# S. V. Goloskokov - BLTP, JINR, Dubna

## Publications Authored By S. V. Goloskokov

**Authors:**The HERMES Collaboration, A. Airapetian, N. Akopov, Z. Akopov, E. C. Aschenauer, W. Augustyniak, S. Belostotski, H. P. Blok, A. Borissov, V. Bryzgalov, G. P. Capitani, G. Ciullo, M. Contalbrigo, W. Deconinck, R. De Leo, E. De Sanctis, M. Düren, G. Elbakian, F. Ellinghaus, L. Felawka, S. Frullani, F. Garibaldi, G. Gavrilov, V. Gharibyan, S. V. Goloskokov, Y. Holler, A. Ivanilov, H. E. Jackson, S. Joosten, R. Kaiser, G. Karyan, A. Kisselev, V. Korotkov, V. Kozlov, P. Kravchenko, P. Kroll, L. Lagamba, L. Lapikás, I. Lehmann, P. Lenisa, W. Lorenzon, S. I. Manaenkov, B. Marianski, H. Marukyan, Y. Miyachi, A. Movsisyan, V. Muccifora, A. Nass, W. -D. Nowak, L. L. Pappalardo, A. Petrosyan, P. E. Reimer, A. R. Reolon, C. Riedl, K. Rith, G. Rosner, A. Rostomyan, D. Ryckbosch, Y. Salomatin, A. Schäfer, G. Schnell, B. Seitz, T. -A. Shibata, V. Shutov, M. Statera, A. Terkulov, R. Truty, A. Trzcinski, M. Tytgat, Y. Van Haarlem, C. Van Hulse, D. Veretennikov, V. Vikhrov, I. Vilardi, S. Yaschenko, B. Zihlmann, P. Zupranski

Exclusive $\rho^0$-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$^2$Read More

We investigate exclusive leptoproduction of $\rho^0$ 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. Read More

We consider the pion pole contribution and transversity effects determined by the $H_T$ and $\bar E_T$ Generalized Parton Distributions (GPDs) which are essential in hard pseudoscalar and vector meson leptoproduction. We investigate spin effects in the $\omega$ and $\rho^0$ reactions. It is shown that the pion pole contribution is very important in the $\omega$ production. Read More

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. Read More

**Affiliations:**

^{1}BLTP, JINR, Dubna

**Category:**High Energy Physics - Phenomenology

We investigate exclusive electroproduction of vector and pseudoscalar mesons at large photon virtuality $Q^2$. These reactions were analyzed within the handbag approach where amplitudes factorize into hard subprocesses and generalized parton distributions (GPDs). The essential role of transversity effects were found in pseudoscalar and light vector meson leptoproduction. Read More

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. Read More

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. Read More

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. Read More

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. Read More

We analyze the electroproduction of pseudoscalar mesons within the handbag approach. To investigate these reactions, we consider the leading-twist contribution together with the transversity twist-3 effects that are crucial in the description of experimental data. Our results on the cross section are in agreement with experiment. Read More

We study the kaon leptoproduction on the basis of the handbag approach. We consider the leading-twist contribution together with the transversity twist-3 effects which were found to be important in the description of pseudo-scalar meson production. We present our predictions for the cross section and spin asymmetries in the kaon leptoproduction. Read More

**Affiliations:**

^{1}JINR Dubna

**Category:**High Energy Physics - Phenomenology

We analyze light meson electroproduction within the handbag model. We study cross sections and spin asymmetries for various mesons. The essential role of the transversity $\tilde H_T$ and $\tilde E_T$ GPDs in electroproduction of pseudoscalar mesons is found. Read More

On the basis of the handbag approach we study cross sections and spin asymmetries for leptoproduction of various vector and pseudoscalar mesons. Our results are in good agrement with high energy experiments. We analyse what information about Generalized Parton Distributions (GPDs) can be obtained from these reactions. Read More

**Affiliations:**

^{1}JINR, Dubna

**Category:**High Energy Physics - Phenomenology

We analyze light meson electroproduction within the handbag model, where the amplitude factorizes into Generelized Parton Distributions (GPDs) and a hard scattering part. The cross sections and spin asymmetries for various vector and pseudoscalar mesons are analyzed. We discuss what information on hadron structure can be obtained from GPDs. Read More

Estimates for electroproduction of pseudoscalar mesons at small values of skewness are presented. Cross sections and asymmetries for these processes are calculated within the handbag approach which is based on factorization in hard parton subprocesses and soft generalized parton distributions (GPDs). The latter are constructed from double distributions. Read More

We analyze light meson electroproduction in the intermediate energy range where the quark contributions are essential. Our calculations are carried out on the basis of the handbag approach. We study cross sections and spin asymmetries for various vector and pseudoscalar mesons. Read More

Light meson electroproduction is analyzed on the basis of the handbag approach. Our results on the cross section and spin effects are in good agrement with experiments at HERA, COMPASS and HERMES energies. Predictions for $A_{UT}$ asymmetry for various reactions are presented. Read More

Light vector meson leptoproduction is analyzed on the basis of the generalized parton distributions. Our results on the cross section and spin effects are in good agrement with experiment at HERA, COMPASS and HERMES energies. Predictions for $A_{UT}$ asymmetry for various reactions are presented. Read More

**Affiliations:**

^{1}JINR,

^{2}Wuppertal Univ.

**Category:**High Energy Physics - Phenomenology

Hard exclusive pi+ electroproduction is investigated within the handbag approach. The prominent role of the pion-pole contribution is demonstrated. It is also shown that the experimental data require a twist-3 effect which ensues from the helicity-flip generalized parton distribution H_T and the twist-3 pion wave function. Read More

The target asymmetry for electroproduction of vector mesons is investigated within the handbag approach. While the generalized parton distribution (GPD) H is taken from a previous analysis of the elctroproduction cross section, we here construct the GPD E from double distributions and constrain it by the Pauli form factors of the nucleon, positivity bounds and sum rules. Predictions for the target asymmetry are given for various vector mesons and discussed how experimental data on the asymmetry will further constrain E and what we may learn about the angular momenta the partons carry. Read More

An analysis of light vector meson photoproduction at small Bjorken $x \leq 0.2$ is done on the basis of the generalized parton distributions (GPDs). Our results on the cross section and spin density matrix elements (SDME) are in good agreement with experiments. Read More

**Authors:**J. Bartels

^{1}, K. Borras

^{2}, M. Diehl

^{3}, H. Jung

^{4}, H. Abramowicz

^{5}, J. Albacete

^{6}, L. Alvarez-Gaume

^{7}, J. Alvarez-Muniz

^{8}, R D. Ball

^{9}, J. Bartels

^{10}, K. Belov, J. Bluemer, J. Bluemlein, A. Bonato, M. Braun, P. Brogueira, G. C Trinchero, R. Conceicao, J-R. Cudell, J Dainton, A. De Roeck, M. Deile, J. Dias de Deus, R. Engel, M C. Espirito Santo, C. Ewerz, R. Fabbri, V. Fadin, P. Falgari, L. Fanò, E. Ferreira, J Forshaw, S. Forte, L. Frankfurt, H. G Dosch, C. Gomez, K. Golec-Biernat, S. Goloskokov, K. Goulianos, G. Gustafson, A. Hamilton, C E. Hyde, M. Islam, D. Ivanov, R. J Luddy, L. Jenkovsky, J. Kaspar, A. Kaidalov, O. Kepka, V. Khoze, M. Klein, B Z. Kopeliovich, A. Kovner, H. Kowalski, M. Kozlov, J. Kretzschmar, K. Kumericki, V. Kundrat, P. L Iafelice, P. Laycock, A. Lengyel, E. Levin, A. Levy, L. Lipatov, M. Lokajicek, J. Londergan, A. Luszczak, V L. Lyuboshitz, D. Mueller, A D. Martin, E. Martynov, S. Marzani, E. Meggiolaro, S. Munier, O. Nachtmann, T. Namsoo, P. Newman, B. Nicolescu, J. Nystrand, K. Passek-Kumericki, T. Pierog, A. Pilkington, M. Pimenta, B. Pire, B Povh, D. Roehrich, C. Royon, M G. Ryskin, A. Sabio Vera, M. Salvadore, C. Sbarra, F. Schuessler, R. Schicker, I. Schmidt, L. Schoeffel, F. Schwennsen, M. Segond, O V. Selyugin, M. Seymour, A. Shoshi, A. Stasto, M. Strikman, B. Surrow, A P. Szczepaniak, A. Szczurek, L. Szymanowski, M. Tasevsky, A. Tavanfar, M. Togawa, A. Tricomi, R. Ulrich, M. Unger, V. V Lyuboshitz, M A. Vazquez-Mozo, G P. Vacca, A. von Manteuffel, M I. Vyazovsky, S. Wallon, G. Watt, C. Weiss, K. Werner, B W. Xiao

**Affiliations:**

^{1}Univ. Hamburg,

^{2}DESY,

^{3}DESY,

^{4}DESY,

^{5}Univ. Hamburg,

^{6}Univ. Hamburg,

^{7}Univ. Hamburg,

^{8}Univ. Hamburg,

^{9}Univ. Hamburg,

^{10}Univ. Hamburg

**Category:**High Energy Physics - Phenomenology

Proceedings of the 12th International Conference on Elastic and Diffractive Scattering (Blois Workshop) - Forward Physics and QCD Read More

We study light vector meson electroproduction at small $x$ within the generalized parton distributions (GPDs) model. The modified perturbative approach is used, where the quark transverse degrees of freedom in the vector meson wave function and hard subprocess are considered. Our results on the cross section and spin observables are in good agreement with experiment Read More

We analyze electroproduction of light vector meson at small Bjorken $x$ within the generalized parton distribution (GPD) approach. Calculation is based on the modified perturbative approach, where the quark transverse degrees of freedom in the hard subprocess are considered. Our results on the cross section are in fair agreement with experiment from HERMES to HERA energies. Read More

**Affiliations:**

^{1}JINR,

^{2}Wuppertal Univ.

**Category:**High Energy Physics - Phenomenology

Electroproduction of light vector mesons is analyzed on the basis of handbag factorization. The required generalized parton distributions are constructed from the CTEQ6 parton distributions with the help of double distributions. The partonic subprocesses are calculated within the modified perturbative approach. Read More

**Affiliations:**

^{1}JINR Dubna,

^{2}Wuppertal Univ.

**Category:**High Energy Physics - Phenomenology

We analyze electroproduction of light vector mesons (V=rho, phi and omega) at small Bjorken-x in the handbag approach in which the process factorizes into general parton distributions and partonic subprocesses. The latter are calculated in the modified perturbative approach where the transverse momenta of the quark and antiquark forming the vector meson are retained and Sudakov suppressions are taken into account. Modeling the generalized parton distributions through double distributions and using simple Gaussian wavefunctions for the vector mesons, we compute the longitudinal cross sections at large photon virtualities. Read More

We analyse spin effects in diffractive vector meson leptoproduction at small $x$ on the basis of the generalized parton distribution (GPD) approach. We take into account quark transverse degrees of freedom in the hard subprocess. We calculate amplitudes for the longitudinally and transversely polarized photons and vector mesons. Read More

We study light vector meson photoproduction at small $x$ on the basis of the generalized parton distribution (GPD). Our results on the cross section and spin density matrix elements (SDME) are in fair agreement with DESY experiments Read More

An analysis of light vector meson photoproduction at small $x$ on the basis of the generalized parton distribution (GPD) approach is presented. Our results on the cross section and spin density matrix elements (SDME) are in fair agreement with DESY experiments. The predicted double spin longitudinal $A_{LL}$ asymmetry is not small at HERMES energies. Read More

**Affiliations:**

^{1}JINR, Dubna,

^{2}Wuppertal Univ.

**Category:**High Energy Physics - Phenomenology

We analyze electroproduction of light vector mesons at small Bjorken-x in an approach that includes the gluonic generalized parton distributions and a partonic subprocess, gamma g --> (q q-bar) g, q q-bar --> V. The subprocess is calculated to lowest order of perturbative QCD taking into account the transverse momenta of the quark and antiquark as well as Sudakov suppressions. Our approach allows to investigate the transition amplitudes for all kind of polarized virtual photons and polarized vector mesons. Read More

Vector meson electroproduction is analyzed within the two-gluon (2G) model and the generalized parton distribution (GPD) approach at small $x$-Bjorken. We demonstrate that 2G and GPD models are not completely equivalent. At the same time, both models are in reasonable agreement with available experimental data on light vector meson electroproduction. Read More

It is reported on an analysis of vector meson leptoproduction at small Bjorken-$x$ and large photon virtuality within an approach that bases on generalized parton distributions (GPDs). This approach leads to results for cross sections and spin density matrix elements for $\rho$ and $\phi$ leptoproduction in fair agreement with experiment. Read More

We discuss quark-antiquark leptoproduction within a QCD two-gluon exchange model at small $x$. The double spin asymmetries for longitudinally polarized leptons and transversely polarized protons in diffractive $Q \bar Q$ production are analysed at eRHIC energies. The predicted $A_{lT}$ asymmetry is large and can be used to obtain information on the polarized generalized gluon distributions in the proton. Read More

We discuss the problem of gauge invariance of the vector meson photoproduction at small $x$ within the two-gluon exchange model. It is found that the gauge invariance is fulfilled if one includes the graphs with higher Fock states in the meson wave function. Obtained results are used to estimate the amplitudes with longitudinal and transverse photon and vector meson polarization. Read More

We study light hadron leptoproduction at small $x$. Vector meson production is analysed in terms of generalized gluon distributions with taking into account the transverse quark motion. Within a two-gluon model the double spin asymmetries for longitudinally polarized leptons and transversely polarized protons in the diffractive $Q \bar Q$ production are investigated. Read More

Deep virtual vector meson leptoproduction at small $\xbj$ is analyzed in the framework of generalized parton distributions. It is shown that the inclusion of transverse degrees of freedom leads to reasonable agreement with the cross section data for light mesons. Read More

We discuss transverse spin effects caused by the spin-flip part of the Pomeron coupling with the proton. The predicted spin asymmetries in proton-proton scattering and QQ production in proton-proton and lepton-proton reactions are not small and can be studied in future polarized experiments. Read More

We discuss diffractive hadron leptoproduction in terms of skewed gluon distributions and within two-gluon exchange model. Connection of the two-gluon approach with skewed gluon distributions is found. The double spin asymmetries for longitudinally polarized leptons and transversely polarized protons in diffractive vector meson and $Q \bar Q$ production at high energies within the two-gluon model is analysed. Read More

We consider double spin asymmetries for longitudinally polarized leptons and transversally polarized protons in diffractive vector meson and $Q \bar Q$ production at high energy range on the basis of two-gluon model. The asymmetry predicted for meson production is quite small. Large asymmetry is expected for $Q \bar Q$ production. Read More

We consider double spin asymmetries for longitudinally polarized leptons and transversely polarized protons in diffractive vector meson and $Q \bar Q$ production at high energies within the two-gluon model. The asymmetry predicted for meson production is quite small. The $A_{lT}$ asymmetry for $Q \bar Q$ production contains two independent terms which are large and can be used to obtain information on the polarized gluon distributions in the proton. Read More

We consider double spin asymmetries for longitudinally polarized leptons and transversally polarized protons in diffractive vector meson and $Q \bar Q$ production for the HERMES energy range on the basis of the two-gluon model. The asymmetry predicted for meson production is quite small. Large asymmetry is expected for $Q \bar Q$ production. Read More

We study the spin-dependent cross-sections of vector meson photoproduction for longitudinally and transversely polarized photons within a QCD- model. The dependence of the $\sigma_T/\sigma_L$ ratio on the photon virtuality and on the meson wave function is analysed. Read More

We study spin asymmetries in diffractive $Q \bar Q$ and vector meson production which are sensitive to the spin-dependent part of the two-gluon-nucleon coupling. It is found that the $A_{ll}$ and $A_{lT}$ asymmetry in diffractive reactions can be used to study polarized gluon distributions of the proton. Read More

Double spin asymmetries in the diffractive $Q \bar Q$ and $J/\Psi$ leptoproduction are discussed. It is shown that the asymmetries for longitudinally polarized lepton and longitudinally or transversely polarized proton can be used to study spin dependent gluon distribution of the proton at small $x$. Read More

Large-distance effects, which lead to the spin-flip part of the hadron -pomeron coupling in QCD -models, are discussed. We study spin asymmetries in exclusive reactions and in diffractive $Q \bar Q$ and vector meson production which are sensitive to the spin-dependent part of the pomeron coupling. Read More

We calculate the double spin asymmetry of the diffractive $Q \bar Q$ and vector meson leptoproduction at COMPASS energies. We analyze dependences of the asymmetry on the structure of the Pomeron-proton coupling. It is shown that it is difficult to study the spin structure of the Pomeron coupling with the proton from the A_{ll} asymmetry. Read More

We consider the dependencies of spin asymmetries in the diffractive $J/\Psi$ and $Q \bar Q$ leptoproduction at HERA energies on the structure of the pomeron-proton coupling. It is shown that it is difficult to study the spin structure of the pomeron coupling with the proton from the $A_{ll}$ asymmetry. The $A_{lT}$ asymmetry is an appropriate object for this investigation. Read More

We calculate the cross section and the $A_{ll}$ asymmetry of the diffractive vector meson leptoproduction for a simple model of the pomeron coupling with the proton. It is found that the sensitivity of the spin--dependent cross section of the diffractive $J/\Psi$ production to the pomeron coupling structure is rather weak. The conclusion is made that it will be difficult to study the structure of the pomeron coupling with the proton in future polarized diffractive experiments on the $J/\Psi$ production. Read More

In this report we calculate the cross section and $A_{ll}$ asymmetry for the diffractive $J/\Psi$ leptoproduction. We study dependences of the asymmetry on the structure of the Pomeron-proton coupling Read More

Large - distance effects in the hadron wave function for the hadron-Pomeron vertex in the QCD -model are discussed. It is shown that they lead to the spin-flip part of the Pomeron coupling which can reach $10 \div 20 %$ with respect to the non-flip part. The obtained structure of the Pomeron coupling modifies spin asymmetries in high--energy diffractive reactions where the Pomeron structure becomes determinative. Read More