arXiv subjects

S. V. Goloskokov

Publications and source records attributed to S. V. Goloskokov.

At least 19 recordsLinked to original sources

arXiv2025

Exclusive $J/Ψ$ Production and Gluon GPDs Effects

Study of exclusive photoproduction of $J/Ψ$ mesons was carried out in a factorization approach. Generalized parton distributions (GPDs) for gluons, which play an important role here, are constructed using the double distribution representation. The obtained cross sections of $J/Ψ$ production in a wide energy range are in good agreement with the experiment. The spin asymmetries in the $J/Ψ$ production were estimated. These calculations were extended to the of $J/Ψ$ mesons production in ultraperipherical $pp$ collisions. It was shown a good agreement of our results with the LHCb data. Predictions have been made for the NICA energy range. The model results can be used to study the gluon GPDs in future colliders.

hep-ph↗

arXiv2025

Mechanical properties of the nucleon from the generalized parton distributions

The proton's internal structure is characterized not only by its charge and magnetic distribution but also by its mechanical and mass properties, which are encoded in the energy-momentum tensor (EMT) of quantum chromodynamics (QCD). These properties provide insights into the spatial distributions of energy, pressure, and shear forces within the proton. Understanding the proton's internal structure, including properties such as its mechanical and mass radii, is essential for unraveling the complex interplay between quarks and gluons that govern its stability and dynamics. In this study, we investigate the gravitational form factors (GFFs) of the proton, particularly the D-term, which encodes key information about the internal stress distribution, pressure, and shear forces within the nucleon. Using a model for skewness-dependent generalized parton distributions constructed from the double-distribution representation, we extract the quark contribution to the $ D(t) $ GFF of the EMT by analyzing available data on Compton form factors. We then employ this extracted GFF to explore the mechanical properties of the proton, including its mechanical and mass radii, as well as the internal pressure and shear force distributions. Our results provide new insights into the proton's internal structure and contribute to the broader understanding of nucleon properties.

hep-ph↗

arXiv2025

Exclusive $J/ψ$ production in proton-proton collisions adopting GPD approach

Exclusive $J/ψ$ production is investigated in proton-proton collisions employing GPD approach with GK model. Three sets gluon density are used to calculate exclusive $J/ψ$ production. The survival factors and equivalent photon approximation are applied to predict the exclusive $J/ψ$ photoproduction in proton-proton collisions. The GPD method prediction gives a good agreement with the experimental data at LHCb. The exclusive $J/ψ$ production is given in proton-proton collisions at RHIC and NICA. These predictions of GPD approach can be employed to estimate the exclusive $J/ψ$ cross sections in future proton-proton collisions.

hep-ph↗

arXiv2024

Study of gluon GPDs in exclusive $J/ψ$ production in electron-proton scattering

Exclusive photoproduction of heavy $J/ψ$ meson is performed within handbag factorization method. The General Parton Distributions (GPDs) for gluons which are an essential ingredient here, are constructed using double distribution (DD) representation. The calculated cross section for few sets of gluon GPDs $H_g$ describe fine $J/ψ$ production experimental data from HERA to LHC energies. Based on this approach we estimate $J/ψ$ spin asymmetries determined by $E_g$ and $\tilde{H}_g$. The GPDs factorization approach can be employed to analyse heavy vector meson production in electron-proton scattering. Investigations of this reactions at future electron-ion colliders in USA and China can give an essential information on gluon GPDs.

hep-ph↗

arXiv2023

Extraction of information on transversity GPDs from $π^0$ and $η$ production on EIC of China

The General Parton Distributions (GPDs) are applied to study the hard Pseudoscalar Meson Production (PMP) at high energies. The PMP amplitudes are be obtained within the GPDs factorization. They are expressed in terms of GPDs convolution functions, which are most essential in PMP reactions. We show that these convolution functions can be extracted from the PMP data in future EIC of China (EicC). Predictions of $π^0$ and $η$ production at typical EicC energies are performed.

hep-ph↗

arXiv2023

Generalized parton distributions at zero skewness

We present a new determination of the generalized parton distributions (GPDs) with their uncertainties at zero skewness, $ ξ=0 $, through a simultaneous analysis of all available experimental data of the nucleon electromagnetic form factors (FFs), nucleon charge and magnetic radii, proton axial FFs (AFFs) and wide-angle Compton scattering (WACS) cross sections for the first time, and we investigate whether there is any tension between these data. This can be considered the most comprehensive analysis of GPDs at $ ξ=0 $ performed so far. We show that such an analysis provides the simultaneous determination of three kinds of GPDs, namely $ H^q $, $ \widetilde{H}^q $ and $ E^q $, considering also the sea-quark contributions. As a result, we find that the inclusion of the WACS and AFF data at larger values of the momentum transfer squared $ Q^2=-t $ can put new constraints on GPDs and change them drastically in some cases. We show that there is a considerable tension between the WACS and the proton magnetic form factor ($ G_M^p $) data, especially at larger values of $ -t $. However, we indicate that the results for the gravitational FF $ M_2 $ and the proton total angular momentum $ J^p $ calculated using the extracted GPDs are in relatively good agreement with the light-cone QCD sum rules (LCSRs) and lattice QCD predictions when the sea-quark contributions are considered and both WACS and $ G_M^p $ data are included in the analyses simultaneously.

hep-ph↗

arXiv2022

Study of transversity GPDs from pseudoscalar mesons production at EIC of China

The exclusive $η$ and $π^0$ electroproduction is studied in the handbag approach based on Generalized Parton Distributions (GPDs) factorization. Predictions of $π^0$ and $η$ mesons are calculated for future Electron-Ion Collider of China (EicC) energy range using obtained cross sections we extract information on the transversity GPDs contributions to these processes.

hep-ph↗

arXiv2022

Exclusive $π^0$ production at EIC of China within handbag approach

The exclusive $π^0$ electroproduction is analyzed within the handbag approach based on Generalized Parton Distributions (GPDs) factorization. We consider the leading-twist contribution together with the transversity effects. It is shown that the transversity, $H_T$ and $\bar E_T$ GPDs are essential in the description of $π^0$ cross section. Predictions for future Electron-Ion Collider of China (EicC) energy range are done. It is found that transversity dominance $σ_T\ggσ_L$, observed at low energies is valid up to EicC energy range.

hep-ph↗

arXiv2022

Determination of the generalized parton distributions through the analysis of the world electron scattering data considering two-photon exchange corrections

We determine the valence generalized parton distributions (GPDs) $ H_v^q $ and $ E_v^q $ with their uncertainties at zero skewness by performing a $ χ^2 $ analysis of the world electron scattering data considering two-photon exchange corrections. The data include a wide and updated range of the electric and magnetic form factors (FFs) of the proton and neutron. As a result, we find that there are no enough constraints on GPDs $ E_v^q $ from FFs data solely though $ H_v^q $ are well constrained. By including the new data of the charge and magnetic radius of the nucleon in the analysis, we show that they put new constraints on the final GPDs, especially on $ E_v^q $. Moreover, we calculate the gravitational FF $ M_2 $ and the total angular momentum $ J^q $ using the extracted GPDs and compare them with the FFs obtained from the light-cone QCD sum rules (LCSR) and Lattice QCD. We show that our results are interestingly in a good consistency with the pure theoretical predictions.

hep-ph↗

arXiv2022

Conceptual design of the Spin Physics Detector

The Spin Physics Detector, a universal facility for studying the nucleon spin structure and other spin-related phenomena with polarized proton and deuteron beams, is proposed to be placed in one of the two interaction points of the NICA collider that is under construction at the Joint Institute for Nuclear Research (Dubna, Russia). At the heart of the project there is huge experience with polarized beams at JINR. The main objective of the proposed experiment is the comprehensive study of the unpolarized and polarized gluon content of the nucleon. Spin measurements at the Spin Physics Detector at the NICA collider have bright perspectives to make a unique contribution and challenge our understanding of the spin structure of the nucleon. In this document the Conceptual Design of the Spin Physics Detector is presented.

hep-ex↗

arXiv2020

Lepton-pair production in hard exclusive hadron-hadron collisions

We investigate lepton-pair production in hard exclusive hadron-hadron collisions. We consider a double handbag (DH) mechanism in which the process amplitude factorizes in hard subprocesses, qq -> qq gamma* and qg -> qg gamma*, and in soft hadron matrix elements parameterized as generalized parton distributions (GPDs). Employing GPDs extracted from exclusive meson electroproduction, we present predictions for the lepton-pair cross section at kinematics typical for the LHC, NICA and FAIR. It turns out from our numerical studies that the quark-gluon subprocess dominates by far, the quark-quark (antiquark) subprocesses are almost negligible.

hep-ph↗

arXiv2017

Ratios of helicity amplitudes for exclusive $ρ^0$ electroproduction on transversely polarized protons

Exclusive $ρ^0$-meson electroproduction is studied by the HERMES experiment, using the 27.6 GeV longitudinally polarized electron/positron beam of HERA and a transversely polarized hydrogen target, in the kinematic region 1.0 GeV$^2$<Q$^2$<7.0 GeV$^2$, 3.0 GeV<W<6.3 GeV, and -t'<0.4 GeV$^2$. Using an unbinned maximum-likelihood method, 25 parameters are extracted. These determine the real and imaginary parts of the ratios of several helicity amplitudes describing $ρ^0$-meson production by a virtual photon. The denominator of those ratios is the dominant amplitude, the nucleon-helicity-non-flip amplitude $F_{0\frac{1}{2}0\frac{1}{2}}$, which describes the production of a longitudinal $ρ^{0}$-meson by a longitudinal virtual photon. The ratios of nucleon-helicity-non-flip amplitudes are found to be in good agreement with those from the previous HERMES analysis. The transverse target polarization allows for the first time the extraction of ratios of a number of nucleon-helicity-flip amplitudes to $F_{0\frac{1}{2}0\frac{1}{2}}$. Results obtained in a handbag approach based on generalized parton distributions taking into account the contribution from pion exchange are found to be in good agreement with these ratios. Within the model, the data favor a positive sign for the $π-ρ$ transition form factor. By also exploiting the longitudinal beam polarization, a total of 71 $ρ^0$ spin-density matrix elements is determined from the extracted 25 parameters, in contrast to only 53 elements as directly determined in earlier analyses.

hep-ex↗

arXiv2016

Amplitudes ratios in $ρ^0$ leptoproductions and GPDs

We investigate exclusive leptoproduction of $ρ^0$ meson. These reactions were analyzed within the factorizing handbag approach. In our model good agreement of observables for light meson production with experimental data in a wide energy range was found. Using the model results we calculate the ratio of different helicity amplitudes for a transversely polarized proton target to the leading twist longitudinal amplitude. Our results are close to the amplitude ratios measured by HERMES.

hep-ph↗

arXiv2015

The exclusive limit of the pion-induced Drell-Yan process

Based on previous studies of hard exclusive leptoproduction of pions in which the essential role of the pion pole and the transversity generalized parton distributions has been pointed out, we present predictions for the four partial cross sections of the exclusive Drell-Yan process, pi^-p -> l^-l^+n.

hep-ph↗

arXiv2014

The pion pole in hard exclusive vector-meson leptoproduction

Exploiting a set of generalized parton distributions (GPDs) derived from analyses of hard exclusive leptoproduction of rho0, phi and pi+ mesons, we investigate the omega spin density matrix elements (SDMEs) recently measured by the HERMES collaboration. It turns out from our study that the pion pole is an important contribution to omega production. It will be treated as a one-particle exchange since its evaluation from the GPD E-tilde considerably underestimates its contribution. As an intermediate step of our analysis we extract the pi-omega transition form factor for photon virtualities less than 4 GeV^2. From our approach we achieve results for the omega SDMEs in good agreement with the HERMES data. The role of the pion pole in exclusive rho0 and phi leptoproduction is discussed too.

hep-ph↗

arXiv2013

Transversity effects in light meson leptoproduction

The light meson electroproduction is analyzed within the handbag approach. We consider the leading-twist contribution together with the transversity effects. We show that the transversity Generalized Parton Distributions (GPDs), $H_T$ and $\bar E_T$ are essential in the description of spin effects in the pseudoscalar and vector meson leptoproduction.

hep-ph↗

arXiv2013

Role of transversity in spin effects in meson leptoproduction

We analyze the light meson leptoproduction within the handbag approach. We show that effects determined by the transversity Generalized Parton Distributions (GPDs), $H_T$ and $\bar E_T$ are essential in the description of pseudoscalar and vector meson leptoproduction.

hep-ph↗

arXiv2013

Transversity in exclusive vector-meson leptoproduction

The role of transversity or helicity-flip generalized parton distributions (GPDs) in leptoproduction of vector mesons is investigated within the framework of the handbag approach. The transversity GPDs in combination with twist-3 meson wave functions, occur in the amplitudes for transitions from a transversely polarized virtual photon to a longitudinal polarized vector meson. The importance of the transversity GPDs can be examined in some of the spin density matrix elements and in transverse target spin asymmetries. Using suitable parametrizations of both helicity-flip and non-flip GPDs, which are essentially taken from our previous papers, we estimate these observables and compare the results with available data.

hep-ph↗