Observation of π^{-}K^{+} and π^{+}K^{-} Atoms.
The observation of hydrogenlike πK atoms, consisting of π^{-}K^{+} or π^{+}K^{-} mesons, is presented. The atoms are produced by 24  GeV/c protons from the CERN PS accelerator, interacting with platinum or nickel foil targets. The breakup (ionization) of πK atoms in the same targets yields characteristic πK pairs, called "atomic pairs," with small relative momenta Q in the pair center-of-mass system. The upgraded DIRAC experiment observed 349±62 such atomic πK pairs, corresponding to a signal of 5.6 standard deviations. This is the first statistically significant observation of the strange dimesonic πK atom.
Santiago de Compostela University, Santiago de Compostela, Spain.
B
B
Adeva
JINR, Dubna, Russia.
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L
Afanasyev
Zurich University, Zurich, Switzerland.
Y
Y
Allkofer
Albert Einstein Center for Fundamental Physics, Laboratory of High Energy Physics, Bern, Switzerland.
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C
Amsler
INFN, Sezione di Trieste and Messina University, Messina, Italy.
A
A
Anania
IFIN-HH, National Institute for Physics and Nuclear Engineering, Bucharest, Romania.
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S
Aogaki
Czech Technical University in Prague, Prague, Czech Republic.
A
A
Benelli
IHEP, Protvino, Russia.
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V
Brekhovskikh
Czech Technical University in Prague, Prague, Czech Republic.
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T
Cechak
Tokyo Metropolitan University, Tokyo, Japan.
M
M
Chiba
IHEP, Protvino, Russia.
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P
Chliapnikov
Czech Technical University in Prague, Prague, Czech Republic.
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P
Doskarova
CERN, Geneva, Switzerland.
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D
Drijard
JINR, Dubna, Russia.
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A
Dudarev
IFIN-HH, National Institute for Physics and Nuclear Engineering, Bucharest, Romania.
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D
Dumitriu
IFIN-HH, National Institute for Physics and Nuclear Engineering, Bucharest, Romania.
D
D
Fluerasu
IHEP, Protvino, Russia.
A
A
Gorin
JINR, Dubna, Russia.
O
O
Gorchakov
JINR, Dubna, Russia.
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K
Gritsay
INFN, Laboratori Nazionali di Frascati, Frascati, Italy.
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C
Guaraldo
IFIN-HH, National Institute for Physics and Nuclear Engineering, Bucharest, Romania.
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M
Gugiu
CERN, Geneva, Switzerland.
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M
Hansroul
Nuclear Physics Institute ASCR, Rez, Czech Republic.
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Z
Hons
Zurich University, Zurich, Switzerland.
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S
Horikawa
Kyoto University, Kyoto, Japan.
Y
Y
Iwashita
JINR, Dubna, Russia.
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V
Karpukhin
Czech Technical University in Prague, Prague, Czech Republic.
J
J
Kluson
KEK, Tsukuba, Japan.
M
M
Kobayashi
JINR, Dubna, Russia.
V
V
Kruglov
JINR, Dubna, Russia.
L
L
Kruglova
JINR, Dubna, Russia.
A
A
Kulikov
JINR, Dubna, Russia.
E
E
Kulish
JINR, Dubna, Russia.
A
A
Kuptsov
INFN, Sezione di Trieste and Messina University, Messina, Italy.
A
A
Lamberto
University of Wisconsin, Madison, USA.
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A
Lanaro
Institute of Physics ASCR, Prague, Czech Republic.
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R
Lednicky
Santiago de Compostela University, Santiago de Compostela, Spain.
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C
Mariñas
Czech Technical University in Prague, Prague, Czech Republic.
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J
Martincik
JINR, Dubna, Russia.|CERN, Geneva, Switzerland.
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L
Nemenov
JINR, Dubna, Russia.
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M
Nikitin
Kyoto Sangyo University, Kyoto, Japan.
K
K
Okada
JINR, Dubna, Russia.
V
V
Olchevskii
IFIN-HH, National Institute for Physics and Nuclear Engineering, Bucharest, Romania.
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M
Pentia
INFN, Sezione di Trieste, Trieste, Italy.
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A
Penzo
Santiago de Compostela University, Santiago de Compostela, Spain.
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M
Plo
Czech Technical University in Prague, Prague, Czech Republic.
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P
Prusa
INFN, Sezione di Trieste and Messina University, Messina, Italy.
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G
Rappazzo
INFN, Laboratori Nazionali di Frascati, Frascati, Italy.
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A
Romero Vidal
IHEP, Protvino, Russia.
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A
Ryazantsev
IHEP, Protvino, Russia.
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V
Rykalin
Santiago de Compostela University, Santiago de Compostela, Spain.
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J
Saborido
Albert Einstein Center for Fundamental Physics, Laboratory of High Energy Physics, Bern, Switzerland.
J
J
Schacher
IHEP, Protvino, Russia.
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A
Sidorov
Czech Technical University in Prague, Prague, Czech Republic.
J
J
Smolik
Kyoto Sangyo University, Kyoto, Japan.
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F
Takeutchi
Basel University, Basel, Switzerland.
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L
Tauscher
Czech Technical University in Prague, Prague, Czech Republic.
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T
Trojek
Skobeltsin Institute for Nuclear Physics of Moscow State University, Moscow, Russia.
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S
Trusov
Czech Technical University in Prague, Prague, Czech Republic.
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T
Urban
Czech Technical University in Prague, Prague, Czech Republic.
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T
Vrba
Skobeltsin Institute for Nuclear Physics of Moscow State University, Moscow, Russia.
V
V
Yazkov
KEK, Tsukuba, Japan.
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Y
Yoshimura
JINR, Dubna, Russia.
M
M
Zhabitsky
JINR, Dubna, Russia.
P
P
Zrelov