Production of the charmonium states χc1 and χc2 in proton nucleus interactions at s=41.6 GeV
Year: 2009
Type: article
Abstract: A measurement of the ratio ${R}_{{\ensuremath{\chi}}_{c}}=({\ensuremath{\chi}}_{c}\ensuremath{\rightarrow}J/\ensuremath{\psi}+\ensuremath{\gamma})/J/\ensuremath{\psi}$ in $p\mathrm{C}$, $p\mathrm{Ti}$, and $p\mathrm{W}$ interactions at $920\text{ }\text{ }\mathrm{GeV}/c$ ($\sqrt{s}=41.6\text{ }\text{ }\mathrm{GeV}$) in the Feynman-x range $\ensuremath{-}0.35<{x}_{F}^{J/\ensuremath{\psi}}<0.15$ is presented. Both ${\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ and ${e}^{+}{e}^{\ensuremath{-}}$ $J/\ensuremath{\psi}$ decay channels are observed with an overall statistics of about 15 000 ${\ensuremath{\chi}}_{c}$ events, which is by far the largest available sample in pA collisions. The result is ${R}_{{\ensuremath{\chi}}_{c}}=0.188\ifmmode\pm\else\textpm\fi{}{0.013}_{\mathrm{st}}{\genfrac{}{}{0}{}{+0.024}{\ensuremath{-}0.022}}_{\mathrm{sys}}$ averaged over the different materials, when no $J/\ensuremath{\psi}$ and ${\ensuremath{\chi}}_{c}$ polarizations are considered. The ${\ensuremath{\chi}}_{c1}$ to ${\ensuremath{\chi}}_{c2}$ production ratio ${R}_{12}={R}_{{\ensuremath{\chi}}_{c}1}/{R}_{{\ensuremath{\chi}}_{c}2}$ is measured to be $1.02\ifmmode\pm\else\textpm\fi{}0.40$, leading to a cross section ratio $\frac{\ensuremath{\sigma}({\ensuremath{\chi}}_{c1})}{\ensuremath{\sigma}({\ensuremath{\chi}}_{c2})}=0.57\ifmmode\pm\else\textpm\fi{}0.23$. The dependence of ${R}_{{\ensuremath{\chi}}_{c}}$ on the Feynman-x of the $J/\ensuremath{\psi}$, ${x}_{F}^{J/\ensuremath{\psi}}$, and its transverse momentum, ${p}_{T}^{J/\ensuremath{\psi}}$, is studied, as well as its dependence on the atomic number, A, of the target. For the first time, an extensive study of possible biases on ${R}_{{\ensuremath{\chi}}_{c}}$ and ${R}_{12}$ due to the dependence of acceptance on the polarization states of $J/\ensuremath{\psi}$ and ${\ensuremath{\chi}}_{c}$ is performed. By varying the polarization parameter, ${\ensuremath{\lambda}}_{\mathrm{obs}}$, of all produced $J/\ensuremath{\psi}$'s by two sigma around the value measured by HERA-B, and considering the maximum variation due to the possible ${\ensuremath{\chi}}_{c1}$ and ${\ensuremath{\chi}}_{c2}$ polarizations, it is shown that ${R}_{{\ensuremath{\chi}}_{c}}$ could change by a factor between 1.02 and 1.21 and ${R}_{12}$ by a factor between 0.89 and 1.16.
Authors: I. Abt, M. Adams, M. Agari, H. Albrecht, A. Aleksandrov, V. Amaral, A. Amorim, S. J. Aplin, V. Aushev, Y. Bagaturia, V. Balagura, M. Bargiotti, O. Barsukova, J. Bastos, J. Batista, C. Bauer, Th. S. Bauer, A. Belkov, Ar. Belkov, I. Belotelov, A. Bertin, B. Bobchenko, M. Böcker, A. Bogatyrev, G. Bohm, M. Bräuer, M. Bruinsma, M. Bruschi, P. Buchholz, T. Buran, J. Carvalho, P. Conde, C. Cruse, M. Dam, K. M. Danielsen, M. Danilov, S. De Castro, H. Deppe, X. Dong, H. B. Dreis, V. Egorytchev, K. Ehret, F. Eisele, D. Emeliyanov, S. Essenov, L. Fabbri, P. Faccioli, M. Feuerstack-Raible, J. Flammer, B. Fominykh, M. Funcke, Ll. Garrido, A. Gellrich, B. Giacobbe, J. Gläß, D. Goloubkov, Y. Golubkov, A. Golutvin, I. Golutvin, I. Gorbounov, A. Gorišek, O. Gouchtchine, D. C. Goulart, S. Gradl, W. Gradl, F. Grimaldi, J. Groth-Jensen, Yu. Guilitsky, J. D. Hansen, J. M. Hernández, W. Hofmann, M. Hohlmann, T. Hott, W. Hulsbergen, U. Husemann, O. Igonkina, M. Ispiryan, T. Jagla, C. Jiang, H. Kapitza, S. Karabekyan, N. Karpenko, S. Keller, J. Kessler, F. Khasanov, Yu. Kiryushin, I. Kisel, E. Klinkby, K. T. Knöpfle, H. Kolanoski, S. Korpar, C. Krauss, P. Kreuzer, P. Križan, D. Krücker, S. Kupper, T. Kvaratskheliia, A. Lanyov, K. Lau, B. Lewendel, T. Lohse, B. Lomonosov, R. Männer, R. Mankel, S. Masciocchi, I. Massa, I. Matchikhilian, G. Medin, M. Medinnis, M. Mevius, A. Michetti, Yu. Mikhailov, R. Mizuk, R. Muresan, M. zur Nedden, M. Negodaev, M. Nörenberg, S. Nowak, M. T. Núñez Pardo de Vera, M. Ouchrif, F. Ould-Saada, C. Padilla, D. Peralta, R. Pernack, R. Pestotnik, B. AA. Petersen, M. Piccinini, M. A. Pleier, M. Poli, V. Popov, D. Pose, S. Prystupa, V. Pugatch, Y. Pylypchenko, J. Pyrlik, K. Reeves, D. Reßing, H. Rick, I. Riu, P. Robmann, I. Rostovtseva, V. Rybnikov, F. Sánchez, A. Sbrizzi, M. Schmelling, B. Schmidt, A. Schreiner, H. Schröder, U. Schwanke, A. J. Schwartz, A. S. Schwarz, B. Schwenninger, B. Schwingenheuer, F. Sciacca, N. Semprini-Cesari, S. Shuvalov, L. Silva, L. Sözüer, S. Solunin, A. Somov, S. Somov, J. Spengler, R. Spighi, A. Spiridonov, A. Stanovnik, M. Starič, C. Stegmann, H. S. Subramania, M. Symalla, I. Tikhomirov, M. Titov, I. Tsakov, U. Uwer, C. van Eldik, Yu. Vassiliev, M. Villa, A. Vitale, I. Vukotic, H. Wahlberg, A. H. Walenta, M. Walter, J. J. Wang, D. Wegener, U. Werthenbach, H. Wolters, R. Wurth, A. Wurz, S. Xella-Hansen, Yu. Zaitsev, M. Zavertyaev, T. Zeuner, A. Zhelezov, Z. Zheng, R. Zimmermann, T. Živko, A. Zoccoli
Institutions: Citigroup, Max Planck Institute for Physics, TU Dortmund University, Max Planck Society, Max Planck Institute for Nuclear Physics, Deutsches Elektronen-Synchrotron DESY, Institute for Nuclear Research, Institute for Theoretical and Experimental Physics, Istituto Nazionale di Fisica Nucleare, Sezione di Bologna, University of Bologna, Joint Institute for Nuclear Research, National Institute for Subatomic Physics, University of Siegen, Utrecht University, University of Oslo, Universitat de Barcelona, University of Copenhagen, Heidelberg University, Institute of High Energy Physics, University of Mannheim, Lomonosov Moscow State University, Jožef Stefan Institute, University of Cincinnati, Institute for High Energy Physics, University of Houston, University of Rostock, Humboldt-Universität zu Berlin, University of Maribor, University of California, Los Angeles, University of Ljubljana, P.N. Lebedev Physical Institute of the Russian Academy of Sciences, Istituto Nazionale di Fisica Nucleare, University of Zurich, Bulgarian Academy of Sciences, Institute for Nuclear Research and Nuclear Energy, Tsinghua University
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
Funders: National Science Foundation, U.S. Department of Energy, Strong, Deutsche Forschungsgemeinschaft, Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung, Bundesministerium für Bildung und Forschung, Norges Forskningsråd, Ministrstvo za Izobraževanje, Znanost in Šport, Ministry of Education and Science of Ukraine, Deutsches Elektronen-Synchrotron
OpenAlex ID: W2103259199