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arXiv · 0905.0101

Evidence for $πK$-atoms with DIRAC

B. Adeva·L. Afanasyev·Y. Allkofer·C. Amsler·A. Anania·A. Benelli·V. Brekhovskikh·G. Caragheorgheopol·T. Cechak·M. Chiba·P. Chliapnikov·C. Ciocarlan·S. Constantinescu·C. Curceanu·C. Detraz·D. Dreossi·D. Drijard·A. Dudarev·M. Duma·D. Dumitriu·J. L. Fungueiriño·J. Gerndt·A. Gorin·O. Gorchakov·K. Gritsay·C. Guaraldo·M. Gugiu·M. Hansroul·Z. Hons·S. Horikawa·M. Iliescu·V. Karpukhin·J. Kluson·M. Kobayashi·V. Komarov·V. Kruglov·L. Kruglova·A. Kulikov·A. Kuptsov·I. Kurochkin·A. Lamberto·A. Lanaro·V. Lapshin·R. Lednicky·P. Levi Sandri·A. Lopez Aguera·V. Lucherini·I. Manuilov·C. Mariñas·L. Nemenov·M. Nikitin·K. Okada·V. Olchevskii·M. Pentia·A. Penzo·M. Pló·G. F. Rappazzo·C. Regenfus·J. Rochet·A. Romero·V. Ronjin·A. Ryazantsev·V. Rykalin·J. Saborido·J. Schacher·A. Sidorov·J. Smolik·S. Sugimoto·F. Takeutchi·A. Tarasov·L. Tauscher·T. Trojek·S. Trusov·V. Utkin·O. Vázquez Doce·T. Vrba·V. Yazkov·Y. Yoshimura·M. Zhabitsky·P. Zrelov
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Abstract

We present evidence for the first observation of electromagnetically bound $π^\pm K^\mp$-pairs ($πK$-atoms) with the DIRAC experiment at the CERN-PS. The $πK$-atoms are produced by the 24 GeV/c proton beam in a thin Pt-target and the $π^\pm$ and $K^\mp$-mesons from the atom dissociation are analyzed in a two-arm magnetic spectrometer. The observed enhancement at low relative momentum corresponds to the production of 173 $\pm$ 54 $πK$-atoms. The mean life of $πK$-atoms is related to the s-wave $πK$-scattering lengths, the measurement of which is the goal of the experiment. From these first data we derive a lower limit for the mean life of 0.8 fs at 90% confidence level.

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B. Adeva, L. Afanasyev, Y. Allkofer, C. Amsler, A. Anania, A. Benelli, V. Brekhovskikh, G. Caragheorgheopol, T. Cechak, M. Chiba, P. Chliapnikov, C. Ciocarlan, S. Constantinescu, C. Curceanu, C. Detraz, D. Dreossi, D. Drijard, A. Dudarev, M. Duma, D. Dumitriu, J. L. Fungueiriño, J. Gerndt, A. Gorin, O. Gorchakov, K. Gritsay, C. Guaraldo, M. Gugiu, M. Hansroul, Z. Hons, S. Horikawa, M. Iliescu, V. Karpukhin, J. Kluson, M. Kobayashi, V. Komarov, V. Kruglov, L. Kruglova, A. Kulikov, A. Kuptsov, I. Kurochkin, A. Lamberto, A. Lanaro, V. Lapshin, R. Lednicky, P. Levi Sandri, A. Lopez Aguera, V. Lucherini, I. Manuilov, C. Mariñas, L. Nemenov, M. Nikitin, K. Okada, V. Olchevskii, M. Pentia, A. Penzo, M. Pló, G. F. Rappazzo, C. Regenfus, J. Rochet, A. Romero, V. Ronjin, A. Ryazantsev, V. Rykalin, J. Saborido, J. Schacher, A. Sidorov, J. Smolik, S. Sugimoto, F. Takeutchi, A. Tarasov, L. Tauscher, T. Trojek, S. Trusov, V. Utkin, O. Vázquez Doce, T. Vrba, V. Yazkov, Y. Yoshimura, M. Zhabitsky, P. Zrelov. 2009-05-01. Evidence for $πK$-atoms with DIRAC. https://doi.org/10.1016/j.physletb.2009.03.001

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