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Determination of the pion-nucleon coupling constant and scattering lengths

Abstract : We critically evaluate the isovector GMO sum rule for forward pion-nucleon scattering using the recent precision measurements of negatively charged pion-proton and pion-deuteron scattering lengths from pionic atoms. We deduce the charged-pion-nucleon coupling constant, with careful attention to systematic and statistical uncertainties. This determination gives, directly from data a pseudoscalar coupling constant of 14.11+-0.05(statistical)+-0.19(systematic) or a pseudovector one of 0.0783(11). This value is intermediate between that of indirect methods and the direct determination from backward neutron-proton differential scattering cross sections. We also use the pionic atom data to deduce the coherent symmetric and antisymmetric sums of the negatively charged pion-proton and pion-neutron scattering lengths with high precision. The symmetric sum gives 0.0012+-0.0002(statistical)+-0.0008 (systematic) and the antisymmetric one 0.0895+-0.0003(statistical)+-0.0013(systematic), both in units of inverse charged pion-mass. For the need of the present analysis, we improve the theoretical description of the pion-deuteron scattering length.
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Contributor : Dominique Girod <>
Submitted on : Tuesday, December 4, 2007 - 2:49:05 PM
Last modification on : Saturday, April 11, 2020 - 2:04:23 AM

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T. E. O. Ericson, B. Loiseau, A. W. Thomas. Determination of the pion-nucleon coupling constant and scattering lengths. Physical Review C, American Physical Society, 2002, 66, pp.014005. ⟨10.1103/PhysRevC.66.014005⟩. ⟨in2p3-00193736⟩



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