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First Measurement of a Long-Lived π^{+}π^{-} Atom Lifetime.

  • Adeva B Santiago de Compostela University, Santiago de Compostela, Spain.
  • Afanasyev L JINR, Dubna, Russia.
  • Anania A INFN, Sezione di Trieste and Messina University, Messina, Italy.
  • Aogaki S IFIN-HH, National Institute for Physics and Nuclear Engineering, Bucharest, Romania.
  • Benelli A Czech Technical University in Prague, Prague, Czech Republic.
  • Brekhovskikh V IHEP, Protvino, Russia.
  • Cechak T Czech Technical University in Prague, Prague, Czech Republic.
  • Chiba M Tokyo Metropolitan University, Tokyo, Japan.
  • Chliapnikov PV IHEP, Protvino, Russia.
  • Doskarova P Czech Technical University in Prague, Prague, Czech Republic.
  • Drijard D CERN, Geneva, Switzerland.
  • Dudarev A JINR, Dubna, Russia.
  • Dumitriu D IFIN-HH, National Institute for Physics and Nuclear Engineering, Bucharest, Romania.
  • Fluerasu D IFIN-HH, National Institute for Physics and Nuclear Engineering, Bucharest, Romania.
  • Gorin A IHEP, Protvino, Russia.
  • Gorchakov O JINR, Dubna, Russia.
  • Gritsay K JINR, Dubna, Russia.
  • Guaraldo C INFN, Laboratori Nazionali di Frascati, Frascati, Italy.
  • Gugiu M IFIN-HH, National Institute for Physics and Nuclear Engineering, Bucharest, Romania.
  • Hansroul M CERN, Geneva, Switzerland.
  • Hons Z Nuclear Physics Institute ASCR, Rez, Czech Republic.
  • Horikawa S Zurich University, Zurich, Switzerland.
  • Iwashita Y Kyoto University, Kyoto, Japan.
  • Karpukhin V JINR, Dubna, Russia.
  • Kluson J Czech Technical University in Prague, Prague, Czech Republic.
  • Kobayashi M KEK, Tsukuba, Japan.
  • Kruglov V JINR, Dubna, Russia.
  • Kruglova L JINR, Dubna, Russia.
  • Kulikov A JINR, Dubna, Russia.
  • Kulish E JINR, Dubna, Russia.
  • Lamberto A INFN, Sezione di Trieste and Messina University, Messina, Italy.
  • Lanaro A CERN, Geneva, Switzerland.
  • Lednicky R Institute of Physics ASCR, Prague, Czech Republic.
  • Mariñas C Santiago de Compostela University, Santiago de Compostela, Spain.
  • Martincik J Czech Technical University in Prague, Prague, Czech Republic.
  • Nemenov L JINR, Dubna, Russia.
  • Nikitin M JINR, Dubna, Russia.
  • Okada K Kyoto Sangyo University, Kyoto, Japan.
  • Olchevskii V JINR, Dubna, Russia.
  • Ovsiannikov V Voronezh State University, Voronezh, Russia.
  • Pentia M IFIN-HH, National Institute for Physics and Nuclear Engineering, Bucharest, Romania.
  • Penzo A INFN, Sezione di Trieste, Trieste, Italy.
  • Plo M Santiago de Compostela University, Santiago de Compostela, Spain.
  • Prusa P Czech Technical University in Prague, Prague, Czech Republic.
  • Rappazzo GF INFN, Sezione di Trieste and Messina University, Messina, Italy.
  • Romero Vidal A Santiago de Compostela University, Santiago de Compostela, Spain.
  • Ryazantsev A IHEP, Protvino, Russia.
  • Rykalin V IHEP, Protvino, Russia.
  • Saborido J Santiago de Compostela University, Santiago de Compostela, Spain.
  • Schacher J Albert Einstein Center for Fundamental Physics, LHEP, Bern, Switzerland.
  • Sidorov A IHEP, Protvino, Russia.
  • Smolik J Czech Technical University in Prague, Prague, Czech Republic.
  • Takeutchi F Kyoto Sangyo University, Kyoto, Japan.
  • Trojek T Czech Technical University in Prague, Prague, Czech Republic.
  • Trusov S Skobeltsin Institute for Nuclear Physics of Moscow State University, Moscow, Russia.
  • Urban T Czech Technical University in Prague, Prague, Czech Republic.
  • Vrba T Czech Technical University in Prague, Prague, Czech Republic.
  • Yazkov V Skobeltsin Institute for Nuclear Physics of Moscow State University, Moscow, Russia.
  • Yoshimura Y KEK, Tsukuba, Japan.
  • Zrelov P JINR, Dubna, Russia.
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  • 2019-04-02
Published in:
  • Physical review letters. - 2019
General Physics and Astronomy
English The adapted DIRAC experiment at the CERN PS accelerator observed for the first time long-lived hydrogenlike π^{+}π^{-} atoms, produced by protons hitting a beryllium target. A part of these atoms crossed the gap of 96 mm between the target and a 2.1  μm thick platinum foil, in which most of them dissociated. Analyzing the observed number of atomic pairs, n_{A}^{L}=436_{-61}^{+157}|_{tot}, the lifetime of the 2p state is found to be τ_{2p}=(0.45_{-0.30}^{+1.08}|_{tot})×10^{-11}  s, not contradicting the corresponding QED 2p state lifetime τ_{2p}^{QED}=1.17×10^{-11}  s. This lifetime value is three orders of magnitude larger than our previously measured value of the π^{+}π^{-} atom ground state lifetime τ=(3.15_{-0.26}^{+0.28}|_{tot})×10^{-15}  s. Further studies of long-lived π^{+}π^{-} atoms will allow us to measure energy differences between p and s atomic states and so to discriminate between the isoscalar and isotensor ππ scattering lengths with the aim to check QCD predictions.
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hybrid
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https://sonar.ch/global/documents/191343
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