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Your search keyword '"B. I. Vasilishin"' showing total 11 results
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11 results on '"B. I. Vasilishin"'

1. Probing the explanation of the muon (g-2) anomaly and thermal light dark matter with the semi-visible dark photon channel

Author

C. Cazzaniga, P. Odagiu, E. Depero, L. Molina Bueno, Yu. M. Andreev, D. Banerjee, J. Bernhard, V. E. Burtsev, N. Charitonidis, A. G. Chumakov, D. Cooke, P. Crivelli, A. V. Dermenev, S. V. Donskov, R. R. Dusaev, T. Enik, A. Feshchenko, V. N. Frolov, A. Gardikiotis, S. G. Gerassimov, S. Girod, S. N. Gninenko, M. Hösgen, V. A. Kachanov, A. E. Karneyeu, G. Kekelidze, B. Ketzer, D. V. Kirpichnikov, M. M. Kirsanov, V. N. Kolosov, I. V. Konorov, S. G. Kovalenko, V. A. Kramarenko, L. V. Kravchuk, N. V. Krasnikov, S. V. Kuleshov, V. E. Lyubovitskij, V. Lysan, V. A. Matveev, Yu. V. Mikhailov, D. V. Peshekhonov, V. A. Polyakov, B. Radics, R. Rojas, A. Rubbia, V. D. Samoylenko, D. Shchukin, H. Sieber, V. O. Tikhomirov, I. V. Tlisova, D. A. Tlisov, A. N. Toropin, A. Yu. Trifonov, B. I. Vasilishin, G. Vasquez Arenas, P. V. Volkov, V. Yu. Volkov, P. Ulloa, and NA64 Collaboration

Subjects
Astrophysics, QB460-466, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract

Abstract We report the results of a search for a new vector boson ( $$ A'$$ A ′ ) decaying into two dark matter particles $$\chi _1 \chi _2$$ χ 1 χ 2 of different mass. The heavier $$\chi _2$$ χ 2 particle subsequently decays to $$\chi _1$$ χ 1 and an off-shell Dark Photon $$ A'^* \rightarrow e^+e^-$$ A ′ ∗ → e + e - . For a sufficiently large mass splitting, this model can explain in terms of new physics the recently confirmed discrepancy observed in the muon anomalous magnetic moment at Fermilab. Remarkably, it also predicts the observed yield of thermal dark matter relic abundance. A detailed Monte-Carlo simulation was used to determine the signal yield and detection efficiency for this channel in the NA64 setup. The results were obtained re-analyzing the previous NA64 searches for an invisible decay $$A'\rightarrow \chi \overline{\chi }$$ A ′ → χ χ ¯ and axion-like or pseudo-scalar particles $$a \rightarrow \gamma \gamma $$ a → γ γ . With this method, we exclude a significant portion of the parameter space justifying the muon g-2 anomaly and being compatible with the observed dark matter relic density for $$A'$$ A ′ masses from 2 $$m_e$$ m e up to 390 MeV and mixing parameter $$\varepsilon $$ ε between $$3\times 10^{-5}$$ 3 × 10 - 5 and $$2\times 10^{-2}$$ 2 × 10 - 2 .

Published
2021
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2. Spin density matrix elements in exclusive $$\omega $$ ω meson muoproduction

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, 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, A. Ferrero, M. Finger, 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, P. Jörg, R. Joosten, 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, M. Pešek, D. V. Peshekhonov, M. Pešková, N. Pierre, S. Platchkov, J. Pochodzalla, V. A. Polyakov, J. Pretz, M. Quaresma, C. Quintans, C. Regali, 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, T. Szameitat, 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, M. Ziembicki, and COMPASS Collaboration

Subjects
Astrophysics, QB460-466, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract

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

Published
2021
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3. Hunting down the X17 boson at the CERN SPS

Author

NA64 Collaboration, E. Depero, Yu. M. Andreev, D. Banerjee, J. Bernhard, V. E. Burtsev, N. Charitonidis, A. G. Chumakov, D. Cooke, P. Crivelli, A. V. Dermenev, S. V. Donskov, R. R. Dusaev, T. Enik, A. Feshchenko, V. N. Frolov, A. Gardikiotis, S. G. Gerassimov, S. Girod, S. N. Gninenko, M. Hösgen, V. A. Kachanov, A. E. Karneyeu, G. Kekelidze, B. Ketzer, D. V. Kirpichnikov, M. M. Kirsanov, V. N. Kolosov, I. V. Konorov, S. G. Kovalenko, V. A. Kramarenko, L. V. Kravchuk, N. V. Krasnikov, S. V. Kuleshov, V. E. Lyubovitskij, V. Lysan, V. A. Matveev, Yu. V. Mikhailov, L. Molina Bueno, D. V. Peshekhonov, V. A. Polyakov, B. Radics, R. Rojas, A. Rubbia, V. D. Samoylenko, D. Shchukin, H. Sieber, V. O. Tikhomirov, vI. Tlisova, D. A. Tlisov, A. N. Toropin, A. Yu. Trifonov, B. I. Vasilishin, G. Vasquez Arenas, P. V. Volkov, V. Yu. Volkov, and P. Ulloa

Subjects
Astrophysics, QB460-466, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract

Abstract Recently, the ATOMKI experiment has reported new evidence for the excess of $$e^+e^-$$ e + e - events with a mass $$\sim $$ ∼ 17 MeV in the nuclear transitions of $$^4$$ 4 He, that they previously observed in measurements with $$^8$$ 8 Be. These observations could be explained by the existence of a new vector $$X17$$ X 17 boson. So far, the search for the decay $$X17 \rightarrow e^+ e^-$$ X 17 → 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 $$X17$$ X 17 parameter space. If a signal-like event is detected, an unambiguous observation is achieved by reconstructing the invariant mass of the $$X17$$ X 17 decay with the proposed method. To reach this goal an optimization of the $$X17$$ X 17 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.

Published
2020
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5. Measurement of the tensor analyzing power component T20 for the incoherent neutral-pion photoproduction on a deuteron

Author

B. I. Vasilishin, A. I. Fix, V. V. Gauzshtein, E. M. Darwish, M. Ya. Kuzin, M. I. Levchuk, A. Yu. Loginov, D. M. Nikolenko, I. A. Rachek, Yu. V. Shestakov, D. K. Toporkov, A. V. Yurchenko, S. A. Zevakov, A. V. Bogomyagkov, A. N. Zhuravlev, S. E. Karnaev, V. A. Kiselev, E. B. Levichev, O. I. Meshkov, S. I. Mishnev, I. N. Okunev, P. A. Piminov, E. A. Simonov, S. V. Sinyatkin, and E. V. Starostina

Published
2022
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6. Search for a New B-L Z^{'} Gauge Boson with the NA64 Experiment at CERN

Author

Yu M, Andreev, D, Banerjee, B, Banto Oberhauser, J, Bernhard, P, Bisio, V E, Burtsev, A, Celentano, N, Charitonidis, A G, Chumakov, D, Cooke, P, Crivelli, E, Depero, A V, Dermenev, S V, Donskov, R R, Dusaev, T, Enik, V N, Frolov, A, Gardikiotis, S G, Gerassimov, S N, Gninenko, M, Hösgen, M, Jeckel, V A, Kachanov, A E, Karneyeu, G, Kekelidze, B, Ketzer, D V, Kirpichnikov, M M, Kirsanov, V N, Kolosov, S G, Kovalenko, V A, Kramarenko, L V, Kravchuk, N V, Krasnikov, S V, Kuleshov, V E, Lyubovitskij, V, Lysan, L, Marsicano, V A, Matveev, Yu V, Mikhailov, L, Molina Bueno, D V, Peshekhonov, V A, Polyakov, B, Radics, A, Rubbia, K M, Samalantin, V D, Samoylenko, H, Sieber, D, Shchukin, O, Soto, V O, Tikhomirov, I V, Tlisova, A N, Toropin, B I, Vasilishin, P V, Volkov, V Yu, Volkov, I, Voronchikhin, and J, Zamora-Saá

Abstract

A search for a new Z^{'} gauge boson associated with (un)broken B-L symmetry in the keV-GeV mass range is carried out for the first time using the missing-energy technique in the NA64 experiment at the CERN SPS. From the analysis of the data with 3.22×10^{11} electrons on target collected during 2016-2021 runs, no signal events were found. This allows us to derive new constraints on the Z^{'}-e coupling strength, which, for the mass range 0.3≲m_{Z^{'}}≲100 MeV, are more stringent compared to those obtained from the neutrino-electron scattering data.

Published
2022

7. Measurement of the tensor analyzing power $$T_{20}$$ for the reaction $$\gamma d \rightarrow d\pi ^0$$

Author

E. V. Starostina, Eed M. Darwish, M. Ya. Kuzin, Yu. V. Shestakov, A. Yu. Loginov, D. M. Nikolenko, S. A. Zevakov, B. I. Vasilishin, R. Sh. Sadykov, A. V. Bogomyagkov, E. A. Simonov, V. A. Kiselev, Oleg Meshkov, M.I. Levchuk, V. V. Gauzshtein, Sergey Karnaev, Evgeny Levichev, Sergey Sinyatkin, Pavel Piminov, S. I. Mishnev, I. N. Okunev, A. N. Zhuravlev, D. K. Toporkov, and I. A. Rachek

Subjects
Physics, Nuclear and High Energy Physics, 010308 nuclear & particles physics, Nuclear Theory, Hadron, Photon energy, 01 natural sciences, Nuclear physics, Pion, Deuterium, 0103 physical sciences, Nuclear fusion, Tensor, Polar coordinate system, Nuclear Experiment, 010306 general physics, Storage ring
Abstract

We present the first accurate results of measurements of the tensor analyzing power component $$T_{20}$$ for the coherent neutral pion photoproduction on the deuteron. The measurements were performed at the Budker Institute of Nuclear Physics at VEPP-3 storage ring using the internal tensor polarized deuterium target. The measurements cover the region of photon energy from 200 to 450 MeV and the region of the center-of-mass pion polar angle from 100 to 140 degrees. The results obtained are compared with predictions of several theoretical models.

Published
2020
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8. Measurement of the tensor analyzing power T20 for the reaction γd → pnπ0

Author

I. A. Rachek, M. Ya. Kuzin, B. I. Vasilishin, A. Fix, Eed M. Darwish, Yu. V. Shestakov, V. V. Gauzshtein, M.I. Levchuk, A. V. Yurchenko, D. M. Nikolenko, D. K. Toporkov, A. Yu. Loginov, S. A. Zevakov, and R. Sh. Sadykov

Subjects
Physics, Nuclear and High Energy Physics, Range (particle radiation), Photon, Nuclear Theory, General Physics and Astronomy, Astronomy and Astrophysics, Photon energy, Power (physics), Nuclear physics, High Energy Physics::Experiment, Tensor, Nuclear Experiment, Nucleon
Abstract

This paper presents new results for the [Formula: see text]-component of the tensor analyzing power of the reaction [Formula: see text] in the photon energy range of [Formula: see text]. The experimental statistics accumulated in 2013 at the VEPP-3 accelerator-storage complex is used. The reaction events are identified by the coincidence registration of the proton and two [Formula: see text]-quanta from the decay of the neutral pion. To determine the [Formula: see text]-component, the asymmetry of the yields with respect to the change of sign of the tensor polarization of the deuterium target is measured. The experimental results are compared with the theoretical calculations in which the MAID 2007 model is used as the elementary pion–nucleon photoproduction amplitude and contributions from the pion–nucleon and nucleon–nucleon rescattering are taken into account.

Published
2021
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9. Experimental Study of the Components of the Tensor Analyzing Power of the Reaction γd → ppπ –

Author

D. M. Nikolenko, M. I. Levchuk, D. K. Toporkov, R. Sh. Sadykov, B. I. Vasilishin, R. R. Dusaev, K. V. Afanas’ev, S. A. Zevakov, I. A. Rachek, V. V. Gauzshtein, A. Yu. Loginov, A. V. Gramolin, and Yu. V. Shestakov

Subjects
Physics, Meson, 010308 nuclear & particles physics, Nuclear Theory, General Physics and Astronomy, Photon energy, 01 natural sciences, Coincidence, Power (physics), Nuclear physics, Electron storage, Deuterium, 0103 physical sciences, Scintillation counter, Physics::Accelerator Physics, Tensor, Nuclear Experiment, 010306 general physics
Abstract

The three components of the tensor analyzing power of the exclusive π– meson photoproduction reaction on deuterons measured simultaneously in the photon energy ranges 300–900 MeV and 50–210 MeV are presented. The experiment made use of an internal tensor-polarized deuterium-gas target of the VEPP-3 electron storage ring and the two-proton coincidence recording method. The results obtained are compared with theoretical predictions.

Published
2016
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10. Measurements of the tensor analyzing power T20 of the reaction γd → dπ0

Author

Yu. V. Shestakov, R. Sh. Sadykov, E. V. Starostina, E. A. Simonov, M.I. Levchuk, A. V. Bogomyagkov, D. M. Nikolenko, Evgeny Levichev, V. V. Gauzshtein, D. K. Toporkov, A. N. Zhuravlev, Sergey Sinyatkin, Pavel Piminov, I. N. Okunev, A. Yu. Loginov, V. A. Tryasuchev, Oleg Meshkov, S. A. Zevakov, S. I. Mishnev, Sergey Karnaev, I. A. Rachek, B. I. Vasilishin, and V. A. Kiselev

Subjects
Physics, Nuclear and High Energy Physics, Photon, 010308 nuclear & particles physics, Nuclear Theory, General Physics and Astronomy, Power component, 01 natural sciences, Power (physics), Nuclear physics, Pion, Deuterium, 0103 physical sciences, Tensor, Nuclear Experiment, 010306 general physics, Nucleon
Abstract

The paper presents the results of measurements of the tensor analyzing power component [Formula: see text] for the coherent neutral pion photoproduction on the deuteron. The measurements were performed in the Budker Institute of Nuclear Physics using the internal tensor polarized deuterium target at VEPP-3 storage ring. The measurements covered the region of the photon energy 240 — 420[Formula: see text]MeV and the region of the center-of-mass pion polar angle 100–140[Formula: see text]. The results of measurements were compared with the calculations performed within frameworks of several theoretical models.

Published
2020
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11. Transverse Extension of Partons in the Proton probed by Deeply Virtual Compton Scattering

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. Badelek, 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. Buechele, 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. Duennweber, 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. Joerg, 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. Kraemer, 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, C. Marchand, B. Marianski, A. Martin, J. Marzec, J. Matousek, 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. Novy, 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. Pesek, M. Peskova, 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. Schoennig, 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, M. Ziembicki, 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), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay

Subjects
slope: (calculated), photon: production, muon: polarization, beam: polarization, 160 GeV/c, +muon+p+photon%22">muon p --> muon p photon, photon: mediation, FOS: Physical sciences, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], CERN SPS, cross section: measured, momentum transfer dependence, COMPASS, High Energy Physics - Experiment, hydrogen: liquid: target, High Energy Physics - Experiment (hep-ex), deeply virtual Compton scattering, [ PHYS.HEXP ] Physics [physics]/High Energy Physics - Experiment [hep-ex], [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], [ PHYS.NEXP ] Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment (nucl-ex), size: (transverse), Nuclear Experiment, Monte Carlo
Abstract

We report on the first measurement of exclusive single-photon muoproduction on the proton by COMPASS using 160 GeV/$c$ polarized $\mu^+$ and $\mu^-$ beams of the CERN SPS impinging on a liquid hydrogen target. We determine the dependence of the average of the measured $\mu^+$ and $\mu^-$ cross sections for deeply virtual Compton scattering on the squared four-momentum transfer $t$ from the initial to the final final proton. The slope $B$ of the $t$-dependence is fitted with a single exponential function, which yields $B=(4.3 \ \pm \ 0.6_{\text{stat}}\_{- \ 0.3}^{+ \ 0.1}\big\rvert_{\text{sys}}) (\text{GeV}/c)^{-2}$. This result can be converted into an average transverse extension of partons in the proton, $\sqrt{\langle r_{\perp}^2 \rangle} = (0.58 \ \pm \ 0.04_{\text{stat}}\_{- \ 0.02}^{+ \ 0.01}\big\rvert_{\text{sys}})\text{fm}$. For this measurement, the average virtuality of the photon mediating the interaction is $\langle Q^2 \rangle = 1.8\,(\text{GeV/}c)^2$ and the average value of the Bjorken variable is $\langle x_{\text{Bj}} \rangle = 0.056$., Comment: 13 pages, 5 figures

Published
2018
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