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Measurement of the cross section for hard exclusive $\pi^0$ muoproduction on the proton

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 (+192 others)
2020

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We report on a measurement of hard exclusive π 0 muoproduction on the proton by COMPASS using 160 GeV/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 < |t| < 0.64 (GeV/c) 2 . The average kinematics of the measurement are Q 2 = 2.0
more » ... /c) 2 , ν = 12.8 GeV, x B j = 0.093 and −t = 0.256 (GeV/c) 2 . Fitting the azimuthal dependence reveals a combined contribution by transversely and longitudinally polarised photons of (8.2 ± 0.9 stat + 1.2 − 1.2 sys ) nb/(GeV/c) 2 , as well as transverse-transverse and longitudinal-transverse interference contributions of (−6.1 ± 1.3 stat + 0.7 − 0.7 sys ) nb/(GeV/c) 2 and (1.5 ± 0.5 stat respectively. Our results provide important input for modelling Generalised Parton Distributions. In the context of the phenomenological Goloskokov-Kroll model, the statistically significant transversetransverse interference contribution constitutes clear experimental evidence for the chiral-odd GPD E T .
doi:10.18154/rwth-2020-07758 fatcat:cnrygiyoevb37c3pqan6logb7u
Citation

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, Michael Finger, 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, M. Ziembicki, COMPASS Collaboration. "Measurement of the cross section for hard exclusive $\pi^0$ muoproduction on the proton." (2020) 135454 (2020). doi:10.1016/j.physletb.2020.135454