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1. Transverse-spin-dependent azimuthal asymmetries of pion and kaon pairs produced in muon-proton and muon-deuteron semi-inclusive deep inelastic scattering

Author

G.D. Alexeev, M.G. Alexeev, C. Alice, A. Amoroso, V. Andrieux, V. Anosov, K. Augsten, W. Augustyniak, C.D.R. Azevedo, B. Badelek, J. Barth, R. Beck, Y. Bedfer, J. Bernhard, M. Bodlak, F. Bradamante, C. Braun, A. Bressan, V.E. Burtsev, W.-C. Chang, C. Chatterjee, M. Chiosso, A.G. Chumakov, S.-U. Chung, A. Cicuttin, P.M.M. Correia, M.L. Crespo, D. D'Ago, S. Dalla Torre, S.S. Dasgupta, S. Dasgupta, F. Del Carro, I. Denisenko, O.Yu. Denisov, S.V. Donskov, N. Doshita, Ch. Dreisbach, W. Dünnweber, R.R. Dusaev, D. Ecker, A. Efremov, C. Elia, D. Eremeev, P. Faccioli, M. Faessler, M. Finger, M. Finger, jr., H. Fischer, K.J. Flöthner, W. Florian, J.M. Friedrich, V. Frolov, L.G. Garcia Ordòñez, F. Gautheron, O.P. Gavrichtchouk, S. Gerassimov, J. Giarra, D. Giordano, M. Gorzellik, A. Grasso, A. Gridin, M. Grosse Perdekamp, B. Grube, M. Grüner, A. Guskov, D. von Harrach, M. Hoffmann, N. Horikawa, N. d'Hose, C.-Y. Hsieh, S. Huber, S. Ishimoto, A. Ivanov, T. Iwata, M. Jandek, V. Jary, R. Joosten, E. Kabuß, F. Kaspar, A. Kerbizi, B. Ketzer, A. Khatun, G.V. Khaustov, F. Klein, J.H. Koivuniemi, V.N. Kolosov, K. Kondo Horikawa, I. Konorov, V.F. Konstantinov, A.M. Korzenev, A.M. Kotzinian, O.M. Kouznetsov, A. Koval, Z. Kral, F. Krinner, F. Kunne, K. Kurek, R.P. Kurjata, A. Kveton, K. Lavickova, S. Levorato, Y.-S. Lian, J. Lichtenstadt, P.-J. Lin, R. Longo, V.E. Lyubovitskij, A. Maggiora, A. Magnon, N. Makins, N. Makke, G.K. Mallot, A. Maltsev, S.A. Mamon, A. Martin, J. Marzec, J. Matoušek, T. Matsuda, G. Mattson, C. Menezes Pires, F. Metzger, M. Meyer, W. Meyer, Yu.V. Mikhailov, M. Mikhasenko, E. Mitrofanov, D. Miura, Y. Miyachi, R. Molina, A. Moretti, A. Nagaytsev, D. Neyret, M. Niemiec, J. Nový, W.-D. Nowak, G. Nukazuka, A.G. Olshevsky, M. Ostrick, D. Panzieri, B. Parsamyan, S. Paul, H. Pekeler, J.-C. Peng, G. Pesaro, M. Pešek, D.V. Peshekhonov, M. Pešková, S. Platchkov, J. Pochodzalla, V.A. Polyakov, M. Quaresma, C. Quintans, G. Reicherz, C. Riedl, D.I. Ryabchikov, A. Rychter, A. Rymbekova, V.D. Samoylenko, A. Sandacz, S. Sarkar, I.A. Savin, G. Sbrizzai, P. Schiavon, H. Schmieden, A. Selyunin, K. Sharko, L. Sinha, M. Slunecka, F. Sozzi, D. Spülbeck, A. Srnka, M. Stolarski, O. Subrt, M. Sulc, H. Suzuki, S. Tessaro, F. Tessarotto, A. Thiel, J. Tomsa, F. Tosello, A. Townsend, T. Triloki, V. Tskhay, B. Valinoti, B.M. Veit, J.F.C.A. Veloso, B. Ventura, M. Virius, M. Wagner, S. Wallner, K. Zaremba, M. Zavertyaev, M. Zemko, E. Zemlyanichkina, and M. Ziembicki

Subjects
SIDIS, Di-hadron, Spin, Fragmentation, Transversity, Collins effect, Physics, QC1-999
Abstract

A set of measurements of azimuthal asymmetries in the production of pairs of identified hadrons in deep-inelastic scattering of muons on transversely polarised 6LiD (deuteron) and NH3 (proton) targets is presented. All available data collected in the years 2003–2004 and 2007/2010 with the COMPASS spectrometer using a muon beam of 160GeV/c at the CERN SPS were analysed. The asymmetries provide access to the transversity distribution functions via a fragmentation function that in principle may be independently obtained from e+e− annihilation data. Results are presented, discussed and compared to existing measurements as well as to model predictions. Asymmetries of π+π− pairs measured with the proton target as a function of the Bjorken scaling variable are sizeable in the range x>0.032, indicating non-vanishing transversity distribution and di-hadron interference fragmentation functions. As already pointed out by several authors, the small asymmetries of π+π− measured on the 6LiD target can be interpreted as indication for a cancellation of u and d-quark transversity distributions.

Published
2023
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2. Collins and Sivers transverse-spin asymmetries in inclusive muoproduction of ρ0 mesons

Author

G.D. Alexeev, M.G. Alexeev, C. Alice, A. Amoroso, V. Andrieux, V. Anosov, K. Augsten, W. Augustyniak, C.D.R. Azevedo, B. Badelek, J. Barth, R. Beck, Y. Bedfer, J. Bernhard, M. Bodlak, F. Bradamante, A. Bressan, V.E. Burtsev, W.-C. Chang, C. Chatterjee, M. Chiosso, A.G. Chumakov, S.-U. Chung, A. Cicuttin, P.M.M. Correia, M.L. Crespo, D. D'Ago, S. Dalla Torre, S.S. Dasgupta, S. Dasgupta, F. Del Carro, I. Denisenko, O.Yu. Denisov, S.V. Donskov, N. Doshita, Ch. Dreisbach, W. Dünnweber, R.R. Dusaev, D. Ecker, A. Efremov, C. Elia, D. Eremeev, P. Faccioli, M. Faessler, M. Finger, M. Finger, jr., H. Fischer, K.J. Flöthner, W. Florian, J.M. Friedrich, V. Frolov, L.G. Garcia Ordòñez, F. Gautheron, O.P. Gavrichtchouk, S. Gerassimov, J. Giarra, D. Giordano, M. Gorzellik, A. Grasso, A. Gridin, M. Grosse Perdekamp, B. Grube, M. Grüner, A. Guskov, D. von Harrach, M. Hoffmann, N. Horikawa, N. d'Hose, C.-Y. Hsieh, S. Huber, S. Ishimoto, A. Ivanov, T. Iwata, M. Jandek, V. Jary, R. Joosten, E. Kabuß, F. Kaspar, A. Kerbizi, B. Ketzer, A. Khatun, G.V. Khaustov, F. Klein, J.H. Koivuniemi, V.N. Kolosov, K. Kondo Horikawa, I. Konorov, V.F. Konstantinov, A.M. Korzenev, A.M. Kotzinian, O.M. Kouznetsov, A. Koval, Z. Kral, F. Krinner, F. Kunne, K. Kurek, R.P. Kurjata, A. Kveton, K. Lavickova, S. Levorato, Y.-S. Lian, J. Lichtenstadt, P.-J. Lin, R. Longo, V.E. Lyubovitskij, A. Maggiora, A. Magnon, N. Makins, N. Makke, G.K. Mallot, A. Maltsev, S.A. Mamon, A. Martin, J. Marzec, J. Matoušek, T. Matsuda, G. Mattson, C. Menezes Pires, F. Metzger, M. Meyer, W. Meyer, Yu.V. Mikhailov, M. Mikhasenko, E. Mitrofanov, D. Miura, Y. Miyachi, R. Molina, A. Moretti, A. Nagaytsev, C. Naim, D. Neyret, J. Nový, W.-D. Nowak, G. Nukazuka, A.G. Olshevsky, M. Ostrick, D. Panzieri, B. Parsamyan, S. Paul, H. Pekeler, J.-C. Peng, M. Pešek, D.V. Peshekhonov, M. Pešková, S. Platchkov, J. Pochodzalla, V.A. Polyakov, M. Quaresma, C. Quintans, G. Reicherz, C. Riedl, T. Rudnicki, D.I. Ryabchikov, A. Rychter, A. Rymbekova, V.D. Samoylenko, A. Sandacz, S. Sarkar, I.A. Savin, G. Sbrizzai, H. Schmieden, A. Selyunin, K. Sharko, L. Sinha, M. Slunecka, F. Sozzi, D. Spülbeck, A. Srnka, M. Stolarski, O. Subrt, M. Sulc, H. Suzuki, S. Tessaro, F. Tessarotto, A. Thiel, J. Tomsa, F. Tosello, A. Townsend, T. Triloki, V. Tskhay, B. Valinoti, B.M. Veit, J.F.C.A. Veloso, B. Ventura, M. Virius, M. Wagner, S. Wallner, K. Zaremba, M. Zavertyaev, M. Zemko, E. Zemlyanichkina, and M. Ziembicki

Subjects
SIDIS, Spin, Fragmentation, Collins asymmetry, Sivers asymmetry, Physics, QC1-999
Abstract

The production of vector mesons in deep inelastic scattering is an interesting yet scarcely explored channel to study the transverse spin structure of the nucleon and the spin-dependence of fragmentation. The COMPASS collaboration has performed the first measurement of the Collins and Sivers asymmetries for inclusively produced ρ0 mesons. The analysis is based on the data set collected in deep inelastic scattering in 2010 using a 160GeV/c μ+ beam impinging on a transversely polarized NH3 target. The ρ0 mesons are selected from oppositely charged hadron pairs, and the asymmetries are extracted as a function of the Bjorken-x variable, the transverse momentum of the pair and the fraction of the energy z carried by the pair. Indications for positive Collins and Sivers asymmetries are observed.

Published
2023
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3. Double J/ψ production in pion-nucleon scattering at COMPASS

Author

G.D. Alexeev, M.G. Alexeev, A. Amoroso, V. Andrieux, V. Anosov, K. Augsten, W. Augustyniak, C.D.R. Azevedo, B. Badełek, M. Ball, J. Barth, R. Beck, Y. Bedfer, J. Bernhard, M. Bodlak, F. Bradamante, A. Bressan, V.E. Burtsev, W.-C. Chang, C. Chatterjee, M. Chiosso, A.G. Chumakov, S.-U. Chung, A. Cicuttin, P.M.M. Correia, M.L. Crespo, D. D'Ago, S. Dalla Torre, S.S. Dasgupta, S. Dasgupta, I. Denisenko, O.Yu. Denisov, S.V. Donskov, N. Doshita, Ch. Dreisbach, W. Dünnweber, R.R. Dusaev, D. Ecker, A. Efremov, D. Eremeev, P.D. Eversheim, P. Faccioli, M. Faessler, M. Finger, M. Finger, jr., H. Fischer, K.J. Flöthner, W. Florian, C. Franco, J.M. Friedrich, V. Frolov, L.G. Garcia Ordòñez, F. Gautheron, O.P. Gavrichtchouk, S. Gerassimov, J. Giarra, D. Giordano, M. Gorzellik, A. Grasso, A. Gridin, S. Groote, M. Grosse Perdekamp, B. Grube, M. Grüner, A. Guskov, D. von Harrach, M. Hoffmann, N. Horikawa, N. d'Hose, C.-Y. Hsieh, S. Huber, S. Ishimoto, A. Ivanov, T. Iwata, M. Jandek, V. Jary, R. Joosten, E. Kabuß, F. Kaspar, A. Kerbizi, B. Ketzer, A. Khatun, G.V. Khaustov, Yu.A. Khokhlov, F. Klein, J.H. Koivuniemi, V.N. Kolosov, K. Kondo Horikawa, I. Konorov, V.F. Konstantinov, A.M. Korzenev, S. Koshkarev, A.M. Kotzinian, O.M. Kouznetsov, A. Koval, Z. Kral, F. Krinner, F. Kunne, K. Kurek, R.P. Kurjata, A. Kveton, K. Lavickova, S. Levorato, Y.-S. Lian, J. Lichtenstadt, P.-J. Lin, R. Longo, V.E. Lyubovitskij, A. Maggiora, A. Magnon, N. Makins, N. Makke, G.K. Mallot, A. Maltsev, S.A. Mamon, A. Martin, J. Marzec, J. Matoušek, T. Matsuda, G. Mattson, C. Menezes Pires, F. Metzger, M. Meyer, W. Meyer, Yu.V. Mikhailov, M. Mikhasenko, E. Mitrofanov, Y. Miyachi, R. Molina, A. Moretti, A. Nagaytsev, C. Naim, D. Neyret, J. Nový, W.-D. Nowak, G. Nukazuka, A.G. Olshevsky, M. Ostrick, D. Panzieri, B. Parsamyan, S. Paul, H. Pekeler, J.-C. Peng, M. Pešek, D.V. Peshekhonov, M. Pešková, S. Platchkov, J. Pochodzalla, V.A. Polyakov, J. Pretz, M. Quaresma, C. Quintans, G. Reicherz, C. Riedl, T. Rudnicki, D.I. Ryabchikov, A. Rychter, A. Rymbekova, V.D. Samoylenko, A. Sandacz, S. Sarkar, I.A. Savin, G. Sbrizzai, H. Schmieden, A. Selyunin, K. Sharko, L. Sinha, M. Slunecka, D. Spülbeck, A. Srnka, M. Stolarski, O. Subrt, M. Sulc, H. Suzuki, S. Tessaro, F. Tessarotto, A. Thiel, J. Tomsa, F. Tosello, A. Townsend, T. Triloki, V. Tskhay, B. Valinoti, B.M. Veit, J.F.C.A. Veloso, B. Ventura, M. Virius, M. Wagner, S. Wallner, K. Zaremba, M. Zavertyaev, M. Zemko, E. Zemlyanichkina, and M. Ziembicki

Subjects
COMPASS, Charmonia production, Double J/ψ, Single parton scattering, Intrinsic charm, Physics, QC1-999
Abstract

We present the study of the production of double J/ψ mesons using COMPASS data collected with a 190 GeV/c π− beam scattering off NH3, Al and W targets. Kinematic distributions of the collected double J/ψ events are analysed, and the double J/ψ production cross section is estimated for each of the COMPASS targets. The NH3 results are compared to predictions from single- and double-parton scattering models as well as the pion intrinsic charm and the tetraquark exotic resonance hypotheses. It is demonstrated that the single parton scattering production mechanism gives the dominant contribution that is sufficient to describe the data. An upper limit on the double intrinsic charm content of the pion is evaluated. No significant signatures that could be associated with exotic tetraquarks are found in the double J/ψ mass spectrum.

Published
2023
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4. Probing transversity by measuring Λ polarisation in SIDIS

Author

G.D. Alexeev, M.G. Alexeev, A. Amoroso, V. Andrieux, V. Anosov, K. Augsten, W. Augustyniak, C.D.R. Azevedo, B. Badełek, F. Balestra, M. Ball, J. Barth, R. Beck, Y. Bedfer, J. Berenguer Antequera, J. Bernhard, M. Bodlak, F. Bradamante, A. Bressan, V.E. Burtsev, W.-C. Chang, C. Chatterjee, M. Chiosso, A.G. Chumakov, S.-U. Chung, A. Cicuttin, P.M.M. Correia, M.L. Crespo, D. D'Ago, S. Dalla Torre, S.S. Dasgupta, S. Dasgupta, I. Denisenko, O.Yu. Denisov, S.V. Donskov, N. Doshita, Ch. Dreisbach, W. Dünnweber, R.R. Dusaev, A. Efremov, C. Elia, D. Eremeev, P.D. Eversheim, P. Faccioli, M. Faessler, A. Ferrero, M. Finger, M. Finger, jr., H. Fischer, K.J. Flöthner, C. Franco, J.M. Friedrich, V. Frolov, L.G. Garcia Ordòñez, F. Gautheron, O.P. Gavrichtchouk, S. Gerassimov, J. Giarra, D. Giordano, I. Gnesi, M. Gorzellik, A. Grasso, A. Gridin, M. Grosse Perdekamp, B. Grube, A. Guskov, D. von Harrach, R. Heitz, M. Hoffmann, N. Horikawa, N. d'Hose, C.-Y. Hsieh, S. Huber, S. Ishimoto, A. Ivanov, T. Iwata, M. Jandek, V. Jary, R. Joosten, E. Kabuß, D.-H. Kang, F. Kaspar, A. Kerbizi, B. Ketzer, G.V. Khaustov, Yu.A. Khokhlov, Yu. Kisselev, F. Klein, J.H. Koivuniemi, V.N. Kolosov, K. Kondo Horikawa, I. Konorov, V.F. Konstantinov, A.M. Kotzinian, O.M. Kouznetsov, A. Koval, Z. Kral, F. Krinner, Y. Kulinich, F. Kunne, K. Kurek, R.P. Kurjata, A. Kveton, K. Lavickova, S. Levorato, Y.-S. Lian, J. Lichtenstadt, P.-J. Lin, R. Longo, V.E. Lyubovitskij, A. Maggiora, A. Magnon, N. Makins, N. Makke, G.K. Mallot, A. Maltsev, S.A. Mamon, B. Marianski, A. Martin, J. Marzec, J. Matoušek, T. Matsuda, G. Mattson, G.V. Meshcheryakov, F. Metzger, M. Meyer, W. Meyer, Yu.V. Mikhailov, M. Mikhasenko, E. Mitrofanov, Y. Miyachi, A. Moretti, A. Nagaytsev, C. Naim, T.S. Negrini, D. Neyret, J. Nový, W.-D. Nowak, G. Nukazuka, A.S. Nunes, A.G. Olshevsky, M. Ostrick, D. Panzieri, B. Parsamyan, S. Paul, H. Pekeler, J.-C. Peng, M. Pešek, D.V. Peshekhonov, M. Pešková, N. Pierre, S. Platchkov, J. Pochodzalla, V.A. Polyakov, J. Pretz, M. Quaresma, C. Quintans, G. Reicherz, C. Riedl, T. Rudnicki, D.I. Ryabchikov, A. Rychter, A. Rymbekova, V.D. Samoylenko, A. Sandacz, S. Sarkar, I.A. Savin, G. Sbrizzai, P. Schiavon, H. Schmieden, A. Selyunin, K. Sharko, L. Sinha, M. Slunecka, J. Smolik, F. Sozzi, A. Srnka, D. Steffen, M. Stolarski, O. Subrt, M. Sulc, H. Suzuki, P. Sznajder, S. Tessaro, F. Tessarotto, A. Thiel, J. Tomsa, F. Tosello, A. Townsend, V. Tskhay, S. Uhl, B.I. Vasilishin, A. Vauth, B.M. Veit, J. Veloso, B. Ventura, A. Vidon, M. Virius, M. Wagner, S. Wallner, K. Zaremba, P. Zavada, M. Zavertyaev, M. Zemko, E. Zemlyanichkina, Y. Zhao, and M. Ziembicki

Subjects
Quantum chromodynamics, Deep inelastic scattering, Lambda polarisation, Transversity, COMPASS, Physics, QC1-999
Abstract

Based on the observation of sizeable target-transverse-spin asymmetries in single-hadron and hadron-pair production in Semi-Inclusive measurements of Deep Inelastic Scattering (SIDIS), the chiral-odd transversity quark distribution functions h1q are nowadays well established. Several possible channels to access these functions were originally proposed. One candidate is the measurement of the polarisation of Λ hyperons produced in SIDIS off transversely polarised nucleons, where the transverse polarisation of the struck quark might be transferred to the final-state hyperon. In this article, we present the COMPASS results on the transversity-induced polarisation of Λ and Λ¯ hyperons produced in SIDIS off transversely polarised protons. Within the experimental uncertainties, no significant deviation from zero was observed. The results are discussed in the context of different models taking into account previous experimental results on h1u and h1d.

Published
2022
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5. Transverse extension of partons in the proton probed in the sea-quark range by measuring the DVCS cross section

Author

R. Akhunzyanov, M.G. Alexeev, G.D. Alexeev, A. Amoroso, V. Andrieux, N.V. Anfimov, V. Anosov, A. Antoshkin, K. Augsten, W. Augustyniak, A. Austregesilo, C.D.R. Azevedo, B. Badełek, F. Balestra, M. Ball, J. Barth, R. Beck, Y. Bedfer, J. Bernhard, K. Bicker, E.R. Bielert, R. Birsa, M. Bodlak, P. Bordalo, F. Bradamante, A. Bressan, M. Büchele, E. Burtin, V.E. Burtsev, W.-C. Chang, C. Chatterjee, M. Chiosso, I. Choi, A.G. Chumakov, S.-U. Chung, A. Cicuttin, M.L. Crespo, S. Dalla Torre, S.S. Dasgupta, S. Dasgupta, O.Yu. Denisov, L. Dhara, S.V. Donskov, N. Doshita, Ch. Dreisbach, W. Dünnweber, R.R. Dusaev, M. Dziewiecki, A. Efremov, P.D. Eversheim, M. Faessler, A. Ferrero, M. Finger, M. Finger, jr., H. Fischer, C. Franco, N. du Fresne von Hohenesche, J.M. Friedrich, V. Frolov, E. Fuchey, F. Gautheron, O.P. Gavrichtchouk, S. Gerassimov, J. Giarra, I. Gnesi, M. Gorzellik, A. Grasso, A. Gridin, M. Grosse Perdekamp, B. Grube, T. Grussenmeyer, A. Guskov, D. Hahne, G. Hamar, D. von Harrach, R. Heitz, F. Herrmann, N. Horikawa, N. d'Hose, C.-Y. Hsieh, S. Huber, S. Ishimoto, A. Ivanov, Yu. Ivanshin, T. Iwata, V. Jary, R. Joosten, P. Jörg, K. Juraskova, E. Kabuß, A. Kerbizi, B. Ketzer, G.V. Khaustov, Yu.A. Khokhlov, Yu. Kisselev, F. Klein, J.H. Koivuniemi, V.N. Kolosov, K. Kondo, I. Konorov, V.F. Konstantinov, A.M. Kotzinian, O.M. Kouznetsov, Z. Kral, M. Krämer, F. Krinner, Z.V. Kroumchtein, Y. Kulinich, F. Kunne, K. Kurek, R.P. Kurjata, I.I. Kuznetsov, A. Kveton, A.A. Lednev, E.A. Levchenko, M. Levillain, S. Levorato, Y.-S. Lian, J. Lichtenstadt, R. Longo, V.E. Lyubovitskij, A. Maggiora, A. Magnon, N. Makins, N. Makke, G.K. Mallot, S.A. Mamon, B. Marianski, A. Martin, J. Marzec, J. Matoušek, H. Matsuda, T. Matsuda, G.V. Meshcheryakov, M. Meyer, W. Meyer, Yu.V. Mikhailov, M. Mikhasenko, E. Mitrofanov, N. Mitrofanov, Y. Miyachi, A. Moretti, A. Nagaytsev, F. Nerling, D. Neyret, J. Nový, W.-D. Nowak, G. Nukazuka, A.S. Nunes, A.G. Olshevsky, I. Orlov, M. Ostrick, D. Panzieri, B. Parsamyan, S. Paul, J.-C. Peng, F. Pereira, M. Pešek, M. Pešková, D.V. Peshekhonov, N. Pierre, S. Platchkov, J. Pochodzalla, V.A. Polyakov, J. Pretz, M. Quaresma, C. Quintans, S. Ramos, C. Regali, G. Reicherz, C. Riedl, N.S. Rogacheva, D.I. Ryabchikov, A. Rybnikov, A. Rychter, R. Salac, V.D. Samoylenko, A. Sandacz, C. Santos, S. Sarkar, I.A. Savin, T. Sawada, G. Sbrizzai, P. Schiavon, H. Schmieden, K. Schönning, E. Seder, A. Selyunin, L. Silva, L. Sinha, S. Sirtl, M. Slunecka, J. Smolik, A. Srnka, D. Steffen, M. Stolarski, O. Subrt, M. Sulc, H. Suzuki, A. Szabelski, T. Szameitat, P. Sznajder, M. Tasevsky, S. Tessaro, F. Tessarotto, A. Thiel, J. Tomsa, F. Tosello, V. Tskhay, S. Uhl, B.I. Vasilishin, A. Vauth, B.M. Veit, J. Veloso, A. Vidon, M. Virius, S. Wallner, M. Wilfert, J. ter Wolbeek, K. Zaremba, P. Zavada, M. Zavertyaev, E. Zemlyanichkina, N. Zhuravlev, and M. Ziembicki

Subjects
Physics, QC1-999
Abstract

We report on the first measurement of exclusive single-photon muoproduction on the proton by COMPASS using 160GeV/c polarised μ+ and μ− beams of the CERN SPS impinging on a liquid hydrogen target. We determine the dependence of the average of the measured μ+ and μ− cross sections for deeply virtual Compton scattering on the squared four-momentum transfer t from the initial to the final proton. The slope B of the t-dependence is fitted with a single exponential function, which yields B=(4.3±0.6stat|sys−0.3+0.1)(GeV/c)−2. This result can be converted into a transverse extension of partons in the proton, 〈r⊥2〉=(0.58±0.04stat|sys−0.02+0.01±0.04model)fm. For this measurement, the average virtuality of the photon mediating the interaction is 〈Q2〉=1.8(GeV/c)2 and the average value of the Bjorken variable is 〈xBj〉=0.056. Keywords: Quantum chromodynamics, Deep inelastic scattering, Exclusive reactions, Deeply virtual Compton scattering, Generalized Parton Distributions, Proton size, COMPASS

Published
2019
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6. Measurement of PT-weighted Sivers asymmetries in leptoproduction of hadrons

Author

M.G. Alexeev, G.D. Alexeev, A. Amoroso, V. Andrieux, N.V. Anfimov, V. Anosov, A. Antoshkin, K. Augsten, W. Augustyniak, C.D.R. Azevedo, B. Badełek, F. Balestra, M. Ball, J. Barth, V. Barone, R. Beck, Y. Bedfer, J. Bernhard, K. Bicker, E.R. Bielert, M. Bodlak, P. Bordalo, F. Bradamante, A. Bressan, M. Büchele, V.E. Burtsev, W.-C. Chang, C. Chatterjee, M. Chiosso, A.G. Chumakov, S.-U. Chung, A. Cicuttin, M.L. Crespo, S. Dalla Torre, S.S. Dasgupta, S. Dasgupta, O.Yu. Denisov, L. Dhara, S.V. Donskov, N. Doshita, Ch. Dreisbach, W. Dünnweber, R.R. Dusaev, M. Dziewiecki, A. Efremov, C. Elia, P.D. Eversheim, M. Faessler, A. Ferrero, M. Finger, M. Finger, jr., H. Fischer, C. Franco, N. du Fresne von Hohenesche, J.M. Friedrich, V. Frolov, F. Gautheron, O.P. Gavrichtchouk, S. Gerassimov, J. Giarra, I. Gnesi, M. Gorzellik, A. Grasso, A. Gridin, M. Grosse Perdekamp, B. Grube, A. Guskov, D. Hahne, G. Hamar, D. von Harrach, R. Heitz, F. Herrmann, N. Horikawa, N. d'Hose, C.-Y. Hsieh, S. Huber, S. Ishimoto, A. Ivanov, T. Iwata, M. Jandek, V. Jary, R. Joosten, P. Jörg, K. Juraskova, E. Kabuß, F. Kaspar, A. Kerbizi, B. Ketzer, G.V. Khaustov, Yu.A. Khokhlov, Yu. Kisselev, F. Klein, J.H. Koivuniemi, V.N. Kolosov, K. Kondo, I. Konorov, V.F. Konstantinov, A.M. Kotzinian, O.M. Kouznetsov, Z. Kral, M. Krämer, F. Krinner, Z.V. Kroumchtein, Y. Kulinich, F. Kunne, K. Kurek, R.P. Kurjata, A. Kveton, A.A. Lednev, S. Levorato, Y.-S. Lian, J. Lichtenstadt, R. Longo, V.E. Lyubovitskij, A. Maggiora, A. Magnon, N. Makins, N. Makke, G.K. Mallot, S.A. Mamon, B. Marianski, A. Martin, J. Marzec, J. Matoušek, T. Matsuda, G.V. Meshcheryakov, M. Meyer, W. Meyer, Yu.V. Mikhailov, M. Mikhasenko, E. Mitrofanov, N. Mitrofanov, Y. Miyachi, A. Moretti, A. Nagaytsev, D. Neyret, J. Nový, W.-D. Nowak, G. Nukazuka, A.S. Nunes, A.G. Olshevsky, I. Orlov, M. Ostrick, D. Panzieri, B. Parsamyan, S. Paul, J.-C. Peng, F. Pereira, M. Pešek, M. Pešková, D.V. Peshekhonov, N. Pierre, S. Platchkov, J. Pochodzalla, V.A. Polyakov, J. Pretz, M. Quaresma, C. Quintans, S. Ramos, C. Regali, G. Reicherz, C. Riedl, D.I. Ryabchikov, A. Rybnikov, A. Rychter, R. Salac, V.D. Samoylenko, A. Sandacz, S. Sarkar, I.A. Savin, T. Sawada, G. Sbrizzai, P. Schiavon, H. Schmieden, E. Seder, A. Selyunin, L. Silva, L. Sinha, S. Sirtl, M. Slunecka, J. Smolik, F. Sozzi, A. Srnka, D. Steffen, M. Stolarski, O. Subrt, M. Sulc, H. Suzuki, A. Szabelski, T. Szameitat, P. Sznajder, M. Tasevsky, S. Tessaro, F. Tessarotto, A. Thiel, J. Tomsa, F. Tosello, V. Tskhay, S. Uhl, B.I. Vasilishin, A. Vauth, B.M. Veit, J. Veloso, A. Vidon, M. Virius, M. Wagner, S. Wallner, M. Wilfert, K. Zaremba, P. Zavada, M. Zavertyaev, Y. Zhao, E. Zemlyanichkina, and M. Ziembicki

Subjects
Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract

The transverse spin asymmetries measured in semi-inclusive leptoproduction of hadrons, when weighted with the hadron transverse momentum PT, allow for the extraction of important transverse-momentum-dependent distribution functions. In particular, the weighted Sivers asymmetries provide direct information on the Sivers function, which is a leading-twist distribution that arises from a correlation between the transverse momentum of an unpolarised quark in a transversely polarised nucleon and the spin of the nucleon. Using the high-statistics data collected by the COMPASS Collaboration in 2010 with a transversely polarised proton target, we have evaluated two types of PT-weighted Sivers asymmetries, which are both proportional to the product of the first transverse moment of the Sivers function and of the fragmentation function. The results are compared to the standard unweighted Sivers asymmetries and used to extract the first transverse moments of the Sivers distributions for u and d quarks.

Published
2019
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7. Antiproton over proton and K− over K+ multiplicity ratios at high z in DIS

Author

G.D. Alexeev, M.G. Alexeev, A. Amoroso, V. Andrieux, V. Anosov, A. Antoshkin, K. Augsten, W. Augustyniak, C.D.R. Azevedo, B. Badełek, F. Balestra, M. Ball, J. Barth, R. Beck, Y. Bedfer, J. Berenguer Antequera, J. Bernhard, M. Bodlak, F. Bradamante, A. Bressan, M. Büchele, V.E. Burtsev, W.-C. Chang, C. Chatterjee, M. Chiosso, A.G. Chumakov, S.-U. Chung, A. Cicuttin, P.M.M. Correia, M.L. Crespo, D. D'Ago, S. Dalla Torre, S.S. Dasgupta, S. Dasgupta, I. Denisenko, O.Yu. Denisov, S.V. Donskov, N. Doshita, Ch. Dreisbach, W. Dünnweber, R.R. Dusaev, A. Efremov, P.D. Eversheim, P. Faccioli, M. Faessler, M. Finger, M. Finger, jr., H. Fischer, C. Franco, J.M. Friedrich, V. Frolov, F. Gautheron, O.P. Gavrichtchouk, S. Gerassimov, J. Giarra, I. Gnesi, M. Gorzellik, A. Grasso, A. Gridin, M. Grosse Perdekamp, B. Grube, A. Guskov, D. von Harrach, R. Heitz, F. Herrmann, N. Horikawa, N. d'Hose, C.-Y. Hsieh, S. Huber, S. Ishimoto, A. Ivanov, T. Iwata, M. Jandek, V. Jary, R. Joosten, P. Jörg, E. Kabuß, F. Kaspar, A. Kerbizi, B. Ketzer, G.V. Khaustov, Yu.A. Khokhlov, Yu. Kisselev, F. Klein, J.H. Koivuniemi, V.N. Kolosov, K. Kondo Horikawa, I. Konorov, V.F. Konstantinov, A.M. Kotzinian, O.M. Kouznetsov, A. Koval, Z. Kral, F. Krinner, Y. Kulinich, F. Kunne, K. Kurek, R.P. Kurjata, A. Kveton, K. Lavičková, S. Levorato, Y.-S. Lian, J. Lichtenstadt, P.-J. Lin, R. Longo, V.E. Lyubovitskij, A. Maggiora, A. Magnon, N. Makins, N. Makke, G.K. Mallot, A. Maltsev, S.A. Mamon, B. Marianski, A. Martin, J. Marzec, J. Matoušek, T. Matsuda, G. Mattson, G.V. Meshcheryakov, M. Meyer, W. Meyer, Yu.V. Mikhailov, M. Mikhasenko, E. Mitrofanov, N. Mitrofanov, Y. Miyachi, A. Moretti, A. Nagaytsev, C. Naim, D. Neyret, J. Nový, W.-D. Nowak, G. Nukazuka, A.S. Nunes, A.G. Olshevsky, M. Ostrick, D. Panzieri, B. Parsamyan, S. Paul, H. Pekeler, J.-C. Peng, M. Pešek, D.V. Peshekhonov, M. Pešková, N. Pierre, S. Platchkov, J. Pochodzalla, V.A. Polyakov, J. Pretz, M. Quaresma, C. Quintans, G. Reicherz, C. Riedl, T. Rudnicki, D.I. Ryabchikov, A. Rybnikov, A. Rychter, V.D. Samoylenko, A. Sandacz, S. Sarkar, I.A. Savin, G. Sbrizzai, H. Schmieden, A. Selyunin, L. Sinha, M. Slunecka, J. Smolik, A. Srnka, D. Steffen, M. Stolarski, O. Subrt, M. Sulc, H. Suzuki, P. Sznajder, S. Tessaro, F. Tessarotto, A. Thiel, J. Tomsa, F. Tosello, A. Townsend, V. Tskhay, S. Uhl, B.I. Vasilishin, A. Vauth, B.M. Veit, J. Veloso, B. Ventura, A. Vidon, M. Virius, M. Wagner, S. Wallner, K. Zaremba, P. Zavada, M. Zavertyaev, M. Zemko, E. Zemlyanichkina, Y. Zhao, and M. Ziembicki

Subjects
Quantum chromodynamics, pQCD, Deep-inelastic scattering, Hadron multiplicities, COMPASS, Physics, QC1-999
Abstract

The antiparticle-over-particle multiplicity ratio is measured in deep-inelastic scattering for negatively and positively charged kaons and, for the first time, for antiprotons and protons. The data were obtained by the COMPASS Collaboration using a 160 GeV muon beam impinging on an isoscalar 6LiD target. The regime of deep-inelastic scattering is ensured by requiring Q2 > 1 (GeV/c)2 for the photon virtuality and W>5 GeV/c2 for the invariant mass of the produced hadronic system. Bjorken-x is restricted to the range 0.01 to 0.40. Protons and antiprotons are identified in the momentum range from 20 GeV/c to 60 GeV/c and required to carry a large fraction of the virtual-photon energy, z>0.5. In the whole studied z-region, the p¯ over p multiplicity ratio is found to be below the lower limit expected from calculations based on leading-order perturbative Quantum Chromodynamics (pQCD). Kaons were previously analysed in the momentum range 12 GeV/c to 40 GeV/c. In the present analysis this range is extended up to 55 GeV/c, whereby events with larger virtual-photon energies are included in the analysis and the observed K− over K+ ratio becomes closer to the expectation of next-to-leading order pQCD. The results of both analyses strengthen our earlier conclusion that at COMPASS energies the phase space available for single-hadron production in deep-inelastic scattering should be taken into account in the standard pQCD formalism.

Published
2020
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8. Contribution of exclusive diffractive processes to the measured azimuthal asymmetries in SIDIS

Author

J. Agarwala, M.G. Alexeev, G.D. Alexeev, A. Amoroso, V. Andrieux, N.V. Anfimov, V. Anosov, A. Antoshkin, K. Augsten, W. Augustyniak, C.D.R. Azevedo, B. Badełek, F. Balestra, M. Ball, J. Barth, R. Beck, Y. Bedfer, J. Berenguer Antequera, J. Bernhard, M. Bodlak, P. Bordalo, F. Bradamante, A. Bressan, M. Büchele, V.E. Burtsev, W.-C. Chang, C. Chatterjee, M. Chiosso, A.G. Chumakov, S.-U. Chung, A. Cicuttin, P.M.M. Correia, M.L. Crespo, D. D'Ago, S. Dalla Torre, S.S. Dasgupta, S. Dasgupta, I. Denisenko, O.Yu. Denisov, L. Dhara, S.V. Donskov, N. Doshita, Ch. Dreisbach, W. Dünnweber, R.R. Dusaev, A. Efremov, P.D. Eversheim, M. Faessler, A. Ferrero, M. Finger, M. Finger, Jr., H. Fischer, C. Franco, J.M. Friedrich, V. Frolov, F. Gautheron, O.P. Gavrichtchouk, S. Gerassimov, J. Giarra, I. Gnesi, M. Gorzellik, A. Grasso, A. Gridin, M. Grosse Perdekamp, B. Grube, A. Guskov, D. von Harrach, R. Heitz, F. Herrmann, N. Horikawa, N. d'Hose, C.-Y. Hsieh, S. Huber, S. Ishimoto, A. Ivanov, T. Iwata, M. Jandek, V. Jary, R. Joosten, P. Jörg, E. Kabuß, F. Kaspar, A. Kerbizi, B. Ketzer, G.V. Khaustov, Yu.A. Khokhlov, Yu. Kisselev, F. Klein, J.H. Koivuniemi, V.N. Kolosov, K. Kondo Horikawa, I. Konorov, V.F. Konstantinov, A.M. Kotzinian, O.M. Kouznetsov, A. Koval, Z. Kral, F. Krinner, Y. Kulinich, F. Kunne, K. Kurek, R.P. Kurjata, A. Kveton, K. Lavickova, S. Levorato, Y.-S. Lian, J. Lichtenstadt, P.-J. Lin, R. Longo, V.E. Lyubovitskij, A. Maggiora, A. Magnon, N. Makins, N. Makke, G.K. Mallot, A. Maltsev, S.A. Mamon, B. Marianski, A. Martin, J. Marzec, J. Matoušek, T. Matsuda, G. Mattson, G.V. Meshcheryakov, M. Meyer, W. Meyer, Yu.V. Mikhailov, M. Mikhasenko, E. Mitrofanov, N. Mitrofanov, Y. Miyachi, A. Moretti, A. Nagaytsev, C. Naim, D. Neyret, J. Nový, W.-D. Nowak, G. Nukazuka, A.S. Nunes, A.G. Olshevsky, M. Ostrick, D. Panzieri, B. Parsamyan, S. Paul, H. Pekeler, J.-C. Peng, F. Pereira, M. Pešek, D.V. Peshekhonov, M. Pešková, N. Pierre, S. Platchkov, J. Pochodzalla, V.A. Polyakov, J. Pretz, M. Quaresma, C. Quintans, S. Ramos, G. Reicherz, C. Riedl, T. Rudnicki, D.I. Ryabchikov, A. Rybnikov, A. Rychter, V.D. Samoylenko, A. Sandacz, S. Sarkar, I.A. Savin, G. Sbrizzai, H. Schmieden, A. Selyunin, L. Sinha, M. Slunecka, J. Smolik, A. Srnka, D. Steffen, M. Stolarski, O. Subrt, M. Sulc, H. Suzuki, A. Szabelski, P. Sznajder, S. Tessaro, F. Tessarotto, A. Thiel, J. Tomsa, F. Tosello, A. Townsend, V. Tskhay, S. Uhl, B.I. Vasilishin, A. Vauth, B.M. Veit, J. Veloso, B. Ventura, A. Vidon, M. Virius, M. Wagner, S. Wallner, M. Wilfert, K. Zaremba, P. Zavada, M. Zavertyaev, M. Zemko, E. Zemlyanichkina, Y. Zhao, and M. Ziembicki

Subjects
Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract

Hadron leptoproduction in Semi-Inclusive measurements of Deep-Inelastic Scattering (SIDIS) on unpolarised nucleons allows one to get information on the intrinsic transverse momentum of quarks in a nucleon and on the Boer-Mulders function through the measurement of azimuthal modulations in the cross section. These modulations were recently measured by the HERMES experiment at DESY on proton and deuteron targets, and by the COMPASS experiment using the CERN SPS muon beam and a 6LiD target. In both cases, the amplitudes of the cos⁡ϕh and cos⁡2ϕh modulations show strong kinematic dependences for both positive and negative hadrons. It has been known since some time that the measured final-state hadrons in those SIDIS experiments receive a contribution from exclusive diffractive production of vector mesons, particularly important at large values of z, the fraction of the virtual photon energy carried by the hadron. In previous measurements of azimuthal asymmetries this contribution was not taken into account, because it was not known that it could distort the azimuthal modulations. Presently, a method to evaluate the contribution of the exclusive reactions to the azimuthal asymmetries measured by COMPASS has been developed. The subtraction of this contribution results in a better understanding of the kinematic effects, and the remaining non-zero cos⁡2ϕh modulation gives indication for a non-zero Boer-Mulders effect.

Published
2020
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9. Measurement of the cross section for hard exclusive π0 muoproduction on the proton

Author

M.G. Alexeev, G.D. Alexeev, A. Amoroso, V. Andrieux, N.V. Anfimov, V. Anosov, A. Antoshkin, K. Augsten, W. Augustyniak, C.D.R. Azevedo, B. Badełek, F. Balestra, M. Ball, J. Barth, R. Beck, Y. Bedfer, J. Bernhard, M. Bodlak, P. Bordalo, F. Bradamante, A. Bressan, M. Büchele, V.E. Burtsev, W.-C. Chang, C. Chatterjee, M. Chiosso, A.G. Chumakov, S.-U. Chung, A. Cicuttin, M.L. Crespo, S. Dalla Torre, S.S. Dasgupta, S. Dasgupta, O.Yu. Denisov, L. Dhara, S.V. Donskov, N. Doshita, Ch. Dreisbach, W. Dünnweber, R.R. Dusaev, A. Efremov, P.D. Eversheim, M. Faessler, A. Ferrero, M. Finger, M. Finger, Jr., H. Fischer, C. Franco, N. du Fresne von Hohenesche, J.M. Friedrich, V. Frolov, E. Fuchey, F. Gautheron, O.P. Gavrichtchouk, S. Gerassimov, J. Giarra, I. Gnesi, M. Gorzellik, A. Grasso, A. Gridin, M. Grosse Perdekamp, B. Grube, A. Guskov, D. Hahne, G. Hamar, D. von Harrach, R. Heitz, F. Herrmann, N. Horikawa, N. d'Hose, C.-Y. Hsieh, S. Huber, S. Ishimoto, A. Ivanov, T. Iwata, M. Jandek, V. Jary, R. Joosten, P. Jörg, K. Juraskova, E. Kabuß, F. Kaspar, A. Kerbizi, B. Ketzer, G.V. Khaustov, Yu.A. Khokhlov, Yu. Kisselev, F. Klein, J.H. Koivuniemi, V.N. Kolosov, K. Kondo Horikawa, I. Konorov, V.F. Konstantinov, A.M. Kotzinian, O.M. Kouznetsov, Z. Kral, M. Krämer, F. Krinner, Z.V. Kroumchtein, Y. Kulinich, F. Kunne, K. Kurek, R.P. Kurjata, A. Kveton, S. Levorato, Y.-S. Lian, J. Lichtenstadt, P.-J. Lin, R. Longo, V.E. Lyubovitskij, A. Maggiora, A. Magnon, N. Makins, N. Makke, G.K. Mallot, S.A. Mamon, B. Marianski, A. Martin, J. Marzec, J. Matoušek, T. Matsuda, G.V. Meshcheryakov, M. Meyer, W. Meyer, Yu.V. Mikhailov, M. Mikhasenko, E. Mitrofanov, N. Mitrofanov, Y. Miyachi, A. Moretti, C. Naim, A. Nagaytsev, D. Neyret, J. Nový, W.-D. Nowak, G. Nukazuka, A.S. Nunes, A.G. Olshevsky, M. Ostrick, D. Panzieri, B. Parsamyan, S. Paul, J.-C. Peng, F. Pereira, M. Pešek, D.V. Peshekhonov, M. Pešková, N. Pierre, S. Platchkov, J. Pochodzalla, V.A. Polyakov, J. Pretz, M. Quaresma, C. Quintans, S. Ramos, C. Regali, G. Reicherz, C. Riedl, D.I. Ryabchikov, A. Rybnikov, A. Rychter, V.D. Samoylenko, A. Sandacz, S. Sarkar, I.A. Savin, G. Sbrizzai, H. Schmieden, A. Selyunin, L. Silva, L. Sinha, M. Slunecka, J. Smolik, A. Srnka, D. Steffen, M. Stolarski, O. Subrt, M. Sulc, H. Suzuki, A. Szabelski, T. Szameitat, P. Sznajder, S. Tessaro, F. Tessarotto, A. Thiel, J. Tomsa, F. Tosello, V. Tskhay, S. Uhl, B.I. Vasilishin, A. Vauth, B.M. Veit, J. Veloso, A. Vidon, M. Virius, M. Wagner, S. Wallner, M. Wilfert, K. Zaremba, P. Zavada, M. Zavertyaev, E. Zemlyanichkina, Y. Zhao, and M. Ziembicki

Subjects
Quantum chromodynamics, Muoproduction, Hard exclusive meson production, Generalised Parton Distributions, COMPASS, Physics, QC1-999
Abstract

We report on a measurement of hard exclusive π0 muoproduction on the proton by COMPASS using 160GeV/c polarised μ+ and μ− beams of the CERN SPS impinging on a liquid hydrogen target. From the average of the measured μ+ and μ− cross sections, the virtual-photon proton cross section is determined as a function of the squared four-momentum transfer between initial and final proton in the range 0.08(GeV/c)2

Published
2020
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10. K− over K+ multiplicity ratio for kaons produced in DIS with a large fraction of the virtual-photon energy

Author

R. Akhunzyanov, M.G. Alexeev, G.D. Alexeev, A. Amoroso, V. Andrieux, N.V. Anfimov, V. Anosov, A. Antoshkin, K. Augsten, W. Augustyniak, A. Austregesilo, C.D.R. Azevedo, B. Badełek, F. Balestra, M. Ball, J. Barth, R. Beck, Y. Bedfer, J. Bernhard, K. Bicker, E.R. Bielert, R. Birsa, M. Bodlak, P. Bordalo, F. Bradamante, A. Bressan, M. Büchele, V.E. Burtsev, L. Capozza, W.-C. Chang, C. Chatterjee, M. Chiosso, A.G. Chumakov, S.-U. Chung, A. Cicuttin, M.L. Crespo, Q. Curiel, S. Dalla Torre, S.S. Dasgupta, S. Dasgupta, O.Yu. Denisov, L. Dhara, S.V. Donskov, N. Doshita, Ch. Dreisbach, W. Dünnweber, R.R. Dusaev, M. Dziewiecki, A. Efremov, P.D. Eversheim, M. Faessler, A. Ferrero, M. Finger, M. Finger, jr., H. Fischer, C. Franco, N. du Fresne von Hohenesche, J.M. Friedrich, V. Frolov, F. Gautheron, O.P. Gavrichtchouk, S. Gerassimov, J. Giarra, I. Gnesi, M. Gorzellik, A. Grasso, A. Gridin, M. Grosse Perdekamp, B. Grube, A. Guskov, D. Hahne, G. Hamar, D. von Harrach, R. Heitz, F. Herrmann, N. Horikawa, N. d'Hose, C.-Y. Hsieh, S. Huber, S. Ishimoto, A. Ivanov, T. Iwata, V. Jary, R. Joosten, P. Jörg, E. Kabuß, A. Kerbizi, B. Ketzer, G.V. Khaustov, Yu.A. Khokhlov, Yu. Kisselev, F. Klein, J.H. Koivuniemi, V.N. Kolosov, K. Kondo, I. Konorov, V.F. Konstantinov, A.M. Kotzinian, O.M. Kouznetsov, Z. Kral, M. Krämer, F. Krinner, Z.V. Kroumchtein, Y. Kulinich, F. Kunne, K. Kurek, R.P. Kurjata, I.I. Kuznetsov, A. Kveton, A.A. Lednev, E.A. Levchenko, S. Levorato, Y.-S. Lian, J. Lichtenstadt, R. Longo, V.E. Lyubovitskij, A. Maggiora, A. Magnon, N. Makins, N. Makke, G.K. Mallot, S.A. Mamon, C. Marchand, B. Marianski, A. Martin, J. Marzec, J. Matoušek, H. Matsuda, T. Matsuda, G.V. Meshcheryakov, M. Meyer, W. Meyer, Yu.V. Mikhailov, M. Mikhasenko, E. Mitrofanov, N. Mitrofanov, Y. Miyachi, A. Moretti, A. Nagaytsev, F. Nerling, D. Neyret, J. Nový, W.-D. Nowak, G. Nukazuka, A.S. Nunes, A.G. Olshevsky, I. Orlov, M. Ostrick, D. Panzieri, B. Parsamyan, S. Paul, J.-C. Peng, F. Pereira, G. Pesaro, M. Pešek, M. Pešková, D.V. Peshekhonov, N. Pierre, S. Platchkov, J. Pochodzalla, V.A. Polyakov, J. Pretz, M. Quaresma, C. Quintans, S. Ramos, C. Regali, G. Reicherz, C. Riedl, D.I. Ryabchikov, A. Rybnikov, A. Rychter, R. Salac, V.D. Samoylenko, A. Sandacz, S. Sarkar, I.A. Savin, T. Sawada, G. Sbrizzai, P. Schiavon, H. Schmieden, E. Seder, A. Selyunin, L. Silva, L. Sinha, S. Sirtl, M. Slunecka, F. Sozzi, J. Smolik, A. Srnka, D. Steffen, M. Stolarski, O. Subrt, M. Sulc, H. Suzuki, A. Szabelski, T. Szameitat, P. Sznajder, M. Tasevsky, S. Tessaro, F. Tessarotto, A. Thiel, J. Tomsa, F. Tosello, V. Tskhay, S. Uhl, B.I. Vasilishin, A. Vauth, B.M. Veit, J. Veloso, A. Vidon, M. Virius, S. Wallner, M. Wilfert, R. Windmolders, K. Zaremba, P. Zavada, M. Zavertyaev, E. Zemlyanichkina, and M. Ziembicki

Subjects
Physics, QC1-999
Abstract

The K− over K+ multiplicity ratio is measured in deep-inelastic scattering, for the first time for kaons carrying a large fraction z of the virtual-photon energy. The data were obtained by the COMPASS collaboration using a 160 GeV muon beam and an isoscalar 6LiD target. The regime of deep-inelastic scattering is ensured by requiring Q2>1(GeV/c)2 for the photon virtuality and W>5GeV/c2 for the invariant mass of the produced hadronic system. Kaons are identified in the momentum range from 12 GeV/c to 40 GeV/c, thereby restricting the range in Bjorken-x to 0.010.75. For very large values of z, i.e. z>0.8, we observe the kaon multiplicity ratio to fall below the lower limits expected from calculations based on leading and next-to-leading order perturbative quantum chromodynamics. Also, the kaon multiplicity ratio shows a strong dependence on the missing mass of the single-kaon production process. This suggests that within the perturbative quantum chromodynamics formalism an additional correction may be required, which takes into account the phase space available for hadronisation.

Published
2018
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11. Longitudinal double-spin asymmetry A1p and spin-dependent structure function g1p of the proton at small values of x and Q2

Author

M. Aghasyan, M.G. Alexeev, G.D. Alexeev, A. Amoroso, V. Andrieux, N.V. Anfimov, V. Anosov, A. Antoshkin, K. Augsten, W. Augustyniak, A. Austregesilo, C.D.R. Azevedo, B. Badełek, F. Balestra, M. Ball, J. Barth, R. Beck, Y. Bedfer, J. Bernhard, K. Bicker, E.R. Bielert, R. Birsa, M. Bodlak, P. Bordalo, F. Bradamante, A. Bressan, M. Büchele, V.E. Burtsev, L. Capozza, W.-C. Chang, C. Chatterjee, M. Chiosso, I. Choi, A.G. Chumakov, S.-U. Chung, A. Cicuttin, M.L. Crespo, S. Dalla Torre, S.S. Dasgupta, S. Dasgupta, O.Yu. Denisov, L. Dhara, S.V. Donskov, N. Doshita, Ch. Dreisbach, W. Dünnweber, R.R. Dusaev, M. Dziewiecki, A. Efremov, P.D. Eversheim, M. Faessler, A. Ferrero, M. Finger, M. Finger, jr., H. Fischer, C. Franco, N. du Fresne von Hohenesche, J.M. Friedrich, V. Frolov, E. Fuchey, F. Gautheron, O.P. Gavrichtchouk, S. Gerassimov, J. Giarra, F. Giordano, I. Gnesi, M. Gorzellik, A. Grasso, A. Gridin, M. Grosse Perdekamp, B. Grube, T. Grussenmeyer, A. Guskov, D. Hahne, G. Hamar, D. von Harrach, F.H. Heinsius, R. Heitz, F. Herrmann, N. Horikawa, N. d'Hose, C.-Y. Hsieh, S. Huber, S. Ishimoto, A. Ivanov, T. Iwata, V. Jary, R. Joosten, P. Jörg, E. Kabuß, A. Kerbizi, B. Ketzer, G.V. Khaustov, Yu.A. Khokhlov, Yu. Kisselev, F. Klein, J.H. Koivuniemi, V.N. Kolosov, K. Kondo, K. Königsmann, I. Konorov, V.F. Konstantinov, A.M. Kotzinian, O.M. Kouznetsov, Z. Kral, M. Krämer, P. Kremser, F. Krinner, Z.V. Kroumchtein, Y. Kulinich, F. Kunne, K. Kurek, R.P. Kurjata, I.I. Kuznetsov, A. Kveton, A.A. Lednev, E.A. Levchenko, M. Levillain, S. Levorato, Y.-S. Lian, J. Lichtenstadt, R. Longo, V.E. Lyubovitskij, A. Maggiora, A. Magnon, N. Makins, N. Makke, G.K. Mallot, S.A. Mamon, B. Marianski, A. Martin, J. Marzec, J. Matoušek, H. Matsuda, T. Matsuda, G.V. Meshcheryakov, M. Meyer, W. Meyer, Yu.V. Mikhailov, M. Mikhasenko, E. Mitrofanov, N. Mitrofanov, Y. Miyachi, A. Moretti, A. Nagaytsev, F. Nerling, D. Neyret, J. Nový, W.-D. Nowak, G. Nukazuka, A.S. Nunes, A.G. Olshevsky, I. Orlov, M. Ostrick, D. Panzieri, B. Parsamyan, S. Paul, J.-C. Peng, F. Pereira, M. Pešek, M. Pešková, D.V. Peshekhonov, N. Pierre, S. Platchkov, J. Pochodzalla, V.A. Polyakov, J. Pretz, M. Quaresma, C. Quintans, S. Ramos, C. Regali, G. Reicherz, C. Riedl, N.S. Rogacheva, D.I. Ryabchikov, A. Rybnikov, A. Rychter, R. Salac, V.D. Samoylenko, A. Sandacz, C. Santos, S. Sarkar, I.A. Savin, T. Sawada, G. Sbrizzai, P. Schiavon, K. Schmidt, H. Schmieden, K. Schönning, E. Seder, A. Selyunin, L. Silva, L. Sinha, S. Sirtl, M. Slunecka, J. Smolik, A. Srnka, D. Steffen, M. Stolarski, O. Subrt, M. Sulc, H. Suzuki, A. Szabelski, T. Szameitat, P. Sznajder, M. Tasevsky, S. Tessaro, F. Tessarotto, A. Thiel, J. Tomsa, F. Tosello, V. Tskhay, S. Uhl, B.I. Vasilishin, A. Vauth, J. Veloso, A. Vidon, M. Virius, S. Wallner, T. Weisrock, M. Wilfert, R. Windmolders, J. ter Wolbeek, K. Zaremba, P. Zavada, M. Zavertyaev, E. Zemlyanichkina, and M. Ziembicki

Subjects
Physics, QC1-999
Abstract

We present a precise measurement of the proton longitudinal double-spin asymmetry A1p and the proton spin-dependent structure function g1p at photon virtualities 0.006(GeV/c)2

Published
2018
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12. New analysis of ηπ tensor resonances measured at the COMPASS experiment

Author

A. Jackura, C. Fernández-Ramírez, M. Mikhasenko, A. Pilloni, V. Mathieu, J. Nys, V. Pauk, A.P. Szczepaniak, G. Fox, M. Aghasyan, R. Akhunzyanov, M.G. Alexeev, G.D. Alexeev, A. Amoroso, V. Andrieux, N.V. Anfimov, V. Anosov, A. Antoshkin, K. Augsten, W. Augustyniak, A. Austregesilo, C.D.R. Azevedo, B. Badełek, F. Balestra, M. Ball, J. Barth, R. Beck, Y. Bedfer, J. Bernhard, K. Bicker, E.R. Bielert, R. Birsa, M. Bodlak, P. Bordalo, F. Bradamante, A. Bressan, M. Büchele, V.E. Burtsev, W.-C. Chang, C. Chatterjee, M. Chiosso, I. Choi, A.G. Chumakov, S.-U. Chung, A. Cicuttin, M.L. Crespo, S. Dalla Torre, S.S. Dasgupta, S. Dasgupta, O.Yu. Denisov, L. Dhara, S.V. Donskov, N. Doshita, Ch. Dreisbach, W. Dünnweber, R.R. Dusaev, M. Dziewiecki, A. Efremov, P.D. Eversheim, M. Faessler, A. Ferrero, M. Finger, M. Finger, jr., H. Fischer, C. Franco, N. du Fresne von Hohenesche, J.M. Friedrich, V. Frolov, E. Fuchey, F. Gautheron, O.P. Gavrichtchouk, S. Gerassimov, J. Giarra, F. Giordano, I. Gnesi, M. Gorzellik, A. Grasso, M. Grosse Perdekamp, B. Grube, T. Grussenmeyer, A. Guskov, D. Hahne, G. Hamar, D. von Harrach, F.H. Heinsius, R. Heitz, F. Herrmann, N. Horikawa, N. d'Hose, C.-Y. Hsieh, S. Huber, S. Ishimoto, A. Ivanov, Yu. Ivanshin, T. Iwata, V. Jary, R. Joosten, P. Jörg, E. Kabuß, A. Kerbizi, B. Ketzer, G.V. Khaustov, Yu.A. Khokhlov, Yu. Kisselev, F. Klein, J.H. Koivuniemi, V.N. Kolosov, K. Kondo, K. Königsmann, I. Konorov, V.F. Konstantinov, A.M. Kotzinian, O.M. Kouznetsov, Z. Kral, M. Krämer, P. Kremser, F. Krinner, Z.V. Kroumchtein, Y. Kulinich, F. Kunne, K. Kurek, R.P. Kurjata, I.I. Kuznetsov, A. Kveton, A.A. Lednev, E.A. Levchenko, M. Levillain, S. Levorato, Y.-S. Lian, J. Lichtenstadt, R. Longo, V.E. Lyubovitskij, A. Maggiora, A. Magnon, N. Makins, N. Makke, G.K. Mallot, S.A. Mamon, B. Marianski, A. Martin, J. Marzec, J. Matoušek, H. Matsuda, T. Matsuda, G.V. Meshcheryakov, M. Meyer, W. Meyer, Yu.V. Mikhailov, E. Mitrofanov, N. Mitrofanov, Y. Miyachi, A. Nagaytsev, F. Nerling, D. Neyret, J. Nový, W.-D. Nowak, G. Nukazuka, A.S. Nunes, A.G. Olshevsky, I. Orlov, M. Ostrick, D. Panzieri, B. Parsamyan, S. Paul, J.-C. Peng, F. Pereira, M. Pešek, M. Pešková, D.V. Peshekhonov, N. Pierre, S. Platchkov, J. Pochodzalla, V.A. Polyakov, J. Pretz, M. Quaresma, C. Quintans, S. Ramos, C. Regali, G. Reicherz, C. Riedl, N.S. Rogacheva, D.I. Ryabchikov, A. Rybnikov, A. Rychter, R. Salac, V.D. Samoylenko, A. Sandacz, C. Santos, S. Sarkar, I.A. Savin, T. Sawada, G. Sbrizzai, P. Schiavon, T. Schlüter, K. Schmidt, H. Schmieden, K. Schönning, E. Seder, A. Selyunin, L. Silva, L. Sinha, S. Sirtl, M. Slunecka, J. Smolik, A. Srnka, D. Steffen, M. Stolarski, O. Subrt, M. Sulc, H. Suzuki, A. Szabelski, T. Szameitat, P. Sznajder, M. Tasevsky, S. Tessaro, F. Tessarotto, A. Thiel, J. Tomsa, F. Tosello, V. Tskhay, S. Uhl, B.I. Vasilishin, A. Vauth, J. Veloso, A. Vidon, M. Virius, S. Wallner, T. Weisrock, M. Wilfert, J. ter Wolbeek, K. Zaremba, P. Zavada, M. Zavertyaev, E. Zemlyanichkina, N. Zhuravlev, and M. Ziembicki

Subjects
Physics, QC1-999
Abstract

We present a new amplitude analysis of the ηπ D-wave in the reaction π−p→ηπ−p measured by COMPASS. Employing an analytical model based on the principles of the relativistic S-matrix, we find two resonances that can be identified with the a2(1320) and the excited a2′(1700), and perform a comprehensive analysis of their pole positions. For the mass and width of the a2 we find M=(1307±1±6) MeV and Γ=(112±1±8) MeV, and for the excited state a2′ we obtain M=(1720±10±60) MeV and Γ=(280±10±70) MeV, respectively.

Published
2018
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13. Improved exclusion limit for light dark matter from e+e− annihilation in NA64

Author

V. M. Lysan, Vassili Kachanov, S. N. Gninenko, André Rubbia, M. Jeckel, V. A. Kramarenko, L. Kravchuk, D. Shchukin, A. N. Toropin, M. Bondi, V.A. Polyakov, P. Ulloa, Johannes Bernhard, Petr Volkov, B. Radics, D. Peshekhonov, Paolo Crivelli, Serguei Kuleshov, L. Molina, V. E. Lyubovitskij, G. D. Kekelidze, V. Volkov, V.E. Burtsev, B.I. Vasilishin, Yu. M. Andreev, V. O. Tikhomirov, G. Vasquez, Rimsky Alejandro Rojas, A. Celentano, V.D. Samoylenko, Sergey Kovalenko, David R. Cooke, R.R. Dusaev, Nikolaos Charitonidis, S. Gerassimov, H. Sieber, Debapriya Banerjee, B. Ketzer, A.G. Chumakov, M. Kirsanov, E. Depero, S. V. Donskov, Igor Konorov, A. V. Dermenev, A. E. Karneyeu, A. Gardikiotis, N. V. Krasnikov, A. Trifonov, V. A. Matveev, I. Tlisova, T. Enik, Yu. V. Mikhailov, V.N. Kolosov, D. V. Kirpichnikov, L. Marsicano, A. Feshchenko, Vladimir Frolov, and M. Hoesgen

Subjects
Physics, Particle physics, Missing energy, Annihilation, 010308 nuclear & particles physics, Dark matter, Electron, Coupling (probability), 01 natural sciences, Standard Model, Vector boson, 0103 physical sciences, 010306 general physics, Light dark matter
Abstract

The current most stringent constraints for the existence of sub-GeV dark matter coupling to Standard Model via a massive vector boson $A^\prime$ were set by the NA64 experiment for the mass region $m_{A^\prime}\lesssim 250$ MeV, by analyzing data from the interaction of $2.84\cdot10^{11}$ 100-GeV electrons with an active thick target and searching for missing-energy events. In this work, by including $A^\prime$ production via secondary positron annihilation with atomic electrons, we extend these limits in the $200$-$300$ MeV region by almost an order of magnitude, touching for the first time the dark matter relic density constrained parameter combinations. Our new results demonstrate the power of the resonant annihilation process in missing energy dark-matter searches, paving the road to future dedicated $e^+$ beam efforts.

Published
2021
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14. Constraints on New Physics in Electron g−2 from a Search for Invisible Decays of a Scalar, Pseudoscalar, Vector, and Axial Vector

Author

B. Radics, Rimsky Alejandro Rojas, S. V. Kuleshov, L. Molina Bueno, Dipanwita Banerjee, A. N. Toropin, A. Yu. Trifonov, B. Ketzer, A. V. Dermenev, Petr Volkov, M. Kirsanov, V. A. Kramarenko, Valery E. Lyubovitskij, L. Kravchuk, Viktor Matveev, V.N. Kolosov, V.D. Samoylenko, V. Yu. Volkov, Sergey Kovalenko, David R. Cooke, E. Depero, Nikolaos Charitonidis, S. Gerassimov, T. Enik, A. Gardikiotis, V.E. Burtsev, V. M. Lysan, N. V. Krasnikov, A.G. Chumakov, Yu Andreev, D. Shchukin, Vassili Kachanov, V. O. Tikhomirov, André Rubbia, Igor Konorov, B.I. Vasilishin, D. V. Kirpichnikov, Paolo Crivelli, R.R. Dusaev, D.V. Peshekhonov, A. Feshchenko, Vladimir Frolov, G. D. Kekelidze, Johannes Bernhard, V.A. Polyakov, M. Hösgen, Sergei Gninenko, H. Sieber, I. Tlisova, Yu. V. Mikhailov, S. V. Donskov, and A. E. Karneyeu

Subjects
Physics, Particle physics, Anomalous magnetic dipole moment, Scalar (mathematics), General Physics and Astronomy, Fine-structure constant, Electron, Coupling (probability), 7. Clean energy, 01 natural sciences, Pseudoscalar, 0103 physical sciences, 010306 general physics, Pseudovector, Boson
Abstract

We performed a search for a new generic X boson, which could be a scalar (S), pseudoscalar (P), vector (V), or an axial vector (A) particle produced in the 100 GeV electron scattering off nuclei, e^{-}Z→e^{-}ZX, followed by its invisible decay in the NA64 experiment at CERN. No evidence for such a process was found in the full NA64 dataset of 2.84×10^{11} electrons on target. We place new bounds on the S, P, V, A coupling strengths to electrons, and set constraints on their contributions to the electron anomalous magnetic moment a_{e}, |Δa_{X}|≲10^{-15}-10^{-13} for the X mass region 1 MeV≲m_{X}≲1 GeV. These results are an order of magnitude more sensitive compared to the current accuracy on a_{e} from the electron g-2 experiments and recent high-precision determination of the fine structure constant.

Published
2021
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15. Spin Density Matrix Elements in Exclusive $\omega$ Meson Muoproduction $^*$

Author

Johannes Bernhard, Ch. Dreisbach, A. Guskov, W.-D. Nowak, C. Quintans, G. Nukazuka, Marcin Stolarski, D. D'Ago, C. Naim, F. Tosello, Pietro Faccioli, P.D. Eversheim, H. Suzuki, C.D.R. Azevedo, A. Srnka, G.V. Meshcheryakov, Yu. V. Mikhailov, Andrea Ferrero, G. D. Alexeev, Franco Bradamante, M. Faessler, P. Jörg, Arseniy Rybnikov, B. Badelek, Norihiro Doshita, N. d'Hose, B.M. Veit, O.P. Gavrichtchouk, Martin Bodlak, B. Ketzer, S. Gerassimov, N. Horikawa, Jen-Chieh Peng, J. Smolik, S.S. Dasgupta, R. Heitz, L. Sinha, O. Subrt, K. Zaremba, H. Schmieden, E. M. Kabuß, S.A. Mamon, T. Matsuda, A. Townsend, J.M. Friedrich, V.A. Polyakov, Y. Miyachi, A. Gridin, D.I. Ryabchikov, S. Sarkar, A.B. Ivanov, V.E. Burtsev, S. Huber, N. Mitrofanov, S. Tessaro, Yakov Petrovich Kulinich, G. Sbrizzai, Alexandr Selyunin, Yuxiang Zhao, A. Vauth, M. Wagner, Alessandro Bressan, D. von Harrach, F. Krinner, E. Zemlyanichkina, M.G. Alexeev, A. Amoroso, Yu.A. Khokhlov, J. Pochodzalla, S. Uhl, O.Yu. Denisov, J. Giarra, D. Neyret, Andres Cicuttin, A. Moretti, V.D. Samoylenko, C. Regali, I.A. Savin, Nour Makke, A. Sandacz, J. Nový, M. Chiosso, Naomi C R Makins, Yu. Kisselev, T. Iwata, R. Joosten, G. Reicherz, A. Maltsev, W. C. Chang, F. Gautheron, A. Vidon, B. Marianski, J. Barth, J.F.C.A. Veloso, A. Rychter, M. Finger, Bakur Parsamyan, J.H. Koivuniemi, K. Kurek, V.N. Kolosov, C. Chatterjee, M. Gorzellik, M. Ostrick, I. Denisenko, S. Dalla Torre, Gerhard K. Mallot, Y.-S. Lian, R. Beck, A. Kerbizi, A. Magnon, M. Quaresma, M. Slunečka, M. Pešková, M. Meyer, M. V. Zavertyaev, O.M. Kouznetsov, Anne-Laure Martin, C.-Y. Hsieh, V. Frolov, H. Pekeler, M. Virius, A.G. Chumakov, Miroslav Sulc, Antonin Kveton, D.V. Peshekhonov, W. Augustyniak, Aram Kotzinian, S. Platchkov, P. Zavada, M. Ziembicki, C. Franco, F. Tessarotto, Soumen Paul, R.P. Kurjata, B.I. Vasilishin, Jan Tomsa, M. Grosse Perdekamp, P.M.M. Correia, I. Konorov, P. Sznajder, J. Pretz, A. Antoshkin, M. Jandek, V.F. Konstantinov, W. Meyer, Maria Liz Crespo, F. Kaspar, D. Steffen, K. Lavickova, A. Grasso, V. Andrieux, A.V. Efremov, I. Gnesi, S. Wallner, Y. Bedfer, R. Longo, Kamil Augsten, V. Jary, S. Ishimoto, H. Fischer, A. Thiel, Valery E. Lyubovitskij, A.G. Olshevsky, G.V. Khaustov, A. Maggiora, S. Levorato, S. Dasgupta, Frank Klein, Jan Matousek, Mikhail Mikhasenko, S. V. Donskov, M. Pešek, F. Kunne, Markus Ball, R.R. Dusaev, V. Tskhay, A.S. Nunes, D. Panzieri, Janusz Marzec, E. Mitrofanov, T. Szameitat, A. Koval, J. Lichtenstadt, B. Ventura, B. Grube, M. Zemko, S.-U. Chung, François Herrmann, P.-J. Lin, K. Kondo Horikawa, G. Mattson, V. Anosov, Z. Kral, J. Berenguer Antequera, W. Dünnweber, A. Nagaytsev, F. Balestra, N. Pierre, T. Rudnicki, C. Riedl, Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, COMPASS, Alexeev, G. D., Alexeev, M. G., Amoroso, A., Andrieux, V., Anosov, V., Antoshkin, A., Augsten, K., Augustyniak, W., Azevedo, C. D. R., Badełek, B., Balestra, F., Ball, M., Barth, J., Beck, R., Bedfer, Y., Antequera, J. Berenguer, Bernhard, J., Bodlak, M., Bradamante, F., Bressan, A., Burtsev, V. E., Chang, W. -C., Chatterjee, C., Chiosso, M., Chumakov, A. G., Chung, S. -U., Cicuttin, A., Correia, P. M. M., Crespo, M. L., D’Ago, D., Torre, S. Dalla, Dasgupta, S. S., Dasgupta, S., Denisenko, I., Denisov, O. Yu., Donskov, S. V., Doshita, N., Dreisbach, Ch., Dünnweber, W., Dusaev, R. R., Efremov, A., Eversheim, P. D., Faccioli, P., Faessler, M., Ferrero, A., Finger, M., Fischer, H., Franco, C., Friedrich, J. M., Frolov, V., Gautheron, F., Gavrichtchouk, O. P., Gerassimov, S., Giarra, J., Gnesi, I., Gorzellik, M., Grasso, A., Gridin, A., Perdekamp, M. Grosse, Grube, B., Guskov, A., von Harrach, D., Heitz, R., Herrmann, F., Horikawa, N., D’Hose, N., Hsieh, C. -Y., Huber, S., Ishimoto, S., Ivanov, A., Iwata, T., Jandek, M., Jary, V., Jörg, P., Joosten, R., Kabuß, E., Kaspar, F., Kerbizi, A., Ketzer, B., Khaustov, G. V., Khokhlov, Yu. A., Kisselev, Yu., Klein, F., Koivuniemi, J. H., Kolosov, V. N., Horikawa, K. Kondo, Konorov, I., Konstantinov, V. F., Kotzinian, A. M., Kouznetsov, O. M., Koval, A., Kral, Z., Krinner, F., Kulinich, Y., Kunne, F., Kurek, K., Kurjata, R. P., Kveton, A., Lavickova, K., Levorato, S., Lian, Y. -S., Lichtenstadt, J., Lin, P. -J., Longo, R., Lyubovitskij, V. E., Maggiora, A., Magnon, A., Makins, N., Makke, N., Mallot, G. K., Maltsev, A., Mamon, S. A., Marianski, B., Martin, A., Marzec, J., Matoušek, J., Matsuda, T., Mattson, G., Meshcheryakov, G. V., Meyer, M., Meyer, W., Mikhailov, Yu. V., Mikhasenko, M., Mitrofanov, E., Mitrofanov, N., Miyachi, Y., Moretti, A., Nagaytsev, A., Naim, C., Neyret, D., Nový, J., Nowak, W. -D., Nukazuka, G., Nunes, A. S., Olshevsky, A. G., Ostrick, M., Panzieri, D., Parsamyan, B., Paul, S., Pekeler, H., Peng, J. -C., Pešek, M., Peshekhonov, D. V., Pešková, M., Pierre, N., Platchkov, S., Pochodzalla, J., Polyakov, V. A., Pretz, J., Quaresma, M., Quintans, C., Regali, C., Reicherz, G., Riedl, C., Rudnicki, T., Ryabchikov, D. I., Rybnikov, A., Rychter, A., Samoylenko, V. D., Sandacz, A., Sarkar, S., Savin, I. A., Sbrizzai, G., Schmieden, H., Selyunin, A., Sinha, L., Slunecka, M., Smolik, J., Srnka, A., Steffen, D., Stolarski, M., Subrt, O., Sulc, M., Suzuki, H., Szameitat, T., Sznajder, P., Tessaro, S., Tessarotto, F., Thiel, A., Tomsa, J., Tosello, F., Townsend, A., Tskhay, V., Uhl, S., Vasilishin, B. I., Vauth, A., Veit, B. M., Veloso, J., Ventura, B., Vidon, A., Virius, M., Wagner, M., Wallner, S., Zaremba, K., Zavada, P., Zavertyaev, M., Zemko, M., Zemlyanichkina, E., Zhao, Y., and Ziembicki, M.

Subjects
virtual [photon], generalized parton distribution, Physics and Astronomy (miscellaneous), Hadron, parton: distribution function, Virtual particle, Parton, SDME, COMPASS, 01 natural sciences, Omega, High Energy Physics - Experiment, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], spin: density matrix, Nuclear Experiment, Quantum chromodynamics, Physics, density matrix [spin], vector meson, helicity: conservation law, Helicity, kinematics, omega(783): production, Production (computer science), distribution function [parton], Particle Physics - Experiment, exclusive reaction, Particle physics, liquid: target [hydrogen], Meson, polarization: longitudinal, lcsh:Astrophysics, +muon+p+omega%28783%29%22">muon p --> muon p omega(783), transverse momentum, meson, hydrogen: liquid: target, lcsh:QB460-466, 0103 physical sciences, polarization: transverse, ddc:530, lcsh:Nuclear and particle physics. Atomic energy. Radioactivity, 010306 general physics, Engineering (miscellaneous), DIS, background, muon: beam, 010308 nuclear & particles physics, hep-ex, High Energy Physics::Phenomenology, conservation law [helicity], Automatic Keywords, lcsh:QC770-798, High Energy Physics::Experiment, experimental results, photon: virtual
Abstract

We report on a measurement of Spin Density Matrix Elements (SDMEs) in hard exclusive $\omega$ meson muoproduction on the proton at COMPASS using 160 GeV/$c$ polarised $ \mu ^{+}$ and $ \mu ^{-}$ beams impinging on a liquid hydrogen target. The measurement covers the range 5.0 GeV/$c^2$ $< W, Comment: 31 pages, 12 figures, 1 appendix

Published
2020
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16. Improved limits on a hypothetical X(16.7) boson and a dark photon decaying into e+e− pairs

Author

P. Ulloa, L. Kravchuk, V. Yu. Volkov, D. Peshekhonov, Serguei Kuleshov, V. A. Matveev, M. Hösgen, D. Shchukin, Rimsky Alejandro Rojas, André Rubbia, V.A. Polyakov, A. Yu. Trifonov, L. Molina Bueno, V. O. Tikhomirov, Paolo Crivelli, V.D. Samoylenko, A. V. Dermenev, V.E. Burtsev, A. N. Toropin, V. E. Lyubovitskij, David R. Cooke, B. Ketzer, V.N. Kolosov, A.G. Chumakov, B.I. Vasilishin, V. M. Lysan, Igor Konorov, S. N. Gninenko, M. Jeckel, R.R. Dusaev, M. Kirsanov, V. A. Kramarenko, Nikolaos Charitonidis, T. Enik, D. A. Tlisov, Sergey Kovalenko, B. Radics, E. Depero, Vassili Kachanov, S. Gerassimov, N. V. Krasnikov, D. V. Kirpichnikov, G. D. Kekelidze, A. Feshchenko, Vladimir Frolov, Johannes Bernhard, A. Gardikiotis, Dipanwita Banerjee, Petr Volkov, G. Vasquez Arenas, S. V. Donskov, A. E. Karneyeu, I. Tlisova, and Yu. V. Mikhailov

Subjects
Physics, Photon, 010308 nuclear & particles physics, Bremsstrahlung, Electron, 01 natural sciences, 7. Clean energy, Super Proton Synchrotron, Dark photon, Excited state, 0103 physical sciences, Anomaly (physics), Atomic physics, 010306 general physics, Boson
Abstract

The improved results on a direct search for a new X ( 16.7 MeV ) boson that could explain the anomalous excess of e + e − pairs observed in the decays of the excited 8 Be ∗ nuclei (“Berillium or X17 anomaly”) are reported. Interestingly, new recent results in the nuclear transitions of another nucleus, 4 He , seems to support this anomaly spurring the need for an independent measurement. If the X boson exists, it could be produced in the bremsstrahlung reaction e − Z → e − Z X by a high energy beam of electrons incident on the active target in the NA64 experiment at the CERN Super Proton Synchrotron and observed through its subsequent decay into e + e − pairs. No evidence for such decays was found from the combined analysis of the data samples with total statistics corresponding to 8.4 × 10 10 electrons on target collected in 2017 and 2018. This allows one to set new limits on the X − e − coupling in the range 1.2 × 10 − 4 ≲ e e ≲ 6.8 × 10 − 4 , excluding part of the parameter space favored by the X17 anomaly, and setting new bounds on the mixing strength of photons with dark photons ( A ′ ) with a mass ≲ 24 MeV . For the 2018 run, the setup was optimized to probe the region of parameter space characterized by a large coupling e . This allowed a significant improvement in sensitivity despite a relatively modest increase in statistics.

Published
2020
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17. K− over K+ multiplicity ratio for kaons produced in DIS with a large fraction of the virtual-photon energy

Author

S. Gerassimov, N. Horikawa, A. Srnka, A.G. Olshevsky, A. Rychter, F. Tosello, S. Tessaro, D. Hahne, R. Longo, M. Wilfert, V.N. Kolosov, L. Capozza, K. Kondo, F. Krinner, Yu.A. Khokhlov, Y.-S. Lian, C. Quintans, Alexandr Selyunin, Andrea Ferrero, I. Konorov, Y. Bedfer, K. Zaremba, C. Regali, C. Chatterjee, T. Sawada, Norihiro Doshita, V.A. Polyakov, Nour Makke, W. C. Chang, N. d'Hose, F. Kunne, Valery E. Lyubovitskij, C. Franco, R.R. Dusaev, V. Tskhay, Z.V. Kroumchtein, M. Chiosso, G. Sbrizzai, M. Quaresma, J. Barth, J. Smolik, E. Seder, J.F.C.A. Veloso, S.A. Mamon, O. Subrt, A. Amoroso, C.-Y. Hsieh, L. Dhara, B. Badełek, M. Ziembicki, Franco Bradamante, F. Pereira, N. du Fresne von Hohenesche, O.M. Kouznetsov, M. Stolarski, T. Szameitat, M. Grosse Perdekamp, B.M. Veit, A. Grasso, A. Gridin, A. Vidon, B. Marianski, Bakur Parsamyan, W. Augustyniak, S. Ramos, D.V. Peshekhonov, G. Pesaro, S. Platchkov, P. Zavada, Maria Liz Crespo, Miroslav Sulc, A. Kveton, Y. Miyachi, A.A. Lednev, P. Schiavon, M. A. Faessler, G.V. Khaustov, V. Frolov, B. Ketzer, Soumen Paul, R. Birsa, Jen-Chieh Peng, J. Lichtenstadt, P. Sznajder, J. Pochodzalla, V. Jary, Anne-Laure Martin, P. Jörg, S.S. Dasgupta, I. Gnesi, H. Schmieden, D. Steffen, Andrew Ivanov, S. Sarkar, Yu. Kisselev, O.P. Gavrichtchouk, Martin Bodlak, J.M. Friedrich, A. Sandacz, A. Vauth, H. Matsuda, R. Salac, M. Ostrick, S. Levorato, L. Sinha, T. Matsuda, D. Neyret, S. Dasgupta, A. Austregesilo, P. Bordalo, R. Akhunzyanov, Laura Silva, V.F. Konstantinov, Yakov Petrovich Kulinich, E.R. Bielert, D.I. Ryabchikov, A. Thiel, Q. Curiel, V.E. Burtsev, N. Mitrofanov, S. Huber, S. Wallner, E.A. Levchenko, S. Ishimoto, D. von Harrach, H. Fischer, E. M. Kabuß, E. Zemlyanichkina, Naomi C R Makins, G. D. Alexeev, R.P. Kurjata, Jan Tomsa, M. V. Zavertyaev, W. Dünnweber, K. Bicker, I.A. Savin, C. Marchand, M. Büchele, M.G. Alexeev, M. Krämer, S. Uhl, M. Finger, G. Hamar, J. Giarra, A.V. Efremov, Ilya Kuznetsov, J.H. Koivuniemi, Michal Dziewiecki, Andres Cicuttin, A. Moretti, I. Orlov, V.D. Samoylenko, Jan Matousek, G. Reicherz, Nikolay Anfimov, M. Pešková, M. Gorzellik, R. Heitz, M. Virius, J. Nový, R. Joosten, O.Yu. Denisov, Z. Kral, S. Dalla Torre, A. Antoshkin, P.D. Eversheim, F. Klein, Kamil Augsten, S.-U. Chung, G.V. Meshcheryakov, H. Suzuki, C.D.R. Azevedo, Yu. V. Mikhailov, R. Beck, A. Kerbizi, S. Sirtl, A. Maggiora, F. Tessarotto, Mikhail Mikhasenko, F. Nerling, François Herrmann, B. Grube, Johannes Bernhard, Ch. Dreisbach, S. V. Donskov, A. Guskov, M. Pešek, A.S. Nunes, Andrea Bressan, Markus Ball, D. Panzieri, Janusz Marzec, M. Tasevsky, E. Mitrofanov, G. Nukazuka, M. Slunecka, A. Magnon, Takahiro Iwata, Federica Sozzi, W. Meyer, K. Kurek, Gerhard K. Mallot, Aram Kotzinian, R. Windmolders, B.I. Vasilishin, M. Meyer, A.G. Chumakov, J. Pretz, Arseniy Rybnikov, W.-D. Nowak, V. Anosov, V. Andrieux, Adam Szabelski, A. Nagaytsev, F. Balestra, N. Pierre, F. Gautheron, C. Riedl, Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, COMPASS, Institut de Recherches sur les lois Fondamentales de l'Univers ( IRFU ), Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Université Paris-Saclay, Akhunzyanov, R., Alexeev, M. G., Alexeev, G. D., Amoroso, A., Andrieux, V., Anfimov, N. V., Anosov, V., Antoshkin, A., Augsten, K., Augustyniak, W., Austregesilo, A., Azevedo, C. D. R., Badełek, B., Balestra, F., Ball, M., Barth, J., Beck, R., Bedfer, Y., Bernhard, J., Bicker, K., Bielert, E. R., Birsa, R., Bodlak, M., Bordalo, P., Bradamante, F., Bressan, A., Büchele, M., Burtsev, V. E., Capozza, L., Chang, W. -C., Chatterjee, C., Chiosso, M., Chumakov, A. G., Chung, S. -U., Cicuttin, A., Crespo, M. L., Curiel, Q., Dalla Torre, S., Dasgupta, S. S., Dasgupta, S., Denisov, O. Yu., Dhara, L., Donskov, S. V., Doshita, N., Dreisbach, Ch., Dünnweber, W., Dusaev, R. R., Dziewiecki, M., Efremov, A., Eversheim, P. D., Faessler, M., Ferrero, A., Finger, M., Fischer, H., Franco, C., du Fresne von Hohenesche, N., Friedrich, J. M., Frolov, V., Gautheron, F., Gavrichtchouk, O. P., Gerassimov, S., Giarra, J., Gnesi, I., Gorzellik, M., Grasso, A., Gridin, A., Grosse Perdekamp, M., Grube, B., Guskov, A., Hahne, D., Hamar, G., von Harrach, D., Heitz, R., Herrmann, F., Horikawa, N., D'Hose, N., Hsieh, C. -Y., Huber, S., Ishimoto, S., Ivanov, A., Iwata, T., Jary, V., Joosten, R., Jörg, P., Kabuß, E., Kerbizi, A., Ketzer, B., Khaustov, G. V., Khokhlov, Yu. A., Kisselev, Yu., Klein, F., Koivuniemi, J. H., Kolosov, V. N., Kondo, K., Konorov, I., Konstantinov, V. F., Kotzinian, A. M., Kouznetsov, O. M., Kral, Z., Krämer, M., Krinner, F., Kroumchtein, Z. V., Kulinich, Y., Kunne, F., Kurek, K., Kurjata, R. P., Kuznetsov, I. I., Kveton, A., Lednev, A. A., Levchenko, E. A., Levorato, S., Lian, Y. -S., Lichtenstadt, J., Longo, R., Lyubovitskij, V. E., Maggiora, A., Magnon, A., Makins, N., Makke, N., Mallot, G. K., Mamon, S. A., Marchand, C., Marianski, B., Martin, A., Marzec, J., Matoušek, J., Matsuda, H., Matsuda, T., Meshcheryakov, G. V., Meyer, M., Meyer, W., Mikhailov, Yu. V., Mikhasenko, M., Mitrofanov, E., Mitrofanov, N., Miyachi, Y., Moretti, A., Nagaytsev, A., Nerling, F., Neyret, D., Nový, J., Nowak, W. -D., Nukazuka, G., Nunes, A. S., Olshevsky, A. G., Orlov, I., Ostrick, M., Panzieri, D., Parsamyan, B., Paul, S., Peng, J. -C., Pereira, F., Pesaro, G., Pešek, M., Pešková, M., Peshekhonov, D. V., Pierre, N., Platchkov, S., Pochodzalla, J., Polyakov, V. A., Pretz, J., Quaresma, M., Quintans, C., Ramos, S., Regali, C., Reicherz, G., Riedl, C., Ryabchikov, D. I., Rybnikov, A., Rychter, A., Salac, R., Samoylenko, V. D., Sandacz, A., Sarkar, S., Savin, I. A., Sawada, T., Sbrizzai, G., Schiavon, P., Schmieden, H., Seder, E., Selyunin, A., Silva, L., Sinha, L., Sirtl, S., Slunecka, M., Sozzi, F., Smolik, J., Srnka, A., Steffen, D., Stolarski, M., Subrt, O., Sulc, M., Suzuki, H., Szabelski, A., Szameitat, T., Sznajder, P., Tasevsky, M., Tessaro, S., Tessarotto, F., Thiel, A., Tomsa, J., Tosello, F., Tskhay, V., Uhl, S., Vasilishin, B. I., Vauth, A., Veit, B. M., Veloso, J., Vidon, A., Virius, M., Wallner, S., Wilfert, M., Windmolders, R., Zaremba, K., Zavada, P., Zavertyaev, M., Zemlyanichkina, E., and Ziembicki, M.

Subjects
Hadron, 0 [higher-order], target: isoscalar, 01 natural sciences, COMPASS, deep inelastic scattering [muon+ nucleon], High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), K: multiplicity, High Energy Physics - Phenomenology (hep-ph), [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], isoscalar [target], Invariant mass, Nuclear Experiment, Boson, Physics, Quantum chromodynamics, quark: fragmentation function, higher-order: 0, photon, perturbation theory: higher-order, hep-ph, мюоны, lcsh:QC1-999, Bjorken [scaling], High Energy Physics - Phenomenology, beam [muon], рассеяние, factorization [cross section], multiplicity [pi], Particle Physics - Experiment, perturbation theory [quantum chromodynamics], Particle physics, Nuclear and High Energy Physics, Meson, FOS: Physical sciences, ratio [multiplicity], fragmentation function [quark], x-dependence, scaling: Bjorken, charged particle: multiplicity, phase space, multiplicity [charged particle], [ PHYS.HEXP ] Physics [physics]/High Energy Physics - Experiment [hep-ex], виртуальные фотоны, 0103 physical sciences, ddc:530, universality, quantum chromodynamics: perturbation theory, 010306 general physics, Particle Physics - Phenomenology, muon+ nucleon: deep inelastic scattering, Muon, multiplicity: ratio, pi: multiplicity, 010308 nuclear & particles physics, hep-ex, muon: beam, Multiplicity (mathematics), cross section: factorization, CERN SPS, Deep inelastic scattering, higher-order [perturbation theory], [PHYS.HPHE]Physics [physics]/High Energy Physics - Phenomenology [hep-ph], каоны, [ PHYS.HPHE ] Physics [physics]/High Energy Physics - Phenomenology [hep-ph], High Energy Physics::Experiment, multiplicity [K], hadronization, lcsh:Physics, experimental results
Abstract

The K$^{-}$ over K$^{+}$ multiplicity ratio is measured in deep-inelastic scattering, for the first time for kaons carrying a large fraction $z$ of the virtual-photon energy. The data were obtained by the COMPASS collaboration using a 160 GeV muon beam and an isoscalar $^6$LiD target. The regime of deep-inelastic scattering is ensured by requiring $Q^2>1$ (GeV/$c)^2$ for the photon virtuality and $W>5$ GeV/$c^2$ for the invariant mass of the produced hadronic system. Kaons are identified in the momentum range from 12 GeV/$c$ to 40 GeV/$c$, thereby restricting the range in Bjorken-$x$ to $0.010.75$. For very large values of $z$, $i.e.$ $z>0.8$, we observe the kaon multiplicity ratio to fall below the lower limits expected from calculations based on leading and next-to-leading order perturbative quantum chromodynamics. Also, the kaon multiplicity ratio shows a strong dependence on the missing mass of the single-kaon production process. This suggests that within the perturbative quantum chromodynamics formalism an additional correction may be required, which takes into account the phase space available for hadronisation., Comment: 16 pages, 7 figures

Published
2018
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18. Search for muoproduction of X(3872) at COMPASS and indication of a new state X˜(3872)

Author

L. Silva, S.S. Dasgupta, A.G. Chumakov, J. Nový, Y. Miyachi, P.D. Eversheim, P. Zavada, E. Zemlyanichkina, François Herrmann, S. Uhl, Y. Bedfer, A. Antoshkin, G. Sbrizzai, N.S. Rogacheva, A. Ferrero, G.V. Khaustov, A. Magnon, F. Pereira, I. Konorov, J. ter Wolbeek, Maria Liz Crespo, C. Regali, J. Marzec, A. Kveton, G.D. Alexeev, K. Schmidt, P. Kremser, O.Yu. Denisov, F. Gautheron, F. Nerling, Yu.A. Khokhlov, K. Kondo, N. C. R. Makins, M. Faessler, V.N. Kolosov, A. Amoroso, H. Matsuda, D. Neyret, C.D.R. Azevedo, V. Jary, V. Anosov, M. Grosse Perdekamp, S. Sarkar, Y.-S. Lian, R. Beck, A. Selyunin, B. Grube, M. Stolarski, M. Tasevsky, T. Sawada, N. Horikawa, M. Sulc, S. Tessaro, D. Hahne, V.D. Samoylenko, J. Giarra, N. d'Hose, W. Meyer, R. Joosten, Andres Cicuttin, O. Subrt, S. Wallner, S. Platchkov, R. Salac, Jen-Chieh Peng, V.A. Polyakov, J. Veloso, N. Zhuravlev, G.V. Meshcheryakov, A. Sandacz, M. Virius, F. H. Heinsius, S. Ishimoto, M. Aghasyan, A.M. Kotzinian, M. Zavertyaev, Jan Matousek, G. Reicherz, S. Dalla Torre, C. Quintans, M. Pešek, J. Barth, Alan D. Martin, M. Chiosso, N.V. Anfimov, Jan Tomsa, M. Ostrick, R.P. Kurjata, M. Finger, E. Kabuß, R.R. Dusaev, A.S. Nunes, T. Weisrock, R. Birsa, K. Augsten, V. Frolov, A. Maggiora, A. Vauth, A.A. Lednev, V.E. Lyubovitskij, C. Chatterjee, P. Jörg, Yakov Petrovich Kulinich, Gerhard K. Mallot, Andrey Ivanov, Frank Klein, P. Bordalo, A. Nagaytsev, Johannes Bernhard, Ch. Dreisbach, D. Panzieri, K. Zaremba, E.R. Bielert, Markus F. Krämer, J. Pochodzalla, K. Königsmann, M. Slunecka, A. Guskov, J.M. Friedrich, A. Srnka, H. Suzuki, S. Dasgupta, B. Marianski, T. Grussenmeyer, A. Rybnikov, Andrea Bressan, Anatoli Vasilievich Efremov, L. Dhara, T. Matsuda, M. Meyer, M. Dziewiecki, Markus Ball, M. Gorzellik, W.-D. Nowak, Yu. Kisselev, P. Schiavon, C. Santos, E. Mitrofanov, Bakur Parsamyan, W. Dünnweber, Martin Bodlak, Yu. Ivanshin, M.G. Alexeev, Ilya Kuznetsov, W. C. Chang, S.V. Donskov, D. Steffen, M. Wilfert, J. Smolik, K. Bicker, S. Ramos, L. Sinha, J. Pretz, E. Fuchey, S. Levorato, A. Austregesilo, A. Gridin, I. J. Choi, N. Mitrofanov, C. Franco, Stephan M. Paul, M. Levillain, A. Thiel, C. Riedl, V. Andrieux, Mikhail Mikhasenko, F. Krinner, I.A. Savin, O.P. Gavrichtchouk, N. Makke, I. Orlov, A. Szabelski, F. Giordano, E.A. Levchenko, N. du Fresne von Hohenesche, S. Gerassimov, N. Pierre, R. Longo, M. Quaresma, N. Doshita, B. Ketzer, A. Vidon, Yu.V. Mikhailov, I. Gnesi, G. Hamar, V.F. Konstantinov, P. Sznajder, Z. Kral, T. Iwata, B.I. Vasilishin, A. Grasso, V. Tskhay, H. Fischer, M. Ziembicki, M. Büchele, A. Rychter, S. Sirtl, Z.V. Kroumchtein, F. Balestra, S.-U. Chung, F. Tosello, T. Szameitat, D. von Harrach, K. Schönning, F. Tessarotto, J.H. Koivuniemi, Franco Bradamante, A. Kerbizi, J. Lichtenstadt, F. Kunne, M. Pešková, E. Seder, K. Kurek, G. Nukazuka, D.V. Peshekhonov, R. Heitz, O.M. Kouznetsov, V.E. Burtsev, R. Akhunzyanov, S.A. Mamon, H. Schmieden, C.-Y. Hsieh, B. Badełek, W. Augustyniak, D.I. Ryabchikov, A.G. Olshevsky, and S. Huber

Subjects
Physics, Nuclear and High Energy Physics, Muon, Mass distribution, 010308 nuclear & particles physics, Branching fraction, Hadron, State (functional analysis), 01 natural sciences, Momentum, 0103 physical sciences, Tetraquark, Atomic physics, 010306 general physics, X(3872)
Abstract

We have searched for exclusive production of exotic charmonia in the reaction μ + N → μ + ( J / ψ π + π − ) π ± N ′ using COMPASS data collected with incoming muons of 160 GeV/c and 200 GeV/c momentum. In the J / ψ π + π − mass distribution we observe a signal with a statistical significance of 4.1 σ. Its mass and width are consistent with those of the X ( 3872 ) . The shape of the π + π − mass distribution from the observed decay into J / ψ π + π − shows disagreement with previous observations for X ( 3872 ) . The observed signal may be interpreted as a possible evidence of a new charmonium state. It could be associated with a neutral partner of X ( 3872 ) with C = − 1 predicted by a tetraquark model. The product of cross section and branching fraction of the decay of the observed state into J / ψ π + π − is determined to be 71±28(stat)±39(syst) pb.

Published
2018
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20. Hunting down the X17 boson at the CERN SPS

Author

T. Enik, Dipanwita Banerjee, L. Molina Bueno, D. Shchukin, V. E. Lyubovitskij, V.D. Samoylenko, Petr Volkov, David R. Cooke, V. A. Kramarenko, M. Kirsanov, P. Ulloa, Nikolaos Charitonidis, A. Yu. Trifonov, Serguei Kuleshov, N. V. Krasnikov, B. Radics, B. Ketzer, V.N. Kolosov, Paolo Crivelli, V. O. Tikhomirov, André Rubbia, S. V. Donskov, A.G. Chumakov, S. Girod, Igor Konorov, A. E. Karneyeu, D. V. Kirpichnikov, vI. Tlisova, V.A. Polyakov, Rimsky Alejandro Rojas, V. A. Matveev, D. A. Tlisov, Sergey Kovalenko, A. Feshchenko, Vladimir Frolov, Yu. V. Mikhailov, E. Depero, A. V. Dermenev, V.E. Burtsev, H. Sieber, G. Vasquez Arenas, Vassili Kachanov, M. Hösgen, G. D. Kekelidze, L. Kravchuk, V. Yu. Volkov, Johannes Bernhard, V. M. Lysan, D. Peshekhonov, B.I. Vasilishin, Yu. M. Andreev, S. Gerassimov, S. N. Gninenko, R.R. Dusaev, A. Gardikiotis, and A. N. Toropin

Subjects
Particle physics, Physics - Instrumentation and Detectors, Physics and Astronomy (miscellaneous), Regular Article - Experimental Physics, Monte Carlo method, Dark matter, FOS: Physical sciences, lcsh:Astrophysics, Parameter space, Tracking (particle physics), 01 natural sciences, High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), 0103 physical sciences, lcsh:QB460-466, Dark Matter, Invariant mass, lcsh:Nuclear and particle physics. Atomic energy. Radioactivity, Sensitivity (control systems), Detectors and Experimental Techniques, 010306 general physics, physics.ins-det, Engineering (miscellaneous), Bosons, Boson, Physics, Large Hadron Collider, hep-ex, 010308 nuclear & particles physics, Instrumentation and Detectors (physics.ins-det), Missing Mass (Astrophysics), lcsh:QC770-798, Particle Physics - Experiment
Abstract

Recently, the ATOMKI experiment has reported new evidence for the excess of e+e- events with a mass ∼ 17 MeV in the nuclear transitions of 4He, that they previously observed in measurements with 8Be. These observations could be explained by the existence of a new vector X17 boson. So far, the search for the decay X17 → e+e- with the NA64 experiment at the CERN SPS gave negative results. Here, we present a new technique that could be implemented in NA64 aiming to improve the sensitivity and to cover the remaining X17 parameter space. If a signal-like event is detected, an unambiguous observation is achieved by reconstructing the invariant mass of the X17 decay with the proposed method. To reach this goal an optimization of the X17 production target, as well as an efficient and accurate reconstruction of two close decay tracks, is required. A dedicated analysis of the available experimental data making use of the trackers information is presented. This method provides independent confirmation of the NA64 published results [1], validating the tracking procedure. The detailed Monte Carlo study of the proposed setup and the background estimate show that the goal of the proposed search is feasible., The European Physical Journal C, 80 (12), ISSN:1434-6044, ISSN:1434-6052

Published
2020
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21. Antiproton over proton and K$^-$ over K$^+$ multiplicity ratios at high $z$ in DIS

Author

G. D. Alexeev, W. Dünnweber, R. Heitz, O.Yu. Denisov, A. Gridin, M. A. Faessler, W.-D. Nowak, R. Beck, A. Kerbizi, G.V. Meshcheryakov, A. Srnka, Yu. V. Mikhailov, F. Kunne, M. Grosse Perdekamp, C.-Y. Hsieh, V. Frolov, Soumen Paul, A. Grasso, W. Augustyniak, Miroslav Sulc, P. Sznajder, D.V. Peshekhonov, O.P. Gavrichtchouk, Martin Bodlak, L. Sinha, T. Matsuda, G. Nukazuka, A. Townsend, D. Steffen, A. Thiel, M. Stolarski, Yu. Kisselev, Pietro Faccioli, F. Tessarotto, Jan Tomsa, M.G. Alexeev, S. Uhl, A.V. Efremov, J. Giarra, I. Gnesi, M. Ostrick, Franco Bradamante, V. Anosov, M. Mikhasenko, A. Rychter, J. Lichtenstadt, Andres Cicuttin, A. Moretti, K. Zaremba, V.D. Samoylenko, V.A. Polyakov, V.N. Kolosov, A.G. Olshevsky, A. Maltsev, M. Quaresma, A.B. Ivanov, Alexandr Selyunin, I. Denisenko, S. Dalla Torre, G. Sbrizzai, M. Zemko, A. Amoroso, Arseniy Rybnikov, Nour Makke, W. C. Chang, D. Neyret, C. Chatterjee, Y. Miyachi, D. D'Ago, C. Naim, Yuxiang Zhao, Johannes Bernhard, Ch. Dreisbach, A. Guskov, B.M. Veit, R.R. Dusaev, M. V. Zavertyaev, V. Tskhay, Anne-Laure Martin, A. Sandacz, Antonin Kveton, C. Franco, B. Badelek, D.I. Ryabchikov, F. Tosello, K. Kondo Horikawa, M. Meyer, G. Mattson, A.G. Chumakov, B. Ketzer, E. M. Kabuß, C. Quintans, V.F. Konstantinov, S. Wallner, Norihiro Doshita, N. d'Hose, J.F.C.A. Veloso, Yakov Petrovich Kulinich, S. Ishimoto, J. Nový, H. Schmieden, I.A. Savin, H. Fischer, A. Antoshkin, M. Slunečka, J.M. Friedrich, J. Smolik, O.M. Kouznetsov, J. Berenguer Antequera, O. Subrt, S. Huber, A. Vidon, B. Marianski, Kamil Augsten, Bakur Parsamyan, J. Pretz, Valery E. Lyubovitskij, E. Zemlyanichkina, S. Platchkov, P. Zavada, R.P. Kurjata, M. Jandek, A. Maggiora, Maria Liz Crespo, K. Lavickova, R. Longo, S. Levorato, Frank Klein, Markus Ball, S.A. Mamon, S. V. Donskov, M. Pešek, V. Jary, A.S. Nunes, A. Koval, B. Ventura, B. Grube, Y.-S. Lian, S. Sarkar, J. Pochodzalla, D. Panzieri, Janusz Marzec, M. Chiosso, Alessandro Bressan, D. von Harrach, F. Kaspar, W. Meyer, K. Kurek, T. Rudnicki, P.M.M. Correia, I. Konorov, Aram Kotzinian, A. Magnon, Jen-Chieh Peng, B.I. Vasilishin, P. Jörg, V.E. Burtsev, F. Gautheron, N. Mitrofanov, Z. Kral, S.S. Dasgupta, A. Nagaytsev, F. Balestra, N. Pierre, Naomi C R Makins, S. Gerassimov, C. Riedl, M. Büchele, A. Vauth, M. Finger, N. Horikawa, J.H. Koivuniemi, T. Iwata, M. Gorzellik, M. Ziembicki, M. Pešková, M. Virius, S. Tessaro, G.V. Khaustov, P.D. Eversheim, H. Suzuki, C.D.R. Azevedo, M. Wagner, H. Pekeler, F. Krinner, Yu.A. Khokhlov, J. Barth, Gerhard K. Mallot, R. Joosten, S. Dasgupta, V. Andrieux, S.-U. Chung, Y. Bedfer, E. Mitrofanov, François Herrmann, P.-J. Lin, Jan Matousek, G. Reicherz, Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, and COMPASS

Subjects
Proton, Isoscalar, Hadron, 0 [higher-order], Deep-inelastic scattering, target: isoscalar, 01 natural sciences, COMPASS, deep inelastic scattering [muon+ nucleon], High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], anti-p: multiplicity, Invariant mass, isoscalar [target], Nuclear Experiment (nucl-ex), Nuclear Experiment, Hadron multiplicities, Quantum chromodynamics, Physics, multiplicity [K+], quark: fragmentation function, higher-order: 0, K+: multiplicity, photon, perturbation theory: higher-order, higher-order: 1, multiplicity [anti-p], lcsh:QC1-999, Bjorken [scaling], beam [muon], factorization [cross section], 1 [higher-order], Particle Physics - Experiment, perturbation theory [quantum chromodynamics], Nuclear and High Energy Physics, FOS: Physical sciences, ratio [multiplicity], pQCD, fragmentation function [quark], scaling: Bjorken, x-dependence, Nuclear physics, phase space, 0103 physical sciences, ddc:530, quantum chromodynamics: perturbation theory, 010306 general physics, muon+ nucleon: deep inelastic scattering, p: multiplicity, Muon, multiplicity [K-], multiplicity: ratio, 010308 nuclear & particles physics, hep-ex, muon: beam, cross section: factorization, CERN SPS, Deep inelastic scattering, multiplicity: measured [charged particle], higher-order [perturbation theory], K-: multiplicity, Antiproton, High Energy Physics::Experiment, lcsh:Physics, charged particle: multiplicity: measured, hadronization, multiplicity [p], experimental results
Abstract

The $\bar{\rm p} $ over p multiplicity ratio is measured in deep-inelastic scattering for the first time using (anti-) protons carrying a large fraction of the virtual-photon energy, $z>0.5$. The data were obtained by the COMPASS Collaboration using a 160 GeV muon beam impinging on an isoscalar $^6$LiD target. The regime of deep-inelastic scattering is ensured by requiring $Q^2$ > 1 (GeV/$c$)$^2$ for the photon virtuality and $W > 5$ GeV/$c^2$ for the invariant mass of the produced hadronic system. The range in Bjorken-$x$ is restricted to $0.01 < x < 0.40$. Protons and antiprotons are identified in the momentum range $20 ��60$ GeV/$c$. In the whole studied $z$-region, the $\bar{\rm p}$ over p multiplicity ratio is found to be below the lower limit expected from calculations based on leading-order perturbative Quantum Chromodynamics (pQCD). Extending our earlier analysis of the K$^-$ over K$^+$ multiplicity ratio by including now events with larger virtual-photon energies, this ratio becomes closer to the expectation of next-to-leading order pQCD. The results of both analyses strengthen our earlier conclusion that the phase space available for hadronisation should be taken into account in the pQCD formalism., 19 pages, 7 figures, 3 tables

Published
2020
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22. Dark Matter Search in Missing Energy Events with NA64

Author

V.A. Polyakov, L. Molina Bueno, B. Radics, D. V. Kirpichnikov, A. Feshchenko, Vladimir Frolov, V.E. Burtsev, A. N. Toropin, G. Vasquez Arenas, R.R. Dusaev, V. A. Matveev, Rimsky Alejandro Rojas, B.I. Vasilishin, Dipanwita Banerjee, B. Ketzer, Nikolaos Charitonidis, A. Yu. Trifonov, A.G. Chumakov, A. V. Dermenev, Igor Konorov, P. Ulloa, S. Gerassimov, M. Kirsanov, Petr Volkov, Serguei Kuleshov, G. D. Kekelidze, V. M. Lysan, Paolo Crivelli, S. V. Donskov, V.D. Samoylenko, A. E. Karneyeu, David R. Cooke, V. O. Tikhomirov, N. V. Krasnikov, Sergey Kovalenko, L. Kravchuk, D. A. Tlisov, V. Yu. Volkov, S. N. Gninenko, E. Depero, M. Hösgen, M. Jeckel, V. A. Kramarenko, I. Tlisova, D. Shchukin, A. Gardikiotis, Yu. V. Mikhailov, D. Peshekhonov, V. E. Lyubovitskij, T. Enik, and André Rubbia

Subjects
Particle physics, Photon, Dark matter, Scalar (mathematics), General Physics and Astronomy, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, 7. Clean energy, 01 natural sciences, Computer Science::Digital Libraries, Dark photon, law.invention, Vector boson, High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), High Energy Physics - Phenomenology (hep-ph), law, 0103 physical sciences, Beam dump, 010306 general physics, Particle Physics - Phenomenology, Physics, Missing energy, Large Hadron Collider, hep-ex, hep-ph, ddc, High Energy Physics - Phenomenology, Physics::Accelerator Physics, Particle Physics - Experiment
Abstract

A search for sub-GeV dark matter production mediated by a new vector boson $A'$, called dark photon, is performed by the NA64 experiment in missing energy events from 100 GeV electron interactions in an active beam dump at the CERN SPS. From the analysis of the data collected in the years 2016, 2017, and 2018 with $2.84\times10^{11}$ electrons on target no evidence of such a process has been found. The most stringent constraints on the $A'$ mixing strength with photons and the parameter space for the scalar and fermionic dark matter in the mass range $\lesssim 0.2$ GeV are derived, thus demonstrating the power of the active beam dump approach for the dark matter search., 6 pages, 4 figures, version accepted for publication in Phys. Rev. Lett. arXiv admin note: text overlap with arXiv:1710.00971, arXiv:1610.02988

Published
2019

23. Transverse extension of partons in the proton probed in the sea-quark range by measuring the DVCS cross section

Author

C. Quintans, A. Vidon, N. C. R. Makins, E. Fuchey, M. V. Zavertyaev, Nikolay Anfimov, Mikhail Mikhasenko, K. Zaremba, V.A. Polyakov, Y.-S. Lian, Franco Bradamante, R. Joosten, C. Marchand, Alexandr Selyunin, G. Sbrizzai, Jan Matousek, G. Reicherz, M. Levillain, C.-Y. Hsieh, B. Grube, V. Frolov, A. Amoroso, N. du Fresne von Hohenesche, C. Riedl, Aram Kotzinian, Nour Makke, W. C. Chang, S.A. Mamon, P. Schiavon, Soumen Paul, V. Andrieux, H. Schmieden, J.M. Friedrich, Adam Szabelski, S. V. Donskov, M. Pešek, A. Srnka, Z.V. Kroumchtein, M. Quaresma, S.-U. Chung, S. Huber, I. J. Choi, A.S. Nunes, P.D. Eversheim, W. Duennweber, J. Pochodzalla, R. Akhunzyanov, T. Sawada, J. Novy, D. Panzieri, Janusz Marzec, K. Schoennig, R.P. Kurjata, H. Suzuki, C.D.R. Azevedo, H. Matsuda, Ilya Kuznetsov, S. Platchkov, M. Faessler, M. Stolarski, François Herrmann, D.V. Peshekhonov, B.I. Vasilishin, M. Virius, T. Grussenmeyer, F. Tessarotto, E. Zemlyanichkina, P. Bordalo, A. Nagaytsev, F. Balestra, N. Pierre, Andres Cicuttin, A. Moretti, R.R. Dusaev, F. Nerling, V. Tskhay, M. Chiosso, G. Hamar, Frank Klein, M. Kraemer, J. ter Wolbeek, Jan Tomsa, G. D. Alexeev, I.A. Savin, W. Meyer, A.V. Efremov, I. Orlov, V.D. Samoylenko, D.I. Ryabchikov, M. Slunecka, Yu. Kisselev, F. Gautheron, Miroslav Sulc, Markus Ball, Yu. Ivanshin, R. Salac, I. Gnesi, F. Tosello, K. Kurek, M. Ziembicki, M. Ostrick, O.P. Gavrichtchouk, W.-D. Nowak, Martin Bodlak, L. Sinha, M. Buechele, L. Dhara, T. Matsuda, E.R. Bielert, B. Badelek, N. I. Zhuravlev, Norihiro Doshita, M. Meyer, A.G. Chumakov, E. Burtin, A. Maggiora, E.A. Levchenko, B. Ketzer, N. d'Hose, G.V. Meshcheryakov, A. Austregesilo, J. Barth, V.F. Konstantinov, S. Dalla Torre, G.V. Khaustov, A. Rychter, Yu. V. Mikhailov, S. Wallner, R. Longo, V.N. Kolosov, S. Sirtl, J.F.C.A. Veloso, J. Smolik, A. Vauth, O. Subrt, P. Zavada, S. Ishimoto, H. Fischer, Gerhard K. Mallot, J. Pretz, Alan D. Martin, M.G. Alexeev, S. Uhl, A.G. Olshevsky, R. Heitz, A. Grasso, Maria Liz Crespo, Y. Miyachi, A.A. Lednev, O.M. Kouznetsov, J. Giarra, Michal Dziewiecki, M. Grosse Perdekamp, C. Franco, D. Neyret, W. Augustyniak, S. Ramos, M. Gorzellik, V. Jary, F. Pereira, O.Yu. Denisov, S. Gerassimov, N. Horikawa, A. Sandacz, Andrew Ivanov, Arseniy Rybnikov, S. Sarkar, Z. Kral, F. Kunne, T. Szameitat, K. Juraskova, S. Tessaro, D. Hahne, P. Sznajder, N.S. Rogacheva, D. von Harrach, C. Regali, F. Krinner, Yu.A. Khokhlov, B. Marianski, Bakur Parsamyan, D. Steffen, P. Joerg, S. Levorato, R. Beck, A. Kerbizi, V.E. Burtsev, N. Mitrofanov, A. Thiel, M. Tasevsky, E. Mitrofanov, G. Pesaro, A. Gridin, E. Seder, Celso Augusto Guimarães Santos, J. Lichtenstadt, Valery E. Lyubovitskij, M. Finger, R. Birsa, Andrea Ferrero, S. Dasgupta, A. Antoshkin, K. Kondo, Kamil Augsten, Y. Bedfer, C. Chatterjee, V. Anosov, J.H. Koivuniemi, M. Pešková, Jen-Chieh Peng, S.S. Dasgupta, A. Kveton, G. Nukazuka, A. Magnon, I. Konorov, Laura Silva, Yakov Petrovich Kulinich, E. M. Kabuss, Takahiro Iwata, B.M. Veit, K. Bicker, Johannes Bernhard, Ch. Dreisbach, A. Guskov, Andrea Bressan, M. Wilfert, Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, COMPASS, Akhunzyanov, R., Alexeev, M. G., Alexeev, G. D., Amoroso, A., Andrieux, V., Anfimov, N. V., Anosov, V., Antoshkin, A., Augsten, K., Augustyniak, W., Austregesilo, A., Azevedo, C. D. R., Badelek, B., Balestra, F., Ball, M., Barth, J., Beck, R., Bedfer, Y., Bernhard, J., Bicker, K., Bielert, E. R., Birsa, R., Bodlak, M., Bordalo, P., Bradamante, F., Bressan, A., Buchele, M., Burtin, E., Burtsev, V. E., Chang, W. -C., Chatterjee, C., Chiosso, M., Choi, I., Chumakov, A. G., Chung, S. -U., Cicuttin, A., Crespo, M. L., Dalla Torre, S., Dasgupta, S. S., Dasgupta, S., Denisov, O. Y., Dhara, L., Donskov, S. V., Doshita, N., Dreisbach, C., Dunnweber, W., Dusaev, R. R., Dziewiecki, M., Efremov, A., Eversheim, P. D., Faessler, M., Ferrero, A., Finger, M., Fischer, H., Franco, C., du Fresne von Hohenesche, N., Friedrich, J. M., Frolov, V., Fuchey, E., Gautheron, F., Gavrichtchouk, O. P., Gerassimov, S., Giarra, J., Gnesi, I., Gorzellik, M., Grasso, A., Gridin, A., Grosse Perdekamp, M., Grube, B., Grussenmeyer, T., Guskov, A., Hahne, D., Hamar, G., von Harrach, D., Heitz, R., Herrmann, F., Horikawa, N., D'Hose, N., Hsieh, C. -Y., Huber, S., Ishimoto, S., Ivanov, A., Ivanshin, Y., Iwata, T., Jary, V., Joosten, R., Jorg, P., Juraskova, K., Kabuss, E., Kerbizi, A., Ketzer, B., Khaustov, G. V., Khokhlov, Y. A., Kisselev, Y., Klein, F., Koivuniemi, J. H., Kolosov, V. N., Kondo, K., Konorov, I., Konstantinov, V. F., Kotzinian, A. M., Kouznetsov, O. M., Kral, Z., Kramer, M., Krinner, F., Kroumchtein, Z. V., Kulinich, Y., Kunne, F., Kurek, K., Kurjata, R. P., Kuznetsov, I. I., Kveton, A., Lednev, A. A., Levchenko, E. A., Levillain, M., Levorato, S., Lian, Y. -S., Lichtenstadt, J., Longo, R., Lyubovitskij, V. E., Maggiora, A., Magnon, A., Makins, N., Makke, N., Mallot, G. K., Mamon, S. A., Marianski, B., Martin, A., Marzec, J., Matousek, J., Matsuda, H., Matsuda, T., Meshcheryakov, G. V., Meyer, M., Meyer, W., Mikhailov, Y. V., Mikhasenko, M., Mitrofanov, E., Mitrofanov, N., Miyachi, Y., Moretti, A., Nagaytsev, A., Nerling, F., Neyret, D., Novy, J., Nowak, W. -D., Nukazuka, G., Nunes, A. S., Olshevsky, A. G., Orlov, I., Ostrick, M., Panzieri, D., Parsamyan, B., Paul, S., Peng, J. -C., Pereira, F., Pesek, M., Peskova, M., Peshekhonov, D. V., Pierre, N., Platchkov, S., Pochodzalla, J., Polyakov, V. A., Pretz, J., Quaresma, M., Quintans, C., Ramos, S., Regali, C., Reicherz, G., Riedl, C., Rogacheva, N. S., Ryabchikov, D. I., Rybnikov, A., Rychter, A., Salac, R., Samoylenko, V. D., Sandacz, A., Santos, C., Sarkar, S., Savin, I. A., Sawada, T., Sbrizzai, G., Schiavon, P., Schmieden, H., Schonning, K., Seder, E., Selyunin, A., Silva, L., Sinha, L., Sirtl, S., Slunecka, M., Smolik, J., Srnka, A., Steffen, D., Stolarski, M., Subrt, O., Sulc, M., Suzuki, H., Szabelski, A., Szameitat, T., Sznajder, P., Tasevsky, M., Tessaro, S., Tessarotto, F., Thiel, A., Tomsa, J., Tosello, F., Tskhay, V., Uhl, S., Vasilishin, B. I., Vauth, A., Veit, B. M., Veloso, J., Vidon, A., Virius, M., Wallner, S., Wilfert, M., ter Wolbeek, J., Zaremba, K., Zavada, P., Zavertyaev, M., Zemlyanichkina, E., Zhuravlev, N., and Ziembicki, M.

Subjects
Photon, generalized parton distribution, muon: polarization, Proton, Generalized Parton Distribution, Parton, measured [cross section], Proton size, nucl-ex, momentum transfer dependence, 01 natural sciences, COMPASS, Subatomär fysik, p: size, Subatomic Physics, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], Nuclear Experiment, Monte Carlo, Quantum chromodynamics, Physics, Range (particle radiation), photon: production, Generalized Parton Distributions, Deep inelastic scattering, Deeply virtual Compton scattering, Exclusive reactions, Exclusive reaction, lcsh:QC1-999, transverse, beam [muon], slope, size: (transverse), Particle Physics - Experiment, Quark, Nuclear and High Energy Physics, exclusive reaction, slope: (calculated), liquid: target [hydrogen], photon: mediation, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear physics, hydrogen: liquid: target, 0103 physical sciences, ddc:530, Nuclear Physics - Experiment, 010306 general physics, beam: polarization, hep-ex, 010308 nuclear & particles physics, muon: beam, 160 GeV/c, +muon+p+photon%22">muon p --> muon p photon, size [p], Compton scattering, cross section: measured, CERN SPS, [PHYS.HPHE]Physics [physics]/High Energy Physics - Phenomenology [hep-ph], High Energy Physics::Experiment, lcsh:Physics, experimental results
Abstract

Physics letters / B B793, 188-194 (2019). doi:10.1016/j.physletb.2019.04.038, Published by North-Holland Publ., Amsterdam

Published
2019
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24. Performance of Multiplexed XY Resistive Micromegas detectors in a high intensity beam

Author

B. Radics, Adrian Fabich, G. Vasquez Arenas, D. A. Tlisov, V.A. Polyakov, E. Depero, Vladimir Peshekhonov, V. V. Myalkovskiy, A.G. Chumakov, S. V. Donskov, Igor Konorov, Paolo Crivelli, A. V. Dermenev, A. E. Karneyeu, André Rubbia, M. Kirsanov, A. N. Toropin, D. Peshekhonov, V.D. Samoylenko, R.R. Dusaev, M. Hösgen, V. A. Kramarenko, B. Ketzer, Yu. V. Mikhailov, Vladimir Frolov, David R. Cooke, D. Banerjee, V. A. Matveev, P. Ulloa, S. N. Gninenko, Serguei Kuleshov, S. Mamon, B.I. Vasilishin, A. Gardikiotis, V.E. Burtsev, Filipp Dubinin, V. O. Tikhomirov, V. M. Lysan, S. Emmenegger, V. E. Lyubovitskij, and Evgenii Levchenko

Subjects
Nuclear and High Energy Physics, Physics - Instrumentation and Detectors, Physics::Instrumentation and Detectors, FOS: Physical sciences, STRIPS, Micromegas, Multiplexing, Tracking, Gas detectors, Charged particles detector, Position sensitive detector, Tracking (particle physics), 01 natural sciences, High Energy Physics - Experiment, law.invention, High Energy Physics - Experiment (hep-ex), Optics, law, 0103 physical sciences, Detectors and Experimental Techniques, 010306 general physics, Instrumentation, Image resolution, physics.ins-det, Physics, Resistive touchscreen, Large Hadron Collider, 010308 nuclear & particles physics, business.industry, hep-ex, Detector, MicroMegas detector, Instrumentation and Detectors (physics.ins-det), ddc, business, Beam (structure), Particle Physics - Experiment
Abstract

We present the performance of multiplexed XY resistive Micromegas detectors tested in the CERN SPS 100 GeV/c electron beam at intensities up to 3.3 × 10 5e−/(s-cm2). So far, all studies with multiplexed Micromegas have only been reported for tests with radioactive sources and cosmic rays. The use of multiplexed modules in high intensity environments was not explored due to the effect of ambiguities in the reconstruction of the hit point caused by the multiplexing feature. For the specific mapping and beam intensities analyzed in this work with a multiplexing factor of five, more than 50% level of ambiguity is introduced due to particle pile-up as well as fake clusters due to the mapping feature. Our results prove that by using the additional information of cluster size and integrated charge from the signal clusters induced on the XY strips, the ambiguities can be reduced to a level below 2%. The tested detectors are used in the CERN NA64 experiment for tracking the incoming particles bending in a magnetic field in order to reconstruct their momentum. The average hit detection efficiency of each module was found to be 96% at the highest beam intensities. By using four modules a tracking resolution of 1.1% was obtained with 85% combined tracking efficiency., Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 881, ISSN:0168-9002, ISSN:1872-9576

Published
2018

25. High purity 100 GeV electron identification with synchrotron radiation

Author

V. V. Myalkovskiy, B. Radics, Adrian Fabich, B. Ketzer, B.I. Vasilishin, Danila Tlisov, A.G. Chumakov, Igor Konorov, V.D. Samoylenko, David R. Cooke, S. V. Donskov, A. Gardikiotis, P. Ulloa, Viktor Matveev, S. N. Gninenko, Mikhail Kirsanov, André Rubbia, M. Hösgen, Yu. V. Mikhailov, V.A. Polyakov, D.V. Peshekhonov, Anton Karneyeu, R.R. Dusaev, G. Vasquez Arenas, Paolo Crivelli, D. Banerjee, Filipp Dubinin, V. M. Lysan, V. O. Tikhomirov, S. Emmenegger, Sergey Kuleshov, Viktor Kramarenko, Valery E. Lyubovitskij, Vladimir Frolov, Alexander Dermenev, V.E. Burtsev, E. Depero, Vladimir Peshekhonov, and Alexander Toropin

Subjects
Nuclear and High Energy Physics, Physics - Instrumentation and Detectors, Synchrotron radiation, FOS: Physical sciences, Electron, 01 natural sciences, law.invention, High Energy Physics - Experiment, Nuclear physics, Synchrotron detector, Hadron rejection, High energy electron tagging, High Energy Physics - Experiment (hep-ex), Dipole magnet, law, 0103 physical sciences, Beam dump, Detectors and Experimental Techniques, 010306 general physics, Nuclear Experiment, Instrumentation, physics.ins-det, Physics, Large Hadron Collider, 010308 nuclear & particles physics, hep-ex, Instrumentation and Detectors (physics.ins-det), Charged particle, Beamline, Physics::Accelerator Physics, High Energy Physics::Experiment, Beam (structure), Particle Physics - Experiment
Abstract

In high energy experiments such as active beam dump searches for rare decays and missing energy events, the beam purity is a crucial parameter. In this paper we present a technique to reject heavy charged particle contamination in the 100 GeV electron beam of the H4 beam line at CERN SPS. The method is based on the detection with BGO scintillators of the synchrotron radiation emitted by the electrons passing through a bending dipole magnet. A 100 GeV $\pi^-$ beam is used to test the method in the NA64 experiment resulting in a suppression factor of $10^{-5}$ while the efficiency for electron detection is $\sim$95%. The spectra and the rejection factors are in very good agreement with the Monte Carlo simulation. The reported suppression factors are significantly better than previously achieved., Comment: 10 pages, 6 figures

Published
2017

26. Search for Axionlike and Scalar Particles with the NA64 Experiment

Author

B.I. Vasilishin, V.D. Samoylenko, David R. Cooke, P. Ulloa, V.E. Burtsev, Serguei Kuleshov, L. Molina Bueno, L. Kravchuk, Dipanwita Banerjee, V. A. Matveev, V. Yu. Volkov, D. A. Tlisov, Petr Volkov, Rimsky Alejandro Rojas, D. Shchukin, André Rubbia, E. Depero, M. Kirsanov, Vassili Kachanov, S. N. Gninenko, M. Jeckel, N. V. Krasnikov, V. E. Lyubovitskij, Paolo Crivelli, A. V. Dermenev, V. A. Kramarenko, V. M. Lysan, V. O. Tikhomirov, A.G. Chumakov, V.A. Polyakov, Nikolaos Charitonidis, A. Yu. Trifonov, Igor Konorov, D. V. Kirpichnikov, T. Enik, A. N. Toropin, B. Ketzer, A. Feshchenko, Vladimir Frolov, R.R. Dusaev, V.N. Kolosov, A. Gardikiotis, S. G. Kovalenko, H. Sieber, G. D. Kekelidze, I. Tlisova, G. Vasquez Arenas, Yu. V. Mikhailov, S. V. Donskov, A. E. Karneyeu, B. Radics, Johannes Bernhard, M. Hösgen, D. Peshekhonov, and S. Gerassimov

Subjects
electron beam, Particle physics, Photon, Physics::Instrumentation and Detectors, Gammagamma, General Physics and Astronomy, Virtual particle, FOS: Physical sciences, Electron, Model independent, Computer Science::Digital Libraries, 01 natural sciences, Virtual photons, High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), Parameter spaces, High Energy Physics - Phenomenology (hep-ph), Germanium compounds, brems radiation, 0103 physical sciences, 010306 general physics, Axion, Primakoff effect, Particle Physics - Phenomenology, Physics, Missing energy, Two photon, hep-ex, Bremsstrahlung, hep-ph, Coupling strengths, Pseudoscalar, High Energy Physics - Phenomenology, axion, Particle Physics - Experiment
Abstract

We carried out a model-independent search for light scalar (s) and pseudoscalar axionlike (a) particles that couple to two photons by using the high-energy CERN SPS H4 electron beam. The new particles, if they exist, could be produced through the Primakoff effect in interactions of hard bremsstrahlung photons generated by 100 GeV electrons in the NA64 active dump with virtual photons provided by the nuclei of the dump. The a(s) would penetrate the downstream HCAL module, serving as shielding, and would be observed either through their $a(s)\to\gamma \gamma$ decay in the rest of the HCAL detector or as events with large missing energy if the a(s) decays downstream of the HCAL. This method allows for the probing the a(s) parameter space, including those from generic axion models, inaccessible to previous experiments. No evidence of such processes has been found from the analysis of the data corresponding to $2.84\times10^{11}$ electrons on target allowing to set new limits on the $a(s)\gamma\gamma$-coupling strength for a(s) masses below 55 MeV., Comment: This publication is dedicated to the memory of our colleague Danila Tlisov. 7 pages, 5 figures, revised version accepted for publication in Phys. Rev. Lett

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