS2019), Torino, Italy, 8-12 April, 2019; to appear on Proceedings of Science

The gluon content of the proton, in the high-energy regime, is embodied by the unintegrated gluon distribution (UGD), which describes the gluon emission probability, with a given longitudinal momentum fraction and transverse momentum. The UGD, formulated within the $\kappa$-factorization approach, has universal validity and several models for it have been proposed so far. We will show that the polarized $\rho$-meson leptoproduction at HERA is a not trivial testfield for discriminating among existing models of UGD., Comment: 6 pages, 4 figures, presented by A.D. Bolognino at "Diffraction & Low-x 2018", Reggio Calabria, Italy, August 26 - September 1, 2018; to be published in the conference proceedings by Acta Phys. Polon. B

We suggest the inclusive detection at the LHC of a light charged hadron and of a jet widely separated in rapidity as a new probe channel for the study of the BFKL resummation. Predictions for cross section and azimuthal correlations, shaped on the CMS and CASTOR acceptances, are presented., Comment: 6 pages, 2 figures; presented by F.G. Celiberto at "Diffraction and Low-x 2018", Reggio Calabria, Italy, August 26 - September 1, 2018; to be published in the conference proceedings by Acta Phys. Polon. B

The inclusive production at the LHC of a charged light hadron and of a jet, featuring a wide separation in rapidity, is suggested as a new probe process for the investigation of the BFKL mechanism of resummation of energy logarithms in the QCD perturbative series. We present some predictions, tailored on the CMS and CASTOR acceptances, for the cross section averaged over the azimuthal angle between the identified jet and hadron and for azimuthal correlations., Comment: 19 pages, 6 figures; few typos corrected and one reference updated during proof reading; version published on Eur. Phys. J. C. arXiv admin note: text overlap with arXiv:1701.05077

The gluon content of the proton is embodied by the unintegrated gluon distribution (UGD), which has universal validity. In literature many models of UGD have been proposed so far. The polarized $\rho$-meson leptoproduction at HERA offers a nowadays unexplored testfield to discriminate among existing models of UGD, via the comparison with theoretical predictions formulated in the $\kappa$-factorization approach., Comment: 6 pages, 3 figures, Talk given at the XIX Frascati Spring School "Bruno Touschek" in nuclear, subnuclear and astroparticle physics, Frascati, 7-11 May 2018

We present here some arguments to support our suggestion that data on the helicity structure for the hard exclusive electroproduction of $\rho$ mesons at HERA (and in possible future high-energy electron-proton colliders) provide useful information to constrain the $\kappa$-shape of the unintegrated gluon distribution in the proton., Comment: 20 pages, 4 figures; version accepted for publication on Eur. Phys. J. C

We present our predictions for the inclusive production of two heavy quark-antiquark pairs, separated by a large rapidity interval, in the collision of (quasi-)real photons at the energies of LEP2 and of some future electron-positron colliders. We include in our calculation the full resummation of leading logarithms in the center-of-mass energy and a partial resummation of the next-to-leading logarithms, within the Balitsky-Fadin-Kuraev-Lipatov (BFKL) approach., Comment: 17 pages, 5 figures, 2 tables; changed some text, removed one figure and added one reference; version accepted for publication in Phys. Lett. B

A study of cross sections and azimuthal correlation moments for the inclusive production of two, light charged hadrons featuring large transverse momenta and well separated in rapidity at LHC energies, including BFKL resummation effects with NLA accuracy, is presented. This reaction shares the same theoretical setup with the well konwn Mueller-Navelet jet production and can be thought of as a new and complementary channel to access the BFKL dynamics at proton colliders., Comment: 6 pages, 1 figure, presented by F.G. Celiberto at the 17th conference on Elastic and Diffractive Scattering, EDS Blois 2017, Prague, Czech Republic, June 26-30, 2017

We give the first phenomenological predictions of cross sections and azimuthal correlations for the inclusive di-hadron production in the full NLA BFKL approach. This process shares the same theoretical framework with the well konwn Mueller-Navelet jet production and can be considered a novel and complementary channel to access the BFKL dynamics at proton colliders., Comment: 11 pages, 4 figures, presented by F.G. Celiberto at the 25th Low-x Meeting, 12-18 June 2017, Bisceglie (Bari, Italy)

The study of the inclusive production of a pair of charged light hadrons (a "dihadron" system) featuring high transverse momenta and well separated in rapidity represents a clear channel for the test of the BFKL dynamics at the Large Hadron Collider (LHC). This process has much in common with the well known Mueller-Navelet jet production; however, hadrons can be detected at much smaller values of the transverse momentum than jets, thus allowing to explore an additional kinematic range, supplementary to the one studied with Mueller-Navelet jets. Furthermore, it makes it possible to constrain not only the parton densities (PDFs) for the initial proton, but also the parton fragmentation functions (FFs) describing the detected hadron in the final state. Here, we present the first full NLA BFKL analysis for cross sections and azimuthal angle correlations for dihadrons produced in the LHC kinematic ranges. We make use of the Brodsky-Lapage-Mackenzie (BLM) optimization method to set the values of the renormalization scale and study the effect of choosing different values for the factorization scale. We also gauge the uncertainty coming from the use of different PDF and FF parametrizations., Comment: 30 pages, 12 figures; added some text and two figures, marginal change in Eq.(5) and in one of the figures; version published on Eur. Phys. J. C

A study of the inclusive production of a pair of hadrons (a "dihadron" system), having high transverse momenta and separated by a large interval of rapidity, is presented. This process has much in common with the widely discussed Mueller--Navelet jet production and can be also used to access the BFKL dynamics at proton colliders. Large contributions enhanced by logarithms of energy can be resummed in perturbation theory within the BFKL formalism in the next-to-leading logarithmic accuracy. The experimental study of dihadron production would provide with an additional clear channel to test the BFKL dynamics. The first theoretical predictions for cross sections and azimuthal angle correlations of the two hadrons produced with LHC kinematics are presented., Comment: 4 pages, 2 figures; presented by F.G. Celiberto at "Diffraction 2016", International Workshop on Diffraction in High-Energy Physics, Acireale (Catania, Sicily), Sept. 2-8, 2016; to be published in the conference proceedings by AIP

A study of the production of Mueller-Navelet jets at 13 TeV LHC is presented, including BFKL resummation effects and investigating three different variants of the BLM scale optimization method. It is shown how the cross section and the azimuthal observables are affected by the exclusion of the events where, for a given rapidity interval between the two jets, one of these is produced in the central region., Comment: 6 pages, 2 figures, presented by F.G. Celiberto at XXIV International Workshop on Deep-Inelastic Scattering and Related Subjects, 11-15 April 2016, DESY Hamburg, Germany

We propose to study at the Large Hadron Collider (LHC) the inclusive production of a pair of hadrons (a "di-hadron" system) in a kinematics where two detected hadrons with high transverse momenta are separated by a large interval of rapidity. This process has much in common with the widely discussed Mueller-Navelet jet production and can also be used to access the dynamics of hard proton-parton interactions in the Regge limit. For both processes large contributions enhanced by logarithms of energy can be resummed in perturbation theory within the Balitsky-Fadin-Kuraev-Lipatov (BFKL) formalism with next-to-leading logarithmic accuracy (NLA). The experimental study of di-hadron production would provide with an additional clear channel to test the BFKL dynamics. We present here the first theoretical predictions for cross sections and azimuthal angle correlations of the di-hadrons produced with LHC kinematics., Comment: 13 pages, 4 figures; some text, one figure and three references added; version accepted for publication on Phys. Rev. D

We study the production of Mueller-Navelet jets at 13 TeV LHC, within collinear factorization and including the BFKL resummation of energy logarithms in the next-to-leading approximation. We calculate several azimuthal correlations for different values of the rapidity separation $Y$ between the two jets and evaluate the effect of excluding those events where, for a given $Y$, one of the two jets is produced in the central region., Comment: 27 pages, 8 figures, 7 tables; added some text and four references; version accepted for publication on Eur. Phys. J. C; arXiv admin note: text overlap with arXiv:1504.08233

The Mueller-Navelet di-jet production process represents an ultimate testfield of pQCD in the high-energy limit. Several experimental analyses carried out so far are in good agreement with theoretical predictions, based on collinear factorization and BFKL resummation of energy logarithms in the next-to-leading approximation, with the CMS experimental data at center-of-mass energy equal to 7 TeV. However, the question if the same data can be described also by fixed-order perturbative approaches has not yet been fully answered. We discuss how the use of partially asymmetric cuts in the transverse momenta of the detected jets allows to discriminate between BFKL-resummed and fixed-order predictions (the latter in the high-energy limit) in observables related with this process at LHC., Comment: 6 pages, 5 figures, presented by F.G. Celiberto at the 16th conference on Elastic and Diffractive Scattering, EDS Blois 2015, Borgo, Corsica, France, June/July 2015

The production of forward jets separated by a large rapidity gap at LHC, the so-called Mueller-Navelet jets, is a fundamental testfield for perturbative QCD in the high-energy limit. Several analyses have already provided with evidence about the compatibility of theoretical predictions, based on collinear factorization and BFKL resummation of energy logarithms in the next-to-leading approximation, with the CMS experimental data at 7 TeV of center-of-mass energy. However, the question if the same data can be described also by fixed-order perturbative approaches has not been yet fully answered. In this paper we provide numerical evidence that the mere use of partially asymmetric cuts in the transverse momenta of the detected jets allows a clear separation between BFKL-resummed and fixed-order predictions in some observables related with the Mueller-Navelet jet production process., Comment: 15 pages, 3 figures, 2 tables; slight change in the title; version to appear on Eur. Phys. J. C. arXiv admin note: text overlap with arXiv:1407.8431

The BFKL approach for the investigation of semihard processes is plagued by large next-to-leading corrections, both in the kernel of the universal BFKL Green's function and in the process-dependent impact factors, as well as by large uncertainties in the renormalization scale setting. All that calls for some optimization procedure of the perturbative series. In this respect, one of the most common methods is the Brodsky-Lepage-Mackenzie (BLM) one, that eliminates the renormalization scale ambiguity by absorbing the non-conformal $\beta_0$-terms into the running coupling. In this paper, we apply BLM scale setting procedure directly to the amplitudes (cross sections) of several semihard processes. We show that, due to the presence of $\beta_0$-terms in the next-to-leading expressions for the impact factors, the optimal renormalization scale is not universal, but depends both on the energy and on the type of process in question., Comment: 21 pages, 4 figures; added a few sentences and two references in the Summary section; version accepted for publication by Phys. Rev. D

We apply the BLM scale setting procedure directly to amplitudes (cross sections) of several semihard processes. It is shown that, due to the presence of $\beta_0$-terms in the NLA results for the impact factors, the obtained optimal renormalization scale is not universal, but depends both on the energy and on the process in question. We illustrate this general conclusion considering the following semihard processes: (i) inclusive production of two forward high-$p_T$ jets separated by large interval in rapidity (Mueller-Navelet jets); (ii) high-energy behavior of the total cross section for highly virtual photons; (iii) forward amplitude of the production of two light vector mesons in the collision of two virtual photons., Comment: 4 pages, one figure; presented by B. Murdaca at "Diffraction 2014", International Workshop on Diffraction in High-Energy Physics, Primosten (Croatia), Sept. 10-16, 2014; to be published in the conference proceedings by AIP

We study the $\gamma^* \gamma^*$ total cross section in the NLA BFKL approach. We have extracted the NLO corrections to the photon impact factor from two recent papers of Balitsky and Chirilli and Chirilli and Kovchegov and used them to build several representations of the total cross section, equivalent within the NLA. We have combined these different representations with two among the most common methods for the optimization of a perturbative series, namely PMS and BLM, and compared their behavior with the energy with the only available experimental data, those from the LEP2 collider., Comment: 4 pages, 2 figures; presented at "Diffraction 2014", Primosten, Sept. 10-16, 2014

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., Comment: 20 pages, 11 figures. Misprints removed in Tables 7 and 8 and in one place of the text; figures and conclusions unchanged; version which incorporates the Erratum accepted by Eur. Phys. J. C

We study the total cross section for the collision of two highly-virtual photons at large energies, taking into account the BFKL resummation of energy logarithms with full next-to-leading accuracy. A necessary ingredient of the calculation, the next-to-leading order impact factor for the photon to photon transition, has been calculated by Balitsky and Chirilli using an approach based on the operator expansion in Wilson lines. We extracted the result for the photon impact factor in the original BFKL calculation scheme comparing the expression for the photon-photon total cross section obtained in BFKL with the one recently derived by Chirilli and Kovchegov in the Wilson-line operator expansion scheme. We perform a detailed numerical analysis, combining different, but equivalent in next-to-leading accuracy, representations of the cross section with various optimization methods of the perturbative series. We compare our results with previous determinations in the literature and with the LEP2 experimental data. We find that the account of Balitsky and Chirilli expression for the photon impact factor reduces the BFKL contribution to the cross section to very small values, making it impossible to describe LEP2 data as the sum of BFKL and leading-order QED quark box contributions., Comment: 20 pages, 8 figures; two sentences and some references added, a few typos removed; version to be published on JHEP

We consider the inclusive process where a pair of identified hadrons having large transverse momenta is produced in high-energy proton-proton collisions. We concentrate on the kinematics where the two identified hadrons in the final state are separated by a large interval of rapidity. In this case the cross section receives large higher-order corrections, which can be resummed in the BFKL approach. We provide a theoretical input for the resummation of such contributions with next-to-leading logarithmic accuracy. This process has much in common with the widely discussed Mueller-Navelet jets production and can be also used to access the BFKL dynamics at proton colliders., Comment: 4 pages, presented at the International Workshop 'Diffraction 2012', Puerto del Carmen (Spain), September 10-15, 2012

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]., Comment: 4 pages, presented at the International Workshop 'Diffraction 2012', Puerto del Carmen (Spain), September 10-15, 2012

We consider within QCD collinear factorization the process $p+p\to {\rm jet} +{\rm jet} +X$, where two forward high-$p_T$ jets are produced with a large separation in rapidity $\Delta y$ (Mueller-Navelet jets). In this case the (calculable) hard part of the reaction receives large higher-order corrections $\sim \alpha^n_s (\Delta y)^n$, which can be accounted for in the BFKL approach with next-to-leading logarithmic accuracy, including contributions $\sim \alpha^n_s (\Delta y)^{n-1}$. We calculate several observables related with this process, using the next-to-leading order jet vertices, recently calculated in the approximation of small aperture of the jet cone in the pseudorapidity-azimuthal angle plane., Comment: 25 pages, 8 figures, 11 tables; some text added in Sections 1 (Introduction) and 4 (Discussion), including a few new references; version to appear on Nuclear Physics B

We calculate in the next-to-leading order the impact factor (vertex) for the production of a forward high-$p_T$ 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., Comment: 4 pages, 4 figures; presented at the XX International Workshop on Deep-Inelastic Scattering and Related Subjects, 26-30 March 2012, University of Bonn

We calculate in next-to-leading order BFKL the jet vertex relevant for the production of Mueller-Navelet jets in proton collisions and of forward jets in deep inelastic scattering. Starting from the definition of the totally inclusive quark and gluon impact factors in the BFKL approach and suitably considering the parton densities and the jet selection functions, we show that an infrared-free result can be found for the jet vertex. Finally we compare our expression for the vertex with the previous calculation of Refs. 1., Comment: 6 pages; presented at the 3rd Young Researchers Workshop "Physics Challenges in the LHC Era", Frascati, May 7 and 10, 2012

We consider within QCD collinear factorization the inclusive process $p+p\to h_1+h_2+X$, where the pair of identified hadrons, $h_1,h_2$, having large transverse momenta is produced in high-energy proton-proton collisions. In particular, we concentrate on the kinematics where the two identified hadrons in the final state are separated by a large interval of rapidity $\Delta y$. In this case the (calculable) hard part of the reaction receives large higher order corrections $\sim \alpha^n_s \Delta y^n$. We provide a theoretical input for the resummation of such contributions with next-to-leading logarithmic accuracy (NLA) in the BFKL approach. Specifically, we calculate in NLA the vertex (impact-factor) for the inclusive production of the identified hadron. This process has much in common with the widely discussed Mueller-Navelet jets production and can be also used to access the BFKL dynamics at proton colliders. Another application of the obtained identified-hadron vertex could be the NLA BFKL description of inclusive forward hadron production in DIS., Comment: 29 pages, 9 figures; corrected few typos and added an acknowledgment; version to be published on JHEP. arXiv admin note: substantial text overlap with arXiv:1202.1082

We consider within QCD collinear factorization the process p+p to jet + jet +X, where two forward high-$p_T$ jets are produced with a large separation in rapidity $\Delta y$ (Mueller-Navelet jets). In this case the (calculable) hard part of the reaction receives large higher-order corrections $\sim \alpha^n_s (\Delta y)^n$, 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-$p_T$ 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., Comment: 32 pages, 4 figures; a few comments and one reference added; a few inessential misprints removed; version to appear on JHEP

We discuss the process $p+p\to h_1+h_2+X$, where the identified hadrons $h_1$ and $h_2$ have large transverse momenta and are produced in high-energy proton-proton collisions with a large rapidity gap between them. In this case the (calculable) hard part of the reaction receives large higher order corrections $\sim \alpha^n_s\ln^n \Delta y$, which can be accounted for in the BFKL approach. Specifically, we describe in the next-to-leading order the calculation of the vertex (impact-factor) for the inclusive production of the identified hadron., Comment: 8 pages, 5 figures; contribution to the proceedings of "Low-x 2011" - Santiago de Compostela (Spain), June 3-7, 2011