Wednesday, November 7, 2012

1211.1145 (Martin Hoferichter et al.)

Isospin breaking in pion-deuteron scattering and the pion-nucleon
scattering lengths
   [PDF]

Martin Hoferichter, Vadim Baru, Christoph Hanhart, Bastian Kubis, Andreas Nogga, Daniel R. Phillips
In recent years, high-accuracy data for pionic hydrogen and deuterium have become the primary source of information on the pion-nucleon scattering lengths. Matching the experimental precision requires, in particular, the study of isospin-breaking corrections both in pion-nucleon and pion-deuteron scattering. We review the mechanisms that lead to the cancellation of potentially enhanced virtual-photon corrections in the pion-deuteron system, and discuss the subtleties regarding the definition of the pion-nucleon scattering lengths in the presence of electromagnetic interactions by comparing to nucleon-nucleon scattering. Based on the pi^{+/-} p channels we find for the virtual-photon-subtracted scattering lengths in the isospin basis a^{1/2}=(170.5 +/- 2.0) x 10^{-3} mpi^{-1} and a^{3/2}=(-86.5 +/- 1.8) x 10^{-3} mpi^{-1}.
View original: http://arxiv.org/abs/1211.1145

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