Precision determination of the dpi<-->NN transition strength at threshold.
An unusual but effective way to determine at threshold the dpi<-->NN transition strength alpha is to exploit the hadronic ground-state broadening Gamma(1s) in pionic deuterium, accessible by x-ray spectroscopy. The broadening is dominated by the true absorption channel dpi(-)-->nn, which is related to s-wave pion production pp-->dpi(+) by charge symmetry and detailed balance. Using the exotic atom circumvents the problem of Coulomb corrections to the cross section as necessary in the production experiments. Our dedicated measurement finds Gamma(1s)=(1171(-49)(+23)) meV yielding alpha=(252(-11)(+5)) microb.
Strauch
Th
T
Institut für Kernphysik, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany.
Amaro
F D
FD
Anagnostopoulos
D F
DF
Bühler
P
P
Covita
D S
DS
Gorke
H
H
Gotta
D
D
Gruber
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Hirtl
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A
Indelicato
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Le Bigot
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EO
Nekipelov
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dos Santos
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Schlesser
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Schmid
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Simons
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Trassinelli
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Veloso
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Zmeskal
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