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1. Quantum Systems with Hidden Symmetry. Interbasis Expansions

Author

Mardoyan, L. G., Pogosyan, G. S., Sissakian, A. N., and Ter-Antonyan, V. M.

Subjects
Mathematical Physics
Abstract

This monograph is the English version of the book "Quantum systems with hidden symmetry. Interbasis expansions" published in 2006 by the publishing house FIZMATLIT (Moscow) in Russian. When compiling this version of the book, typos and inaccuracies noted since the release of the Russian edition have been corrected.

Published
2023

2. Leading and Next-to-Leading Order Gluon Polarisation in the Nucleon and Longitudinal Double Spin Asymmetries from Open Charm Muoproduction

Author

Adolph, C., Alekseev, M. G., Alexakhin, V. Yu., Alexandrov, Yu., Alexeev, G. D., Amoroso, A., Antonov, A. A., Austregesilo, A., Badelek, B., Balestra, F., Barth, J., Baum, G., Bedfer, Y., Berlin, A., Bernhard, J., Bertini, R., Bettinelli, M., Bicker, K., Bieling, J., Birsa, R., Bisplinghoff, J., Bordalo, P., Bradamante, F., Braun, C., Bravar, A., Bressan, A., Buechele, M., Burtin, E., Capozza, L., Chiosso, M., Chung, S. U., Cicuttin, A., Crespo, M. L., Torre, S. Dalla, Das, S., Dasgupta, S. S., Dasgupta, S., Denisov, O. Yu., Dhara, L., Donskov, S. V., Doshita, N., Duic, V., Duennweber, W., Dziewiecki, M., Efremov, A., Elia, C., Eversheim, P. D., Eyrich, W., Faessler, M., Ferrero, A., Filin, A., Finger, M., Finger Jr, M., Fischer, H., Franco, C., von Hohenesche, N. du Fresne, Friedrich, J. M., Frolov, V., Garfagnini, R., Gautheron, F., Gavrichtchouk, O. P., Gerassimov, S., Geyer, R., Giorgi, M., Gnesi, I., Gobbo, B., Goertz, S., Grabmueller, S., Grasso, A., Grube, B., Gushterski, R., Guskov, A., Guthoerl, T., Haas, F., von Harrach, D., Heinsius, F. H., Herrmann, F., Hess, C., Hinterberger, F., Horikawa, N., Hoeppner, Ch., d'Hose, N., Huber, S., Ishimoto, S., Ivanov, O., Ivanshin, Yu., Iwata, T., Jahn, R., Jary, V., Jasinski, P., Joosten, R., Kabuss, E., Kang, D., Ketzer, B., Khaustov, G. V., Khokhlov, Yu. A., Kisselev, Yu., Klein, F., Klimaszewski, K., Koblitz, S., Koivuniemi, J. H., Kolosov, V. N., Kondo, K., Koenigsmann, K., Konorov, I., Konstantinov, V. F., Korzenev, A., Kotzinian, A. M., Kouznetsov, O., Kraemer, M., Kroumchtein, Z. V., Kunne, F., Kurek, K., Lauser, L., Lednev, A. A., Lehmann, A., Levorato, S., Lichtenstadt, J., Liska, T., Maggiora, A., Magnon, A., Makke, N., Mallot, G. K., Mann, A., Marchand, C., Martin, A., Marzec, J., Matsuda, T., Meshcheryakov, G., Meyer, W., Michigami, T., Mikhailov, Yu. V., Morreale, A., Mutter, A., Nagaytsev, A., Nagel, T., Nerling, F., Neubert, S., Neyret, D., Nikolaenko, V. I., Nowak, W. -D., Nunes, A. S., Olshevsky, A. G., Ostrick, M., Padee, A., Panknin, R., Panzieri, D., Parsamyan, B., Paul, S., Perevalova, E., Pesaro, G., Peshekhonov, D. V., Piragino, G., Platchkov, S., Pochodzalla, J., Polak, J., Polyakov, V. A., Pretz, J., Quaresma, M., Quintans, C., Rajotte, J. -F., Ramos, S., Rapatsky, V., Reicherz, G., Rocco, E., Rondio, E., Rossiyskaya, N. S., Ryabchikov, D. I., Samoylenko, V. D., Sandacz, A., Sapozhnikov, M. G., Sarkar, S., Savin, I. A., Sbrizzai, G., Schiavon, P., Schill, C., Schlueter, T., Schmidt, A., Schmidt, K., Schmitt, L., Schmieden, H., Schoenning, K., Schopferer, S., Schott, M., Shevchenko, O. Yu., Silva, L., Sinha, L., Sissakian, A. N., Slunecka, M., Smirnov, G. I., Sosio, S., Sozzi, F., Srnka, A., Steiger, L., Stolarski, M., Sulc, M., Sulej, R., Suzuki, H., Sznajder, P., Takekawa, S., Ter Wolbeek, J., Tessaro, S., Tessarotto, F., Tkatchev, L. G., Uhl, S., Uman, I., Vandenbroucke, M., Virius, M., Vlassov, N. V., Wang, L., Weisrock, T., Wilfert, M., Windmolders, R., Wislicki, W., Wollny, H., Zaremba, K., Zavertyaev, M., Zemlyanichkina, E., Ziembicki, M., Zhuravlev, N., and Zvyagin, A.

Subjects
High Energy Physics - Experiment
Abstract

The gluon polarisation in the nucleon was measured using open charm production by scattering 160 GeV/c polarised muons off longitudinally polarised protons or deuterons. The data were taken by the COMPASS collaboration between 2002 and 2007. A detailed account is given of the analysis method that includes the application of neural networks. Several decay channels of D^0 mesons are investigated. Longitudinal spin asymmetries of the D meson production cross-sections are extracted in bins of D^0 transverse momentum and energy. At leading order QCD accuracy the average gluon polarisation is determined as (Delta g/G)^LO=-0.06 +/- 0.21 (stat.) +/- 0.08 (syst.) at the scale ~13 (GeV/c)^2 and an average gluon momentum fraction ~ 0.11. For the first time, the average gluon polarisation is also obtained at next-to-leading order QCD accuracy as (Delta g/G)^NLO = -0.13 +/- 0.15 (stat.) +/- 0.15 (syst.) at the scale ~ 13 (\GeV/c)^2 and ~ 0.20., Comment: 35 pages, 13 figures and 13 tables

Published
2012
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3. D* and D Meson Production in Muon Nucleon Interactions at 160 GeV/c

Author

Adolph, C., Alekseev, M. G., Alexakhin, V. Yu., Alexandrov, Yu., Alexeev, G. D., Amoroso, A., Antonov, A. A., Austregesilo, A., Badelek, B., Balestra, F., Barth, J., Baum, G., Bedfer, Y., Berlin, A., Bernhard, J., Bertini, R., Bettinelli, M., Bicker, K., Bieling, J., Birsa, R., Bisplinghoff, J., Bordalo, P., Bradamante, F., Braun, C., Bravar, A., Bressan, A., Buechele, M., Burtin, E., Capozza, L., Chiosso, M., Chung, S. U., Cicuttin, A., Crespo, M. L., Torre, S. Dalla, Das, S., Dasgupta, S. S., Dasgupta, S., Denisov, O. Yu., Dhara, L., Donskov, S. V., Doshita, N., Duic, V., Duennweber, W., Dziewiecki, M., Efremov, A., Elia, C., Eversheim, P. D., Eyrich, W., Faessler, M., Ferrero, A., Filin, A., Finger, M., Finger Jr, M., Fischer, H., Franco, C., von Hohenesche, N. du Fresne, Friedrich, J. M., Frolov, V., Garfagnini, R., Gautheron, F., Gavrichtchouk, O. P., Gerassimov, S., Geyer, R., Giorgi, M., Gnesi, I., Gobbo, B., Goertz, S., Grabmueller, S., Grasso, A., Grube, B., Gushterski, R., Guskov, A., Guthoerl, T., Haas, F., von Harrach, D., Heinsius, F. H., Herrmann, F., Hess, C., Hinterberger, F., Horikawa, N., Hoeppner, Ch., d'Hose, N., Huber, S., Ishimoto, S., Ivanov, O., Ivanshin, Yu., Iwata, T., Jahn, R., Jary, V., Jasinski, P., Joosten, R., Kabuss, E., Kang, D., Ketzer, B., Khaustov, G. V., Khokhlov, Yu. A., Kisselev, Yu., Klein, F., Klimaszewski, K., Koblitz, S., Koivuniemi, J. H., Kolosov, V. N., Kondo, K., Koenigsmann, K., Konorov, I., Konstantinov, V. F., Korzenev, A., Kotzinian, A. M., Kouznetsov, O., Kraemer, M., Kroumchtein, Z. V., Kunne, F., Kurek, K., Lauser, L., Lednev, A. A., Lehmann, A., Levorato, S., Lichtenstadt, J., Liska, T., Maggiora, A., Magnon, A., Makke, N., Mallot, G. K., Mann, A., Marchand, C., Martin, A., Marzec, J., Matsuda, T., Meshcheryakov, G., Meyer, W., Michigami, T., Mikhailov, Yu. V., Morreale, A., Mutter, A., Nagaytsev, A., Nagel, T., Nerling, F., Neubert, S., Neyret, D., Nikolaenko, V. I., Nowak, W. -D., Nunes, A. S., Olshevsky, A. G., Ostrick, M., Padee, A., Panknin, R., Panzieri, D., Parsamyan, B., Paul, S., Perevalova, E., Pesaro, G., Peshekhonov, D. V., Piragino, G., Platchkov, S., Pochodzalla, J., Polak, J., Polyakov, V. A., Pretz, J., Quaresma, M., Quintans, C., Rajotte, J. -F., Ramos, S., Rapatsky, V., Reicherz, G., Rocco, E., Rondio, E., Rossiyskaya, N. S., Ryabchikov, D. I., Samoylenko, V. D., Sandacz, A., Sapozhnikov, M. G., Sarkar, S., Savin, I. A., Sbrizzai, G., Schiavon, P., Schill, C., Schlueter, T., Schmidt, A., Schmidt, K., Schmitt, L., Schmieden, H., Schoenning, K., Schopferer, S., Schott, M., Shevchenko, O. Yu., Silva, L., Sinha, L., Sissakian, A. N., Slunecka, M., Smirnov, G. I., Sosio, S., Sozzi, F., Srnka, A., Steiger, L., Stolarski, M., Sulc, M., Sulej, R., Suzuki, H., Sznajder, P., Takekawa, S., Ter Wolbeek, J., Tessaro, S., Tessarotto, F., Tkatchev, L. G., Uhl, S., Uman, I., Vandenbroucke, M., Virius, M., Vlassov, N. V., Wang, L., Weisrock, T., Wilfert, M., Windmolders, R., Wislicki, W., Wollny, H., Zaremba, K., Zavertyaev, M., Zemlyanichkina, E., Ziembicki, M., Zhuravlev, N., and Zvyagin, A.

Subjects
High Energy Physics - Experiment
Abstract

The production of D* and D mesons in inelastic scattering of 160 GeV/c muons off a ^6LiD target has been investigated with the COMPASS spectrometer at CERN for 0.003 (GeV/c)^2 < Q^2 < 10 (GeV/c)^2 and 3x10^-5< x_Bj < 0.1. The study is based on 8100 events where a D^0 or anti D^0 is detected subsequently to a D*+ or D*- decay, and on 34000 events, where only a D^0 or anti D^0 is detected. Kinematic distributions of D*, D and K*_2 are given as a function of their energy E, transverse momentum p_T, energy fraction z, and of the virtual photon variables nu, Q^2 and x_Bj. Semi-inclusive differential D* production cross-sections are compared with theoretical predictions for D* production via photon-gluon fusion into open charm. The total observed production cross-section for D*+/- mesons with laboratory energies between 22 and 86 GeV is 1.9 nb. Significant cross-section asymmetries are observed between D*+ and D*- production for nu<40 GeV and z>0.6., Comment: 22 pages, 12 figures and 2 tables

Published
2012
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4. Exclusive rho^0 muoproduction on transversely polarised protons and deuterons

Author

Adolph, C., Alekseev, M. G., Alexakhin, V. Yu., Alexandrov, Yu., Alexeev, G. D., Amoroso, A., Antonov, A. A., Austregesilo, A., Badełek, B., Balestra, F., Barth, J., Baum, G., Bedfer, Y., Bernhard, J., Bertini, R., Bettinelli, M., Bicker, K., Bieling, J., Birsa, R., Bisplinghoff, J., Bordalo, P., Bradamante, F., Braun, C., Bravar, A., Bressan, A., Büchele, M., Burtin, E., Capozza, L., Chiosso, M., Chung, S. U., Cicuttin, A., Crespo, M. L., Torre, S. Dalla, Das, S., Dasgupta, S. S., Dasgupta, S., Denisov, O. Yu., Dhara, L., Donskov, S. V., Doshita, N., Duic, V., Dünnweber, W., Dziewiecki, M., Efremov, A., Elia, C., Eversheim, P. D., Eyrich, W., Faessler, M., Ferrero, A., Filin, A., Finger, M., Finger Jr, M., Fischer, H., Franco, C., von Hohenesche, N. du Fresne, Friedrich, J. M., Frolov, V., Garfagnini, R., Gautheron, F., Gavrichtchouk, O. P., Gerassimov, S., Geyer, R., Giorgi, M., Gnesi, I., Gobbo, B., Goertz, S., Grabmüller, S., Grasso, A., Grube, B., Gushterski, R., Guskov, A., Guthörl, T., Haas, F., von Harrach, D., Heinsius, F. H., Herrmann, F., Heß, C., Hinterberger, F., Horikawa, N., Höppner, Ch., d'Hose, N., Ishimoto, S., Ivanov, O., Ivanshin, Yu., Iwata, T., Jahn, R., Jary, V., Jasinski, P., Jegou, G., Joosten, R., Kabuß, E., Kang, D., Ketzer, B., Khaustov, G. V., Khokhlov, Yu. A., Kisselev, Yu., Klein, F., Klimaszewski, K., Koblitz, S., Koivuniemi, J. H., Kolosov, V. N., Kondo, K., Königsmann, K., Konorov, I., Konstantinov, V. F., Korzenev, A., Kotzinian, A. M., Kouznetsov, O., Krämer, M., Kroumchtein, Z. V., Kunne, F., Kurek, K., Lauser, L., Lednev, A. A., Lehmann, A., Levorato, S., Lichtenstadt, J., Liska, T., Maggiora, A., Magnon, A., Makke, N., Mallot, G. K., Mann, A., Marchand, C., Martin, A., Marzec, J., Matsuda, T., Meshcheryakov, G., Meyer, W., Michigami, T., Mikhailov, Yu. V., Moinester, M. A., Morreale, A., Mutter, A., Nagaytsev, A., Nagel, T., Negrini, T., Nerling, F., Neubert, S., Neyret, D., Nikolaenko, V. I., Nowak, W. -D., Nunes, A. S., Olshevsky, A. G., Ostrick, M., Padee, A., Panknin, R., Panzieri, D., Parsamyan, B., Paul, S., Perevalova, E., Pesaro, G., Peshekhonov, D. V., Piragino, G., Platchkov, S., Pochodzalla, J., Polak, J., Polyakov, V. A., Pretz, J., Quaresma, M., Quintans, C., Rajotte, J. -F., Ramos, S., Rapatsky, V., Reicherz, G., Richter, A., Rocco, E., Rondio, E., Rossiyskaya, N. S., Ryabchikov, D. I., Samoylenko, V. D., Sandacz, A., Sapozhnikov, M. G., Sarkar, S., Savin, I. A., Sbrizzai, G., Schiavon, P., Schill, C., Schlüter, T., Schmidt, K., Schmitt, L., Schönning, K., Schopferer, S., Schott, M., Schröder, W., Shevchenko, O. Yu., Silva, L., Sinha, L., Sissakian, A. N., Slunecka, M., Smirnov, G. I., Sosio, S., Sozzi, F., Srnka, A., Steiger, L., Stolarski, M., Sulc, M., Sulej, R., Suzuki, H., Sznajder, P., Takekawa, S., Ter Wolbeek, J., Tessaro, S., Tessarotto, F., Tkatchev, L. G., Uhl, S., Uman, I., Vandenbroucke, M., Virius, M., Vlassov, N. V., Wang, L., Wilfert, M., Windmolders, R., Wiślicki, W., Wollny, H., Zaremba, K., Zavertyaev, M., Zemlyanichkina, E., Ziembicki, M., Zhuravlev, N., and Zvyagin, A.

Subjects
High Energy Physics - Experiment
Abstract

The transverse target spin azimuthal asymmetry A_UT in hard exclusive production of rho^0 mesons was measured at COMPASS by scattering 160 GeV/c muons off transversely polarised protons and deuterons. The measured asymmetry is sensitive to the nucleon helicity-flip generalised parton distributions E^q, which are related to the orbital angular momentum of quarks in the nucleon. The Q^2, x_B and p_t^2 dependence of A_UT is presented in a wide kinematic range. Results for deuterons are obtained for the first time. The measured asymmetry is small in the whole kinematic range for both protons and deuterons, which is consistent with the theoretical interpretation that contributions from GPDs E^u and E^d approximately cancel., Comment: 20 pages, 9 figures and 4 tables, updated author list

Published
2012
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5. Experimental investigation of transverse spin asymmetries in muon-p SIDIS processes: Sivers asymmetries

Author

Adolph, C., Alekseev, M. G., Alexakhin, V. Yu., Alexandrov, Yu., Alexeev, G. D., Amoroso, A., Antonov, A. A., Austregesilo, A., Badelek, B., Balestra, F., Barth, J., Baum, G., Bedfer, Y., Bernhard, J., Bertini, R., Bettinelli, M., Bicker, K., Bieling, J., Birsa, R., Bisplinghoff, J., Bordalo, P., Bradamante, F., Braun, C., Bravar, A., Bressan, A., Burtin, E., Capozza, L., Chiosso, M., Chung, S. U., Cicuttin, A., Crespo, M. L., Torre, S. Dalla, Das, S., Dasgupta, S. S., Dasgupta, S., Denisov, O. Yu., Dhara, L., Donskov, S. V., Doshita, N., Duic, V., Duennweber, W., Dziewiecki, M., Efremov, A., Elia, C., Eversheim, P. D., Eyrich, W., Faessler, M., Ferrero, A., Filin, A., Finger, M., Finger jr., M., Fischer, H., Franco, C., von Hohenesche, N. du Fresne, Friedrich, J. M., Frolov, V., Garfagnini, R., Gautheron, F., Gavrichtchouk, O. P., Gerassimov, S., Geyer, R., Giorgi, M., Gnesi, I., Gobbo, B., Goertz, S., Grabmueller, S., Grasso, A., Grube, B., Gushterski, R., Guskov, A., Guthoerl, T., Haas, F., von Harrach, D., Heinsius, F. H., Herrmann, F., Hess, C., Hinterberger, F., Horikawa, N., Hoeppner, Ch., d'Hose, N., Ishimoto, S., Ivanov, O., Ivanshin, Yu., Iwata, T., Jahn, R., Jary, V., Jasinski, P., Joosten, R., Kabuss, E., Kang, D., Ketzer, B., Khaustov, G. V., Khokhlov, Yu. A., Kisselev, Yu., Klein, F., Klimaszewski, K., Koblitz, S., Koivuniemi, J. H., Kolosov, V. N., Kondo, K., Koenigsmann, K., Konorov, I., Konstantinov, V. F., Korzenev, A., Kotzinian, A. M., Kouznetsov, O., Kraemer, M., Kroumchtein, Z. V., Kunne, F., Kurek, K., Lauser, L., Lednev, A. A., Lehmann, A., Levorato, S., Lichtenstadt, J., Liska, T., Maggiora, A., Magnon, A., Makke, N., Mallot, G. K., Mann, A., Marchand, C., Martin, A., Marzec, J., Matsuda, T., Meshcheryakov, G., Meyer, W., Michigami, T., Mikhailov, Yu. V., Moinester, M. A., Morreale, A., Mutter, A., Nagaytsev, A., Nagel, T., Negrini, T., Nerling, F., Neubert, S., Neyret, D., Nikolaenko, V. I., Nowak, W. D., Nunes, A. S., Olshevsky, A. G., Ostrick, M., Padee, A., Panknin, R., Panzieri, D., Parsamyan, B., Paul, S., Perevalova, E., Pesaro, G., Peshekhonov, D. V., Piragino, G., Platchkov, S., Pochodzalla, J., Polak, J., Polyakov, V. A., Pretz, J., Quaresma, M., Quintans, C., Rajotte, J. -F., Ramos, S., Rapatsky, V., Reicherz, G., Richter, A., Rocco, E., Rondio, E., Rossiyskaya, N. S., Ryabchikov, D. I., Samoylenko, V. D., Sandacz, A., Sapozhnikov, M. G., Sarkar, S., Savin, I. A., Sbrizzai, G., Schiavon, P., Schill, C., Schlueter, T., Schmidt, K., Schmitt, L., Schoenning, K., Schopferer, S., Schott, M., Schroeder, W., Shevchenko, O. Yu., Silva, L., Sinha, L., Sissakian, A. N., Slunecka, M., Smirnov, G. I., Sosio, S., Sozzi, F., Srnka, A., Steiger, L., Stolarski, M., Sulc, M., Sulej, R., Suzuki, H., Sznajder, P., Takekawa, S., Ter Wolbeek, J., Tessaro, S., Tessarotto, F., Tkatchev, L. G., Uhl, S., Uman, I., Vandenbroucke, M., Virius, M., Vlassov, N. V., Wang, L., Wilfert, M., Windmolders, R., Wislicki, W., Wollny, H., Zaremba, K., Zavertyaev, M., Zemlyanichkina, E., Ziembicki, M., Zhuravlev, N., and Zvyagin, A.

Subjects
High Energy Physics - Experiment
Abstract

The COMPASS Collaboration at CERN has measured the transverse spin azimuthal asymmetry of charged hadrons produced in semi-inclusive deep inelastic scattering using a 160 GeV positive muon beam and a transversely polarised NH_3 target. The Sivers asymmetry of the proton has been extracted in the Bjorken x range 0.003 0.03. The asymmetry is different from zero and positive also in the low x region, where sea-quarks dominate. The kinematic dependence of the asymmetry has also been investigated and results are given for various intervals of hadron and virtual photon fractional energy. In contrast to the case of the Collins asymmetry, the results on the Sivers asymmetry suggest a strong dependence on the four-momentum transfer to the nucleon, in agreement with the most recent calculations., Comment: 11 pages, 6 figures

Published
2012
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6. Experimental investigation of transverse spin asymmetries in muon-p SIDIS processes: Collins asymmetries

Author

Adolph, C., Alekseev, M. G., Alexakhin, V. Yu., Alexandrov, Yu., Alexeev, G. D., Amoroso, A., Antonov, A. A., Austregesilo, A., Badelek, B., Balestra, F., Barth, J., Baum, G., Bedfer, Y., Bernhard, J., Bertini, R., Bettinelli, M., Bicker, K., Bieling, J., Birsa, R., Bisplinghoff, J., Bordalo, P., Bradamante, F., Braun, C., Bravar, A., Bressan, A., Burtin, E., Capozza, L., Chiosso, M., Chung, S. U., Cicuttin, A., Crespo, M. L., Torre, S. Dalla, Das, S., Dasgupta, S. S., Dasgupta, S., Denisov, O. Yu., Dhara, L., Donskov, S. V., Doshita, N., Duic, V., Duennweber, W., Dziewiecki, M., Efremov, A., Elia, C., Eversheim, P. D., Eyrich, W., Faessler, M., Ferrero, A., Filin, A., Finger, M., Finger jr., M., Fischer, H., Franco, C., von Hohenesche, N. du Fresne, Friedrich, J. M., Frolov, V., Garfagnini, R., Gautheron, F., Gavrichtchouk, O. P., Gerassimov, S., Geyer, R., Giorgi, M., Gnesi, I., Gobbo, B., Goertz, S., Grabmueller, S., Grasso, A., Grube, B., Gushterski, R., Guskov, A., Guthoerl, T., Haas, F., von Harrach, D., Heinsius, F. H., Herrmann, F., Hess, C., Hinterberger, F., Horikawa, N., Hoeppner, Ch., d'Hose, N., Ishimoto, S., Ivanov, O., Ivanshin, Yu., Iwata, T., Jahn, R., Jary, V., Jasinski, P., Joosten, R., Kabuss, E., Kang, D., Ketzer, B., Khaustov, G. V., Khokhlov, Yu. A., Kisselev, Yu., Klein, F., Klimaszewski, K., Koblitz, S., Koivuniemi, J. H., Kolosov, V. N., Kondo, K., Koenigsmann, K., Konorov, I., Konstantinov, V. F., Korzenev, A., Kotzinian, A. M., Kouznetsov, O., Kraemer, M., Kroumchtein, Z. V., Kunne, F., Kurek, K., Lauser, L., Lednev, A. A., Lehmann, A., Levorato, S., Lichtenstadt, J., Liska, T., Maggiora, A., Magnon, A., Makke, N., Mallot, G. K., Mann, A., Marchand, C., Martin, A., Marzec, J., Matsuda, T., Meshcheryakov, G., Meyer, W., Michigami, T., Mikhailov, Yu. V., Moinester, M. A., Morreale, A., Mutter, A., Nagaytsev, A., Nagel, T., Negrini, T., Nerling, F., Neubert, S., Neyret, D., Nikolaenko, V. I., Nowak, W. D., Nunes, A. S., Olshevsky, A. G., Ostrick, M., Padee, A., Panknin, R., Panzieri, D., Parsamyan, B., Paul, S., Perevalova, E., Pesaro, G., Peshekhonov, D. V., Piragino, G., Platchkov, S., Pochodzalla, J., Polak, J., Polyakov, V. A., Pretz, J., Quaresma, M., Quintans, C., Rajotte, J. -F., Ramos, S., Rapatsky, V., Reicherz, G., Richter, A., Rocco, E., Rondio, E., Rossiyskaya, N. S., Ryabchikov, D. I., Samoylenko, V. D., Sandacz, A., Sapozhnikov, M. G., Sarkar, S., Savin, I. A., Sbrizzai, G., Schiavon, P., Schill, C., Schlueter, T., Schmidt, K., Schmitt, L., Schoenning, K., Schopferer, S., Schott, M., Schroeder, W., Shevchenko, O. Yu., Silva, L., Sinha, L., Sissakian, A. N., Slunecka, M., Smirnov, G. I., Sosio, S., Sozzi, F., Srnka, A., Steiger, L., Stolarski, M., Sulc, M., Sulej, R., Suzuki, H., Sznajder, P., Takekawa, S., Ter Wolbeek, J., Tessaro, S., Tessarotto, F., Tkatchev, L. G., Uhl, S., Uman, I., Vandenbroucke, M., Virius, M., Vlassov, N. V., Wang, L., Wilfert, M., Windmolders, R., Wislicki, W., Wollny, H., Zaremba, K., Zavertyaev, M., Zemlyanichkina, E., Ziembicki, M., Zhuravlev, N., and Zvyagin, A.

Subjects
High Energy Physics - Experiment
Abstract

The COMPASS Collaboration at CERN has measured the transverse spin azimuthal asymmetry of charged hadrons produced in semi-inclusive deep inelastic scattering using a 160 GeV positive muon beam and a transversely polarised NH_3 target. The Collins asymmetry of the proton was extracted in the Bjorken x range 0.003

Published
2012
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7. Transverse spin effects in hadron-pair production from semi-inclusive deep inelastic scattering

Author

Adolph, C., Alekseev, M. G., Alexakhin, V. Yu., Alexandrov, Yu., Alexeev, G. D., Amoroso, A., Antonov, A. A., Austregesilo, A., Badellek, B., Balestra, F., Barth, J., Baum, G., Bedfer, Y., Bernhard, J., Bertini, R., Bettinelli, M., Bicker, K., Bieling, J., Birsa, R., Bisplinghoff, J., Bordalo, P., Bradamante, F., Braun, C., Bravar, A., Bressan, A., Burtin, E., Chaberny, D., Chiosso, M., Chung, S. U., Cicuttin, A., Crespo, M. L., Torre, S. Dalla, Das, S., Dasgupta, S. S., Denisov, O. Yu., Dhara, L., Donskov, S. V., Doshita, N., Duic, V., Duennweber, W., Dziewiecki, M., Efremov, A., Elia, C., Eversheim, P. D., Eyrich, W., Faessler, M., Ferrero, A., Filin, A., Finger, M., Finger Jr, M., Fischer, H., Franco, C., von Hohenesche, N. du Fresne, Friedrich, J. M., Garfagnini, R., Gautheron, F., Gavrichtchouk, O. P., Gazda, R., Gerassimov, S., Geyer, R., Giorgi, M., Gnesi, I., Gobbo, B., Goertz, S., Grabmueller, S., Grasso, A., Grube, B., Gushterski, R., Guskov, A., Guthoerl, T., Haas, F., von Harrach, D., Heinsius, F. H., Herrmann, F., Hess, C., Hinterberger, F., Horikawa, N., Hoeppner, Ch., d'Hose, N., Huber, S., Ishimoto, S., Ivanov, O., Ivanshin, Yu., Iwata, T., Jahn, R., Jasinski, P., Joosten, R., Kabuss, E., Kang, D., Ketzer, B., Khaustov, G. V., Khokhlov, Yu. A., Kisselev, Yu., Klein, F., Klimaszewski, K., Koblitz, S., Koivuniemi, J. H., Kolosov, V. N., Kondo, K., Koenigsmann, K., Konorov, I., Konstantinov, V. F., Korzenev, A., Kotzinian, A. M., Kouznetsov, O., Kraemer, M., Kroumchtein, Z. V., Kunne, F., Kurek, K., Lauser, L., Lednev, A. A., Lehmann, A., Levorato, S., Lichtenstadt, J., Maggiora, A., Magnon, A., Makke, N., Mallot, G. K., Mann, A., Marchand, C., Martin, A., Marzec, J., Massmann, F., Matsuda, T., Meyer, W., Michigami, T., Mielech, A., Mikhailov, Yu. V., Moinester, M. A., Morreale, A., Mutter, A., Nagaytsev, A., Nagel, T., Negrini, T., Nerling, F., Neubert, S., Neyret, D., Nikolaenko, V. I., Nowak, W. D., Nunes, A. S., Olshevsky, A. G., Ostrick, M., Padee, A., Panknin, R., Panzieri, D., Parsamyan, B., Paul, S., Perevalova, E., Pesaro, G., Peshekhonov, D. V., Piragino, G., Platchkov, S., Pochodzalla, J., Polak, J., Polyakov, V. A., Pontecorvo, G., Pretz, J., Quaresma, M., Quintans, C., Rajotte, J. -F., Ramos, S., Rapatsky, V., Reicherz, G., Richter, A., Rocco, E., Rondio, E., Rossiyskaya, N. S., Ryabchikov, D. I., Samoylenko, V. D., Sandacz, A., Sapozhnikov, M. G., Sarkar, S., Savin, I. A., Sbrizzai, G., Schiavon, P., Schill, C., Schlueter, T., Schmidt, K., Schmitt, L., Schoenning, K., Schopferer, S., Schott, M., Shevchenko, O. Yu., Silva, L., Sinha, L., Sissakian, A. N., Slunecka, M., Smirnov, G. I., Sosio, S., Sozzi, F., Srnka, A., Stolarski, M., Sulc, M., Sulej, R., Sznajder, P., Takekawa, S., Ter Wolbeek, J., Tessaro, S., Tessarotto, F., Tkatchev, L. G., Uhl, S., Uman, I., Vandenbroucke, M., Virius, M., Vlassov, N. V., Vossen, A., Wang, L., Windmolders, R., Wislicki, W., Wollny, H., Zaremba, K., Zavertyaev, M., Zemlyanichkina, E., Ziembicki, M., Zhuravlevd, N., and Zvyagin, A.

Subjects
High Energy Physics - Experiment
Abstract

First measurements of azimuthal asymmetries in hadron-pair production in deep-inelastic scattering of muons on transversely polarised ^6LiD (deuteron) and NH_3 (proton) targets are presented. The data were taken in the years 2002-2004 and 2007 with the COMPASS spectrometer using a muon beam of 160 GeV/c at the CERN SPS. The asymmetries provide access to the transversity distribution functions, without involving the Collins effect as in single hadron production. The sizeable asymmetries measured on the NH_ target indicate non-vanishing u-quark transversity and two-hadron interference fragmentation functions. The small asymmetries measured on the ^6LiD target can be interpreted as indication for a cancellation of u- and d-quark transversities., Comment: 13 pages, 4 figures, updated to the published version

Published
2012
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8. Leading order determination of the gluon polarisation from DIS events with high-p_T hadron pairs

Author

Adolph, C., Alekseev, M. G., Alexakhin, V. Yu., Alexandrov, Yu., Alexeev, G. D., Amoroso, A., Antonov, A. A., Austregesilo, A., Badelek, B., Balestra, F., Barth, J., Baum, G., Bedfer, Y., Bernhard, J., Bertini, R., Bettinelli, M., Bicker, K., Bieling, J., Birsa, R., Bisplinghoff, J., Bordalo, P., Bradamante, F., Braun, C., Bravar, A., Bressan, A., Burtin, E., Chaberny, D., Chiosso, M., Chung, S. U., Cicuttin, A., Crespo, M. L., Torre, S. Dalla, Das, S., Dasgupta, S. S., Denisov, O. Yu., Dhara, L., Donskov, S. V., Doshita, N., Duic, V., Duennweber, W., Dziewiecki, M., Efremov, A., Elia, C., Eversheim, P. D., Eyrich, W., Faessler, M., Ferrero, A., Filin, A., Finger, M., Finger jr., M., Fischer, H., Franco, C., von Hohenesche, N. du Fresne, Friedrich, J. M., Garfagnini, R., Gautheron, F., Gavrichtchouk, O. P., Gazda, R., Gerassimov, S., Geyer, R., Giorgi, M., Gnesi, I., Gobbo, B., Goertz, S., Grabmueller, S., Grasso, A., Grube, B., Gushterski, R., Guskov, A., Guthoerl, T., Haas, F., von Harrach, D., Hedicke, S., Heinsius, F. H., Herrmann, F., Hess, C., Hinterberger, F., Horikawa, N., Hoeppner, Ch., d'Hose, N., Huber, S., Ishimoto, S., Ivanov, O., Ivanshin, Yu., Iwata, T., Jahn, R., Jasinski, P., Joosten, R., Kabuss, E., Kang, D., Ketzer, B., Khaustov, G. V., Khokhlov, Yu. A., Kisselev, Yu., Klein, F., Klimaszewski, K., Koblitz, S., Koivuniemi, J. H., Kolosov, V. N., Kondo, K., Koenigsmann, K., Konorov, I., Konstantinov, V. F., Korzenev, A., Kotzinian, A. M., Kouznetsov, O., Kraemer, M., Kroumchtein, Z. V., Kunne, F., Kurek, K., Lauser, L., Goff, J. -M. Le, Lednev, A. A., Lehmann, A., Levorato, S., Lichtenstadt, J., Maggiora, A., Magnon, A., Makke, N., Mallot, G. K., Mann, A., Marchand, C., Martin, A., Marzec, J., Matsuda, T., Meyer, W., Michigami, T., Mikhailov, Yu. V., Moinester, M. A., Morreale, A., Mutter, A., Nagaytsev, A., Nagel, T., Nassalski, J. P., Nerling, F., Neubert, S., Neyret, D., Nikolaenko, V. I., Nowak, W. D., Nunes, A. S., Olshevsky, A. G., Ostrick, M., Padee, A., Panknin, R., Panzieri, D., Parsamyan, B., Paul, S., Perevalova, E., Pesaro, G., Peshekhonov, D. V., Piragino, G., Platchkov, S., Pochodzalla, J., Polak, J., Polyakov, V. A., Pontecorvo, G., Procureur, S. L., Pretz, J., Quaresma, M., Quintans, C., Rajotte, J. -F., Ramos, S., Rapatsky, V., Reicherz, G., Richter, A., Rocco, E., Rondio, E., Rossiyskaya, N. S., Ryabchikov, D. I., Samoylenko, V. D., Sandacz, A., Sapozhnikov, M. G., Sarkar, S., Savin, I. A., Sbrizzai, G., Schiavon, P., Schill, C., Schlueter, T., Schmidt, K., Schmitt, L., Schoenning, K., Schopferer, S., Schott, M., Shevchenko, O. Yu., Silva, L., Sinha, L., Sissakian, A. N., Slunecka, M., Smirnov, G. I., Sosio, S., Sozzi, F., Srnka, A., Stolarski, M., Sulc, M., Sulej, R., Sznajder, P., Takekawa, S., Ter Wolbeek, J., Tessaro, S., Tessarotto, F., Tkatchev, L. G., Uhl, S., Uman, I., Vandenbroucke, M., Virius, M., Vlassov, N. V., Wang, L., Windmolders, R., Wislicki, W., Wollny, H., Zaremba, K., Zavertyaev, M., Zemlyanichkina, E., Ziembicki, M., Zhuravlev, N., and Zvyagin, A.

Subjects
High Energy Physics - Experiment
Abstract

We present a determination of the gluon polarisation Delta g/g in the nucleon, based on the longitudinal double-spin asymmetry of DIS events with a pair of large transverse-momentum hadrons in the final state. The data were obtained by the COMPASS experiment at CERN using a 160 GeV/c polarised muon beam scattering off a polarised ^6LiD target. The gluon polarisation is evaluated by a Neural Network approach for three intervals of the gluon momentum fraction x_g covering the range 0.04 < x_g < 0.27. The values obtained at leading order in QCD do not show any significant dependence on x_g. Their average is Delta g/g = 0.125 +/- 0.060 (stat.) +/- 0.063 (syst.) at x_g=0.09 and a scale of mu^2 = 3 (GeV/c)^2., Comment: 13 pages, 6 figures and 3 tables

Published
2012
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9. First Measurement of Chiral Dynamics in \pi^- \gamma -> \pi^- \pi^- \pi^+

Author

Alekseev, M. G., Alexakhin, V. Yu., Alexandrov, Yu., Alexeev, G. D., Amoroso, A., Austregesilo, A., Badelek, B., Balestra, F., Barth, J., Baum, G., Bedfer, Y., Bernhard, J., Bertini, R., Bettinelli, M., Bicker, K., Birsa, R., Bisplinghoff, J., Bordalo, P., Bradamante, F., Bravar, A., Bressan, A., Burtin, E., Chaberny, D., Chiosso, M., Chung, S. U., Cicuttin, A., Crespo, M. L., Torre, S. Dalla, Das, S., Dasgupta, S. S., Denisov, O. Yu., Dhara, L., Donskov, S. V., Doshita, N., Duic, V., Dünnweber, W., Dziewiecki, M., Efremov, A., Eversheim, P. D., Eyrich, W., Faessler, M., Ferrero, A., Filin, A., Finger, M., Finger Jr, M., Fischer, H., Franco, C., von Hohenesche, N. du Fresne, Friedrich, J. M., Garfagnini, R., Gautheron, F., Gavrichtchouk, O. P., Gazda, R., Gerassimov, S., Geyer, R., Giorgi, M., Gnesi, I., Gobbo, B., Goertz, S., uller, S. Grabm\", Grasso, A., Grube, B., Gushterski, R., Guskov, A., Haas, F., von Harrach, D., Hasegawa, T., Heinsius, F. H., Herrmann, F., Hess, C., Hinterberger, F., Horikawa, N., Höppner, Ch., d'Hose, N., Huber, S., Ishimoto, S., Ivanov, O., Ivanshin, Yu., Iwata, T., Jahn, R., Jasinski, P., Jegou, G., Joosten, R., Kabuss, E., Kang, D., Ketzer, B., Khaustov, G. V., Khokhlov, Yu. A., Kisselev, Yu., Klein, F., Klimaszewski, K., Koblitz, S., Koivuniemi, J. H., Kolosov, V. N., Kondo, K., Königsmann, K., Konorov, I., Konstantinov, V. F., Korzenev, A., Kotzinian, A. M., Kouznetsov, O., Krämer, M., Kroumchtein, Z. V., Kunne, F., Kurek, K., Lauser, L., Lednev, A. A., Lehmann, A., Levorato, S., Lichtenstadt, J., Maggiora, A., Magnon, A., Makke, N., Mallot, G. K., Mann, A., Marchand, C., Martin, A., Marzec, J., Massmann, F., Matsuda, T., Meyer, W., Michigami, T., Mikhailov, Yu. V., Moinester, M. A., Morreale, A., Mutter, A., Nagaytsev, A., Nagel, T., Nerling, F., Neubert, S., Neyret, D., Nikolaenko, V. I., Nowak, W. -D., Nunes, A. S., Olshevsky, A. G., Ostrick, M., Padee, A., Panknin, R., Panzieri, D., Parsamyan, B., Paul, S., Perevalova, E., Pesaro, G., Peshekhonov, D. V., Piragino, G., Platchkov, S., Pochodzalla, J., Polak, J., Polyakov, V. A., Pontecorvo, G., Pretz, J., Quintans, C., Rajotte, J. -F., Ramos, S., Rapatsky, V., Reicherz, G., Richter, A., Rocco, E., Rondio, E., Ryabchikov, D. I., Samoylenko, V. D., Sandacz, A., Santos, H., Sapozhnikov, M. G., Sarkar, S., Savin, I. A., Sbrizzai, G., Schiavon, P., Schill, C., Schlüter, T., Schmitt, L., Schopferer, S., Schröder, W., Shevchenko, O. Yu., Siebert, H. -W., Silva, L., Sinha, L., Sissakian, A. N., Slunecka, M., Smirnov, G. I., Sosio, S., Sozzi, F., Srnka, A., Stolarski, M., Sulc, M., Sulej, R., Sznajder, P., Takekawa, S., Tessaro, S., Tessarotto, F., Teufel, A., Tkatchev, L. G., Uhl, S., Uman, I., Vandenbroucke, M., Virius, M., Vlassov, N. V., Windmolders, R., Wiślicki, W., Wollny, H., Zaremba, K., Zavertyaev, M., Zemlyanichkina, E., Ziembicki, M., Zhuravlev, N., and Zvyagin, A.

Subjects
High Energy Physics - Experiment
Abstract

The COMPASS collaboration at CERN has investigated the \pi^- \gamma -> \pi^- \pi^- \pi^+ reaction at center-of-momentum energy below five pion masses, sqrt(s) < 5 m(\pi), embedded in the Primakoff reaction of 190 GeV pions impinging on a lead target. Exchange of quasi-real photons is selected by isolating the sharp Coulomb peak observed at smallest momentum transfers, t' < 0.001 (GeV/c)^2. Using partial-wave analysis techniques, the scattering intensity of Coulomb production described in terms of chiral dynamics and its dependence on the 3\pi-invariant mass m(3\pi) = sqrt(s) were extracted. The absolute cross section was determined in seven bins of $\sqrt{s}$ with an overall precision of 20%. At leading order, the result is found to be in good agreement with the prediction of chiral perturbation theory over the whole energy range investigated., Comment: 10 pages, 5 figures

Published
2011
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10. Measurements of Cross Sections and Charged Pion Spectra in Proton-Carbon Interactions at 31 GeV/c

Author

Abgrall, N., Aduszkiewicz, A., Andrieu, B., Anticic, T., Antoniou, N., Argyriades, J., Asryan, A. G., Baatar, B., Blondel, A., Blumer, J., Bogusz, M., Boldizsar, L., Bravar, A., Brooks, W., Brzychczyk, J., Bubak, A., Bunyatov, S. A., Busygina, O., Cetner, T., Choi, K. -U., Christakoglou, P., Chung, P., Czopowicz, T., Davis, N., Diakonos, F., Di Luise, S., Dominik, W., Dumarchez, J., Engel, R., Ereditato, A., Esposito, L. S., Feofilov, G. A., Fodor, Z., Ferrero, A., Fulop, A., Garrido, X., Gazdzicki, M., Golubeva, M., Grebieszkow, K., Grzeszczuk, A., Guber, F., Hakobyan, H., Hasegawa, T., Igolkin, S., Ivanov, A. S., Ivanov, Y., Ivashkin, A., Kadija, K., Kapoyannis, A., Katrynska, N., Kielczewska, D., Kikola, D., Kim, J. -H., Kirejczyk, M., Kisiel, J., Kobayashi, T., Kochebina, O., Kolesnikov, V. I., Kolev, D., Kondratiev, V. P., Korzenev, A., Kowalski, S., Kuleshov, S., Kurepin, A., Lacey, R., Lagoda, J., Laszlo, A., Lyubushkin, V. V., Mackowiak, M., Majka, Z., Malakhov, A. I., Marchionni, A., Marcinek, A., Maris, I., Marin, V., Matulewicz, T., Matveev, V., Melkumov, G. L., Meregaglia, A., Messina, M., Mrowczynski, St., Murphy, S., Nakadaira, T., Naumenko, P. A., Nishikawa, K., Palczewski, T., Palla, G., Panagiotou, A. D., Peryt, W., Petukhov, O., Planeta, R., Pluta, J., Popov, B. A., Posiadala, M., Pulawski, S., Rauch, W., Ravonel, M., Renfordt, R., Robert, A., Rohrich, D., Rondio, E., Rossi, B., Roth, M., Rubbia, A., Rybczynski, M., Sadovsky, A., Sakashita, K., Sekiguchi, T., Seyboth, P., Shibata, M., Sissakian, A. N., Skrzypczak, E., Slodkowski, M., Sorin, A. S., Staszel, P., Stefanek, G., Stepaniak, J., Strabel, C., Strobele, H., Susa, T., Szaflik, P., Szuba, M., Tada, M., Taranenko, A., Tsenov, R., Ulrich, R., Unger, M., Vassiliou, M., Vechernin, V. V., Vesztergombi, G., Wilczek, A., Wlodarczyk, Z., Wojtaszek, A., Yi, J. -G., Yoo, I. -K., and Zipper, W.

Subjects
High Energy Physics - Experiment
Abstract

Interaction cross sections and charged pion spectra in p+C interactions at 31 GeV/c were measured with the large acceptance NA61/SHINE spectrometer at the CERN SPS. These data are required to improve predictions of the neutrino flux for the T2K long baseline neutrino oscillation experiment in Japan. A set of data collected during the first NA61/SHINE run in 2007 with an isotropic graphite target with a thickness of 4% of a nuclear interaction length was used for the analysis. The measured p+C inelastic and production cross sections are 257.2 +- 1.9 +- 8.9 mb and 229.3 +- 1.9 +- 9.0 mb, respectively. Inclusive production cross sections for negatively and positively charged pions are presented as a function of laboratory momentum in 10 intervals of the laboratory polar angle covering the range from 0 up to 420 mrad. The spectra are compared with predictions of several hadron production models., Comment: updated version; as published by Phys. Rev. C

Published
2011
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11. Duality of thermal and dynamical descriptions in particle interactions

Author

Cleymans, J., Lykasov, G. I., Sissakian, A. N., Sorin, A. S., and Teryaev, O. V.

Subjects
High Energy Physics - Phenomenology
Abstract

We suggest a duality between the statistical and standard (dynamical) distributions of partons in the nucleons. The temperature parameter entering into the statistical form for the quark distributions is estimated. It is found that this effective temperature is practically the same for the dependence on logitudinal and transverse momenta and, it is close to the freeze-out temperature in high energy heavy-ion collisions., Comment: 8 pages, 1 figure

Published
2010

12. Thermal Effects for Quark and Gluon Distributions in Heavy-Ion Collisions

Author

Lykasov, G. I., Sissakian, A. N., Sorin, A. S., and Teryaev, O. V.

Subjects
Nuclear Theory
Abstract

In-medium effects for distributions of quarks and gluons in central A+A collisions are considered. We suggest a duality principle, which means similarity of thermal spectra of hadrons produced in heavy-ion collisions and inclusive spectra which can be obtained within the dynamic quantum scattering theory. Within the suggested approach we show that the mean square of the transverse momentum for these partons grows and then saturates when the initial energy increases. It leads to the energy dependence of hadron transverse mass spectra which is similar to that observed in heavy ion collisions., Comment: 6 pages, LaTeX, 2 figures. Contribution to the XIII International Conference "Selected Problems of Modern Theoretical Physics", JINR, Dubna, June 23 - 27, 2008

Published
2009

13. Resonance Structure in the $\gamma\gamma$ Invariant Mass Spectrum in $p$C- and $d$C-Interactions

Author

Abraamyan, Kh. U., Baznat, M. I., Friesen, A. V., Gudima, K. K., Kozhin, M. A., Lebedev, S. A., Nazarenko, M. A., Nikitin, S. A., Ososkov, G. A., Reznikov, S. G., Sissakian, A. N., Sorin, A. S., and Toneev, V. D.

Subjects
Nuclear Experiment
Abstract

Along with $\pi^0$ and $\eta$ mesons, a resonance structure in the invariant mass spectrum of two photons at $M_{\gamma\gamma}= 360 \pm 7 \pm 9$ MeV is observed in the reaction $d C\to\gamma + \gamma +X$ at momentum 2.75 GeV/c per nucleon. Estimates of its width and production cross section are $\Gamma = 63.7 \pm 17.8$ MeV and $\sigma_{\gamma\gamma}=98\pm24^{+93}_{-67} {\rm \mu b}$, respectively. The collected statistics amount to $2339 \pm 340$ events of $1.5\cdot 10^6$ triggered interactions of a total number $\sim 10^{12}$ of $d$C-interactions. This resonance structure is not observed in $p$C collisions at the beam momentum 5.5 GeV/c. Possible mechanisms of this ABC-like effect are discussed.

Published
2008
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14. Transverse momentum spectra of hadrons produced in central heavy-ion collisions

Author

Lykasov, G. I., Sissakian, A. N., Sorin, A. S., and Toneev, V. D.

Subjects
Nuclear Theory
Abstract

In-medium effects of transverse-mass distributions of quarks and gluons are considered assuming a possible local equilibrium for colorless quark objects like mesons and baryons created in central A+A collisions. It is shown that the average square of the transverse momentum for these partons grows and then saturates when the initial energy increases. Within the quark-gluon string model it leads to the energy dependence of hadron transverse mass spectra which is similar to that observed in heavy ion collisions. Comparison with other scenarios is given., Comment: 16 pages, 3 figures. Talk given at the Workshop "Relativistic Nuclear Physics: from Nuclotron to LHC energies", Kiev, Ukraine, June 18-22, 2007

Published
2008
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15. Collins and Sivers asymmetries for pions and kaons in muon-deuteron DIS

Author

The COMPASS Collaboration, Alekseev, M., Alexakhin, V. Yu., Alexandrov, Yu., Alexeev, G. D., Amoroso, A., Arbuzov, A., Badełek, B., Balestra, F., Ball, J., Barth, J., Baum, G., Bedfer, Y., Bernet, C., Bertini, R., Bettinelli, M., Birsa, R., Bisplinghoff, J., Bordalo, P., Bradamante, F., Bravar, A., Bressan, A., Brona, G., Burtin, E., Bussa, M. P., Chapiro, A., Chiosso, M., Cicuttin, A., Colantoni, M., Costa, S., Crespo, M. L., Torre, S. Dalla, Dafni, T., Das, S., Dasgupta, S. S., De Masi, R., Dedek, N., Denisov, O. Yu., Dhara, L., Diaz, V., Dinkelbach, A. M., Donskov, S. V., Dorofeev, V. A., Doshita, N., Duic, V., Dünnweber, W., Eversheim, P. D., Efremov, A. V., Eyrich, W., Faessler, M., Falaleev, V., Ferrero, A., Ferrero, L., Finger, M., Finger Jr., M., Fischer, H., Franco, C., Franz, J., Friedrich, J. M., Frolov, V., Garfagnini, R., Gautheron, F., Gavrichtchouk, O. P., Gazda, R., Gerassimov, S., Geyer, R., Giorgi, M., Gobbo, B., Goertz, S., Gorin, A. M., Grabmüller, S., Grajek, O. A., Grasso, A., Grube, B., Gushterski, R., Guskov, A., Haas, F., Hannappel, J., von Harrach, D., Hasegawa, T., Heckmann, J., Hedicke, S., Heinsius, F. H., Hermann, R., Heß, C., Hinterberger, F., von Hodenberg, M., Horikawa, N., Horikawa, S., d'Hose, N., Ilgner, C., Ioukaev, A. I., Ishimoto, S., Ivanov, O., Ivanshin, Yu., Iwata, T., Jahn, R., Janata, A., Jasinski, P., Joosten, R., Jouravlev, N. I., Kabuß, E., Kang, D., Ketzer, B., Khaustov, G. V., Khokhlov, Yu. A., Kisselev, Yu., Klein, F., Klimaszewski, K., Koblitz, S., Koivuniemi, J. H., Kolosov, V. N., Komissarov, E. V., Kondo, K., Königsmann, K., Konorov, I., Konstantinov, V. F., Korentchenko, A. S., Korzenev, A., Kotzinian, A. M., Koutchinski, N. A., Kouznetsov, O., Kral, A., Kravchuk, N. P., Kroumchtein, Z. V., Kuhn, R., Kunne, F., Kurek, K., Ladygin, M. E., Lamanna, M., Goff, J. M. Le, Lednev, A. A., Lehmann, A., Levorato, S., Lichtenstadt, J., Liska, T., Ludwig, I., Maggiora, A., Maggiora, M., Magnon, A., Mallot, G. K., Mann, A., Marchand, C., Marroncle, J., Martin, A., Marzec, J., Massmann, F., Matsuda, T., Maximov, A. N., Meyer, W., Mielech, A., Mikhailov, Yu. V., Moinester, M. A., Mutter, A., Nagaytsev, A., Nagel, T., Nähle, O., Nassalski, J., Neliba, S., Nerling, F., Neubert, S., Neyret, D. P., Nikolaenko, V. I., Nikolaev, K., Olshevsky, A. G., Ostrick, M., Padee, A., Pagano, P., Panebianco, S., Panknin, R., Panzieri, D., Paul, S., Pawlukiewicz-Kaminska, B., Peshekhonov, D. V., Peshekhonov, V. D., Piragino, G., Platchkov, S., Pochodzalla, J., Polak, J., Polyakov, V. A., Pretz, J., Procureur, S., Quintans, C., Rajotte, J. -F., Ramos, S., Rapatsky, V., Reicherz, G., Reggiani, D., Richter, A., Robinet, F., Rocco, E., Rondio, E., Rozhdestvensky, A. M., Ryabchikov, D. I., Samoylenko, V. D., Sandacz, A., Santos, H., Sapozhnikov, M. G., Sarkar, S., Savin, I. A., Schiavon, P., Schill, C., Schmitt, L., Schönmeier, P., Schröder, W., Shevchenko, O. Yu., Siebert, H. -W., Silva, L., Sinha, L., Sissakian, A. N., Slunecka, M., Smirnov, G. I., Sosio, S., Sozzi, F., Srnka, A., Stinzing, F., Stolarski, M., Sugonyaev, V. P., Sulc, M., Sulej, R., Tchalishev, V. V., Tessaro, S., Tessarotto, F., Teufel, A., Tkatchev, L. G., Venugopal, G., Virius, M., Vlassov, N. V., Vossen, A., Webb, R., Weise, E., Weitzel, Q., Windmolders, R., Wirth, S., Wiślicki, W., Wollny, H., Zaremba, K., Zavertyaev, M., Zemlyanichkina, E., Zhao, J., Ziegler, R., and Zvyagin, A.

Subjects
High Energy Physics - Experiment
Abstract

The measurements of the Collins and Sivers asymmetries of identified hadrons produced in deep-inelastic scattering of 160 GeV/c muons on a transversely polarised 6LiD target at COMPASS are presented. The results for charged pions and charged and neutral kaons correspond to all data available, which were collected from 2002 to 2004. For all final state particles both the Collins and Sivers asymmetries turn out to be small, compatible with zero within the statistical errors, in line with the previously published results for not identified charged hadrons, and with the expected cancellation between the u- and d-quark contributions., Comment: 16 pages, 9 figures, added author Efremov, calculated pure kaon asymmetries instead of those for experimental kaon/pion mixture (mainly error affected)

Published
2008
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16. Collective effects in central heavy-ion collisions

Author

Lykasov, G. I., Sissakian, A. N., Sorin, A. S., and Toneev, V. D.

Subjects
Nuclear Theory
Abstract

In-medium effects on transverse-mass distributions of quarks and gluons are considered assuming a possible local equilibrium for colorless quark objects (mesons and baryons) created in central A-A collisions. It is shown that the average transverse momentum squared for these partons grows and then saturates when the initial energy increases. Within the quark-gluon string model it leads to the colliding energy dependence of hadron transverse mass spectra which is similar to that observed in heavy ion collisions. Comparison with other scenarios is given., Comment: 5 pages, 2 figures. Talk given at 13th Lomonosov Conference on Elementary Particle Physics, Moscow, Russia, August 23-29, 2007

Published
2008
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17. The electromagnetic effects in $K_{e4}$ decay

Author

Gevorkyan, S. R., Sissakian, A. N., Tarasov, A. V., Torosyan, H. T., and Voskresenskaya, O. O.

Subjects
High Energy Physics - Phenomenology
Abstract

The final state interaction of pions in $K_{e4}$ decay allows one to obtain the value of the isospin and angular momentum zero $\pi\pi$ scattering length $a_0^0$.We take into account the electromagnetic interaction of pions and isospin symmetry breaking effects caused by different masses of neutral and charged pions and estimate the impact of these effects on the procedure of scattering length extraction from $K_{e4}$ decay., Comment: 8 pages,1 figure

Published
2007
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18. The isospin symmetry breaking effects in $K_{e4}$ decays

Author

Gevorkyan, S. R., Sissakian, A. N., Tarasov, A. V., Torosyan, H. T., and Voskresenskaya, O. O.

Subjects
High Energy Physics - Phenomenology
Abstract

The Fermi-Watson theorem is generalized to the case of two coupled channels with different masses and applied to final state interaction in $K_{e4}$ decays. The impact of considered effect on the phase of the $\pi\pi$ scattering is estimated and shown that it can be crucial for scattering lengths extraction from experimental data on $K_{e4}$ decays.

Published
2007
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19. Properties of lightest mesons at finite temperature and quark/baryon chemical potential in instanton model of QCD vacuum

Author

Molodtsov, S. V., Sissakian, A. N., Sorin, A. S., and Zinovjev, G. M.

Subjects
High Energy Physics - Phenomenology
Abstract

The thermal and quark/baryon chemical potential dependences of quark condensate and masses of $\pi$- and $\sigma$-mesons are studied in the instanton model of the QCD vacuum in precritical region. The impact of phonon-like excitations of instanton liquid on the characteristics of $\sigma$-meson in such an environment is also examined., Comment: 9 pages, 3 figures

Published
2007
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20. Towards light scalar meson structure in terms of quark and gluon degrees of freedom

Author

Molodtsov, S. V., Siemiarczuk, T., Sissakian, A. N., Sorin, A. S., and Zinovjev, G. M.

Subjects
High Energy Physics - Phenomenology
Abstract

The origin of the lightest scalar mesons is studied in the framework of instanton liquid model (ILM) of the QCD vacuum. The impact of vacuum excitations on the sigma-meson features is analyzed in detail. In particular, it is noticed that the changes produced in the scalar sector may unexpectedly become quite considerable in spite of insignificant values of corrections to the dynamical quark masses and then the medley of sigma-meson and those excitations may reveal itself as broad resonance states of vitally different masses., Comment: 10 pages, 1 figure, LaTeX

Published
2006

21. QCD Matter: A Search for a Mixed Quark-Hadron Phase

Author

Sissakian, A. N., Sorin, A. S., and Toneev, V. D.

Subjects
Nuclear Theory, High Energy Physics - Phenomenology, Nuclear Experiment
Abstract

Physics aspects of a JINR project to reach the planned 5A GeV energy for the Au and U beams and to increase the bombarding energy up to 10A GeV are discussed. The project aims to search for a possible formation of a strongly interacting mixed quark-hadron phase. The relevant problems are exemplified. A need for scanning heavy-ion interactions in bombarding energy, collision centrality and isospin asymmetry is emphasized., Comment: 23 pages, 16 figures, LaTeX, talk given at XXXIII International Conference On High Energy Physics (ICHEP'06), Moscow, 26.07- 02.08, 2006

Published
2006

22. Path Integral Approach for Superintegrable Potentials on Spaces of Non-constant Curvature: I. Darboux Spaces DI and DII

Author

Grosche, Christian, Pogosyan, George S., and Sissakian, Alexei N.

Subjects
Quantum Physics
Abstract

In this paper the Feynman path integral technique is applied for superintegrable potentials on two-dimensional spaces of non-constant curvature: these spaces are Darboux spaces D_I and D_II, respectively. On D_I there are three and on D_II four such potentials, respectively. We are able to evaluate the path integral in most of the separating coordinate systems, leading to expressions for the Green functions, the discrete and continuous wave-functions, and the discrete energy-spectra. In some cases, however, the discrete spectrum cannot be stated explicitly, because it is either determined by a transcendental equation involving parabolic cylinder functions (Darboux space I), or by a higher order polynomial equation. The solutions on D_I in particular show that superintegrable systems are not necessarily degenerate. We can also show how the limiting cases of flat space (constant curvature zero) and the two-dimensional hyperboloid (constant negative curvature) emerge.

Published
2006
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23. Observation of New Resonance Structure in the Invariant Mass Spectrum of Two gamma-Quanta in dC-Interactions at Momentum 2.75 GeV/c per Nucleon

Author

Abraamyan, Kh. U., Sissakian, A. N., and Sorin, A. S.

Subjects
Nuclear Experiment, High Energy Physics - Phenomenology, Nuclear Theory
Abstract

A new resonance structure at M = 355 \pm 6 \pm 9 MeV is observed in the invariant mass spectrum of two gamma-quanta produced in the reaction d + C => gamma + gamma + x at momentum 2.75 GeV/c per nucleon. Preliminary estimates of its width and cross section are Gamma = 41 \pm 12 MeV and sigma_{gamma-gamma} = 0.6 mkb. The collected statistics is 2680 \pm 310 events of 1.5 10^6 triggered interactions of a total number 3 10^{12} dC-interactions., Comment: 10 pages, 10 figures, LaTeX

Published
2006

24. NLO QCD method of the polarized SIDIS data analysis

Author

Sissakian, A. N., Shevchenko, O. Yu., and Ivanov, O. N.

Subjects
High Energy Physics - Phenomenology
Abstract

Method of polarized semi-inclusive deep inelastic scattering (SIDIS) data analysis in the next to leading order (NLO) QCD is developed. Within the method one first directly extracts in NLO few first truncated (available to measurement) Mellin moments of the quark helicity distributions. Second, using these moments as an input to the proposed modification of the Jacobi polynomial expansion method (MJEM), one eventually reconstructs the local quark helicity distributions themselves. All numerical tests demonstrate that MJEM allows us to reproduce with the high precision the input local distributions even inside the narrow Bjorken $x$ region accessible for experiment. It is of importance that only four first input moments are sufficient to achieve a good quality of reconstruction. The application of the method to the simulated SIDIS data on the pion production is considered. The obtained results encourage one that the proposed NLO method can be successfully applied to the SIDIS data analysis. The analysis of HERMES data on pion production is performed. To this end the pion difference asymmetries are constructed from the measured by HERMES standard semi-inclusive spin asymmetries. The LO results of the valence distribution reconstruction are in a good accordance with the respective leading order SMC and HERMES results, while the NLO results are in agreement with the existing NLO parametrizations on these quantities.

Published
2006
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25. Towards Searching for a Mixed Phase of Strongly Interacting QCD Matter at the JINR Nuclotron

Author

Sissakian, A. N., Sorin, A. S., Suleymanov, M. K., Toneev, V. D., and Zinovjev, G. M.

Subjects
Nuclear Experiment, High Energy Physics - Phenomenology, Nuclear Theory
Abstract

Available experimental data in respect to a possible formation of a strongly interacting mixed phase are outlined. A physical program is formulated for new facilities being opend in Dubna for acceleration of heavy ions with an energy up to 5 AGeV., Comment: 26 pages, LaTeX

Published
2006

26. Search for a mixed phase of strongly interacting matter at the JINR Nuclotron

Author

Sissakian, A. N., Sorin, A. S., Suleymanov, M. K., Toneev, V. D., and Zinovjev, G. M.

Subjects
Nuclear Experiment, High Energy Physics - Experiment, High Energy Physics - Phenomenology, Nuclear Theory
Abstract

A physical program is formulated for new facilities opening in Dubna for acceleration of heavy ions with an energy up to 5 AGeV., Comment: 10 pages, 8 figures, LaTeX, Contribution to the Proceedings of the 8th International Workshop "Relativistic Nuclear Physics: from hundreds MeV to TeV", JINR, Dubna, May 23 - 28, 2005

Published
2005

27. Bose-Einstein correlations at LEP and Tevatron energies

Author

Kozlov, G. A., Lovas, L., Tokar, S., Boudagov, Yu. A., and Sissakian, A. N.

Subjects
High Energy Physics - Phenomenology
Abstract

Using the Bose-Einstein correlations (BEC) implemented in PYTHIA we investigated a possibility of the CDF experiment at the Tevatron to see the two-particle correlations in the final state of interactions. The approach based on quantum field theory at finite temperature was applied to the ALEPH data at LEP, and the BEC important parameters were retrieved., Comment: 5 pages, 4 figures, 1 table. Based on the talk gived at The 6th international workshop on very high multiplicity physics, JINR Dubna, 16-17 april 2005. In Table 1. the sign of error added

Published
2005

28. Direct extraction of transversity and its accompanying T-odd distribution from the unpolarized and single-polarized Drell-Yan processes

Author

Sissakian, A. N., Shevchenko, O. Yu., Nagaytsev, A. P., and Ivanov, O. N.

Subjects
High Energy Physics - Phenomenology
Abstract

The Drell-Yan (DY) processes with unpolarized colliding hadrons and with the single transversally polarized hadron are considered. The possibility of direct (without any model assumptions) extraction of both transversity and its accompanying T-odd parton distribution functions (PDF) is discussed. For DY processes measurements planned at GSI the preliminary estimations demonstrate that it is quite real to extract both transversity and its accompanying T-odd PDF in the PAX conditions.

Published
2005
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29. An approach to NLO QCD analysis of the semi-inclusive DIS data with modified Jacobi polynomial expansion method

Author

Sissakian, A. N., Shevchenko, O. Yu., and Ivanov, O. N.

Subjects
High Energy Physics - Phenomenology
Abstract

It is proposed the modification of the Jacobi polynomial expansion method (MJEM) which is based on the application of the truncated moments instead of the full ones. This allows to reconstruct with a high precision the local quark helicity distributions even for the narrow accessible for measurement Bjorken $x$ region using as an input only four first moments extracted from the data in NLO QCD. It is also proposed the variational (extrapolation) procedure allowing to reconstruct the distributions outside the accessible Bjorken $x$ region using the distributions obtained with MJEM in the accessible region. The numerical calculations encourage one that the proposed variational (extrapolation) procedure could be applied to estimate the full first (especially important) quark moments.

Published
2005
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30. The amplitude of lepton-pair production in relativistic ion collisions beyond the perturbative theory

Author

Sissakian, A. N., Tarasov, A. V., Torosyan, H. T., and Voskresenskaya, O. O.

Subjects
High Energy Physics - Phenomenology
Abstract

We investigate the structure of some first terms of Watson series representing the amplitude of lepton-pair production in the ion collisions. It is shown that infrared instabilities of individual terms trend to cancel each other providing the infrared stability of whole amplitude., Comment: LaTex, 6 pages, no figures

Published
2005

31. $e^+e^-$ pair production in relativistic ions collision and its correspondence to electron-ion scattering

Author

Sissakian, A. N., Tarasov, A. V., Torosyan, H. T., and Voskresenskaya, O. O.

Subjects
High Energy Physics - Phenomenology
Abstract

It is shown that the amplitudes of electron-ion scattering and $e^+e^-$ pair production in the Coulomb field of two colliding ions are sxpressed in the terms of electron scattering amplitudes in the fields of the individual ions via the Watson expansion. We have obtained the compact expressions for these amplitudes valid in the high energy limit and discuss the crossing symmetry relations among the considered processes., Comment: 5 pages, no figures, LaTEX; submitted to Physics Letters B

Published
2004

32. NLO QCD procedure of the semi-inclusive deep inelastic scattering data analysis with respect to the light quark polarized sea

Author

Sissakian, A. N., Shevchenko, O. Yu., and Ivanov, O. N.

Subjects
High Energy Physics - Phenomenology
Abstract

The semi-inclusive deep inelastic scattering (SIDIS) process is considered. A theoretical procedure is proposed allowing the direct extraction from the SIDIS data of the first moments of the polarized valence distributions and of the first moment difference of the light sea quark polarized distributions in the next to leading QCD order. The validity of the procedure is confirmed by the respective simulations.

Published
2004
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33. The $e^+e^-$ pair production in relativistic ions collision and its correspondence to electron scattering

Author

Sissakian, A. N., Tarasov, A. V., Torosyan, H. T., and Voskresenskaya, O. O.

Subjects
Nuclear Theory
Abstract

It is shown that the processes of electron(positron) scattering and $e^+e^-$ pair production in the Coulomb fields of two relativistic ions, can be expressed through the amplitudes of lepton scattering off the ion Coulomb field via Watson expansion. We obtained the compact expressions for these amplitudes valid in the high energy limit and discuss the crossing symmetry relations among the considered processes., Comment: 5 pages

Published
2004

34. Possibility of a dynamical Higgs mechanism and of the respective phase transition induced by a boundary

Author

Sissakian, A. N., Shevchenko, O. Yu., and Samoilov, V. N.

Subjects
High Energy Physics - Theory
Abstract

The dynamical quantum effects arising due to the boundary presence with two types of boundary conditions (BC) satisfied by scalar fields are studied. It is shown that while the Neumann BC lead to the usual scalar field mass generation, the Dirichlet BC give rise to the dynamical mechanism of spontaneous symmetry breaking. Due to the later, there arises the possibility of the respective phase transition from the normal phase to the spontaneously broken one. In particular, at the critical value of the combined evolution parameter the usual massless scalar QED transforms to the Higgs model.

Published
2004
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35. NLO QCD procedure of the SIDIS data analysis with respect to light quark polarized sea

Author

Sissakian, A. N., Shevchenko, O. Yu., and Ivanov, O. N.

Subjects
High Energy Physics - Phenomenology
Abstract

The semi-inclusive deep inelastic scattering (SIDIS) process is considered. It is proposed a theoretical procedure allowing the direct extraction from the SIDIS data of the first moments of the polarized valence distributions and of the first moment difference of the light sea quark polarized distributions in the next to leading (NLO) QCD order. The validity of the procedure is confirmed by the respective simulations.

Published
2003

36. Possibility of the new type phase transition

Author

Sissakian, A. N., Shevchenko, O. Yu., and Samoilov, V. N.

Subjects
High Energy Physics - Theory
Abstract

The scalar field theory and the scalar electrodynamics quantized in the flat gap are considered. The dynamical effects arising due to the boundary presence with two types of boundary conditions (BC) satisfied by scalar fields are studied. It is shown that while the Neumann BC lead to the usual scalar field mass generation, the Dirichlet BC give rise to the dynamical mechanism of spontaneous symmetry breaking. Due to the later, there arises the possibility of the new type phase transition from the normal to spontaneously broken phase. The decreasing in the characteristic size of the quantization region (the gap size here) and increasing in the temperature compete with each other, tending to transport the system in the spontaneously broken and in the normal phase, respectively. The system evolves with a combined parameter, simultaneously reflecting the change in temperature and in the size. As a result, at the critical value of this parameter there occurs the phase transition from the normal phase to the spontaneously broken one. In particular, the usual massless scalar electrodynamics transforms to the Higgs model.

Published
2003

37. Comment on polarized quark distributions extracted from SIDIS experiments

Author

Sissakian, A. N., Shevchenko, O. Yu., and Ivanov, O. N.

Subjects
High Energy Physics - Phenomenology
Abstract

The results of SIDIS experiments concerning the first moments of the polarized quark distributions are considered. The possible reasons of the deviation from the fundamental restrictions such as the Bjorken sum rule and the ways to properly improve the analysis of measured SIDIS asymmetries are discussed. The possibility of broken polarized sea scenario is analysed.

Published
2003
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38. Production of (super)heavy quarkonia and new Higgs physics at hadron colliders

Author

Kozlov, G. A., Sissakian, A. N., Khubua, J. I., Arabidze, G., Khoriauli, G., and Morii, T.

Subjects
High Energy Physics - Phenomenology
Abstract

Based on the two Higgs doublet model, we study the effect of Higgs-boson exchange on the (super)heavy quarkonium \bar QQ, which induces a strong attractive force between a (super)heavy quark Q and an antiquark \bar Q. An interesting application is the decay of (super)heavy quarkonia \bar QQ into a Higgs boson associated with gauge bosons. The criterion for making the \bar QQ bound state is studied. We also show that non-perturbative effects due to gluonic field fluctuations are rather small in such a heavy quark sector. Possible enhancement for productions and decays of \bar QQ bound states made from the fourth generation quark Q is discussed for \bar p p (at the Tevatron) and pp (at the LHC) collisions., Comment: 18 pages, REVTeX, 9 figures. V2: minor changes, references and acknowledgments added

Published
2003
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39. Two exactly-solvable problems in one-dimensional quantum mechanics on circle

Author

Mardoyan, L. G., Pogosyan, G. S., and Sissakian, A. N.

Subjects
Quantum Physics, High Energy Physics - Theory, Mathematical Physics
Abstract

In this note we establish a relation between two exactly-solvable problems on circle, namely singular Coulomb and singular oscillator systems., Comment: 6 pages, submitted in the Proceedings of the Workshop on "Superintegrability in Classical an Quantum Systems" (September 16-22, 2002, Montreal)

Published
2003

40. Topological charge and topological susceptibility in connection with translation and gauge invariance

Author

Kotzinian, A. M., Shevchenko, O. Yu., and Sissakian, A. N.

Subjects
High Energy Physics - Theory
Abstract

It is shown that the evaluation of the expectation value (EV) of topological charge density over $\theta$-vacuum is reduced to investigation of the Chern-Simons term EV. An equation for this quantity is established and solved. EV of the topological charge density at an arbitrary $\theta$ occurs equal to zero and, as a consequence, topological susceptibility of both QCD and pure Yang-Mills vacua defined in a Wick sense is equal to zero, whereas when defined in a Dyson sense it differs from zero by the quantity proportional to the respective condensate of the chromomagnetic field. Thus, the usual Witten-Veneziano formula for the $\eta^{'}$ meson mass is modified.

Published
2002

41. Semi-inclusive polarized DIS in terms of Melin moments.I. Light sea quark polarized distribustions

Author

Sissakian, A. N., Shevchenko, O. Yu., and Samoilov, V. N.

Subjects
High Energy Physics - Phenomenology
Abstract

In connection with the semi-inclusive polarized DIS, it is proposed to consider the first Melin moments $\Delta q$ of the polarized quark and antiquark densities, instead of the respective variables $\delta q(x)$, local in Bjorken x themselves. This gives rise to a very essential simplification of the next to leading order (NLO) QCD and, besides, allows one to use the respective QCD sum rules. An expression for $\Delta\bar{u}-\Delta\bar{d}$ in NLO is obtained which is just a simple combination of the directly measured asymmetries and of the quantities taken from the unpolarized data., Comment: LaTeX, 9 pages, This paper was delivered on October 10 at Physics Workshop "Compass week in Dubna" (JINR, Dubna, 2000)

Published
2000

42. Topological Effects in Medium

Author

Sissakian, A. N., Shevchenko, O. Yu., and Solganik, S. B.

Subjects
High Energy Physics - Theory
Abstract

Two closely related topological phenomena are studied at finite density and temperature. These are chiral anomaly and Chern--Simons term. It occurs that the chiral anomaly doesn't depend on density and temperature. Chern-Simons term appearance in even dimensions is studied under two types of constraints: chiral and usual charges conservation. In odd dimensions, by using different methods it is shown that $\mu^2 = m^2$ is the crucial point for Chern--Simons at zero temperature. So when $\mu^2 < m^2$ $\mu$--influence disappears and we get the usual Chern-Simons term. On the other hand, when $\mu^2 > m^2$ the Chern-Simons term vanishes because of non--zero density of background fermions. The connection between parity anomalous Chern-Simons in odd dimension and chiral anomaly in even dimension is established at arbitrary density and temperature. These results hold in any dimension as in abelian, so as in nonabelian cases., Comment: to be published in Phys. of Elem. Part. and Atom. Nucl., 40 pages

Published
1998

43. On a Generalized D-Dimensional Oscillator: Interbasis Expansions

Author

Hakobyan, Ye. M., Pogosyan, G. S., and Sissakian, A. N.

Subjects
Quantum Physics, High Energy Physics - Theory, Mathematical Physics
Abstract

This article deals with nonrelativistic study of a D-dimensional superintegrable system, which generalizes the ordinary isotropic oscillator system. The coefficients for the expansion between the hyperspherical and Cartesian bases (transition matrix), and vice-versa, are found in terms of the SU(2) Clebsch--Gordan coefficients analytically continued to real values of their arguments. The diagram method, which allow one to construct a transition matrix for arbitrary dimension, is developed., Comment: 12 pages, LaTex

Published
1998

44. Hidden Symmetry of the Yang--Coulomb System

Author

Mardoyan, L. G., Sissakian, A. N., and Ter--Antonyan, V. M.

Subjects
High Energy Physics - Theory
Abstract

The bound system composed of the Yang monopole coupled to a particle of the isospin by the SU(2) and Coulomb interaction is considered. The generalized Runge--Lenz vector and the SO(6) group of hidden symmetry are established. It is also shown that the group of hidden symmetry make it possible to calculate the spectrum of the system by a pure algebraic method., Comment: 6 pages, LaTeX file

Published
1998
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45. SU(2) -- Monopole: Interbasis Expansion

Author

Mardoyan, L. G. and Sissakian, A. N.

Subjects
High Energy Physics - Theory
Abstract

This article deals with a nonrelativistic quantum mechanical study of a charge-dyon system with the SU(2)--monopole in five dimensions. The Schr\"odinger equation for this system is separable in the hyperspherical and parabolic coordinates. The problem of interbasis expansion of the wave functions is completely solved. The coefficients for the expansion of the parabolic basis in terms of the hyperspherical basis can be expressed through the Clebsch-Gordan coefficients of the group SU(2)., Comment: 9 pages, LaTeX file

Published
1998

46. 8D oscillator as a hidden SU(2) - monopole

Author

Mardoyan, L. G., Sissakian, A. N., and Ter-Antonyan, V. M.

Subjects
High Energy Physics - Theory
Abstract

In this report, in the framework of an analytical approach and with help of the generalized version of the Hurwitz transformation the five-dimensional SU(2)--monopole model is constructed from the eight-dimensional quantum oscillator. The SU(2)--monopole fields, the Clebsh-Gordan expansion stimulated by the space-gauge coupling, the hyperangle and the radial parts of the total wave function, the energy spectrum of the charge-monopole bound system and the corresponding degeneracy are calculated., Comment: 12 pages, LaTeX file

Published
1997

47. On a Generalized Oscillator: Invariance Algebra and Interbasis Expansions

Author

Hakobyan, Y. M., Kibler, M., Pogosyan, G. S., and Sissakian, A. N.

Subjects
Quantum Physics, Mathematical Physics, Physics - Atomic and Molecular Clusters, Physics - Atomic Physics, Physics - Chemical Physics
Abstract

This article deals with a quantum-mechanical system which generalizes the ordinary isotropic harmonic oscillator system. We give the coefficients connecting the polar and Cartesian bases for D=2 and the coefficients connecting the Cartesian and cylindrical bases as well as the cylindrical and spherical bases for D=3. These interbasis expansion coefficients are found to be analytic continuations to real values of their arguments of the Clebsch-Gordan coefficients for the group SU(2). For D=2, the superintegrable character for the generalized oscillator system is investigated from the points of view of a quadratic invariance algebra., Comment: 13 pages, Latex file. Submitted for publication to Yadernaya Fizika

Published
1997

48. Isotropic oscillator in the space of constant positive curvature. Interbasis expansions

Author

Hakobyan, Ye. M., Pogosyan, G. S., Sissakian, A. N., and Vinitsky, S. I.

Subjects
Quantum Physics, High Energy Physics - Theory, Mathematical Physics
Abstract

The Schr\"odinger equation is thoroughly analysed for the isotropic oscillator in the three-dimensional space of constant positive curvature in the spherical and cylindrical systems of coordinates. The expansion coefficients between the spherical and cylindrical bases of the oscillator are calculated. It is shown that the relevant coefficients are expressed through the generalised hypergeometric functions $_4F_3$ of the unit argument or $6_j$ Racah symbols extended over their indices to the region of real values. Limiting transitions to a free motion and flat space are considered in detail. Elliptic bases of the oscillator are constructed in the form of expansion over the spherical and cylindrical bases. The corresponding expansion coefficients are shown to obey the three-term recurrence relations., Comment: 21 pages, LaTex

Published
1997

49. Chiral And Parity Anomalies At Finite Temperature And Density

Author

Sissakian, A. N., Shevchenko, O. Yu., and Solganik, S. B.

Subjects
High Energy Physics - Theory
Abstract

Two closely related topological phenomena are studied at finite density and temperature. These are chiral anomaly and Chern-Simons term. By using different methods it is shown that $\mu^2 = m^2$ is the crucial point for Chern-Simons at zero temperature. So when $\mu^2 < m^2$ $\mu$--influence disappears and we get the usual Chern-Simons term. On the other hand when $\mu^2 > m^2$ the Chern-Simons term vanishes because of non-zero density of background fermions. It is occurs that the chiral anomaly doesn't depend on density and temperature. The connection between parity anomalous Chern-Simons and chiral anomaly is generalized on finite density. These results hold in any dimension as in abelian, so as in nonabelian cases.

Published
1997
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