title: Precision determination of the dpi<-->NN transition strength at threshold.
abstract: 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.
authors.affiliation: Institut für Kernphysik, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany.
authors.forename: Th
authors.initials: T
authors.lastname: Strauch
authors.forename: F D
authors.initials: FD
authors.lastname: Amaro
authors.forename: D F
authors.initials: DF
authors.lastname: Anagnostopoulos
authors.forename: P
authors.initials: P
authors.lastname: Bühler
authors.forename: D S
authors.initials: DS
authors.lastname: Covita
authors.forename: H
authors.initials: H
authors.lastname: Gorke
authors.forename: D
authors.initials: D
authors.lastname: Gotta
authors.forename: A
authors.initials: A
authors.lastname: Gruber
authors.forename: A
authors.initials: A
authors.lastname: Hirtl
authors.forename: P
authors.initials: P
authors.lastname: Indelicato
authors.forename: E-O
authors.initials: EO
authors.lastname: Le Bigot
authors.forename: M
authors.initials: M
authors.lastname: Nekipelov
authors.forename: J M F
authors.initials: JM
authors.lastname: dos Santos
authors.forename: S
authors.initials: S
authors.lastname: Schlesser
authors.forename: Ph
authors.initials: P
authors.lastname: Schmid
authors.forename: L M
authors.initials: LM
authors.lastname: Simons
authors.forename: M
authors.initials: M
authors.lastname: Trassinelli
authors.forename: J F C A
authors.initials: JF
authors.lastname: Veloso
authors.forename: J
authors.initials: J
authors.lastname: Zmeskal