Isospin breaking in pion-nucleon scattering at threshold by radiative processes

Mar, 2005
9 pages
e-Print:
Report number:
  • CERN-PH-TH-2005-048

Citations per year

20052006200751
Abstract:
We investigate the dispersive contribution by radiative processes such as (pi- proton to neutron gamma) and (pi- proton to Delta gamma) to the pion-nucleon scattering lengths of charged pions in the heavy baryon limit. They give a large isospin violating contribution in the corresponding isoscalar scattering length, but only a small violation in the isovector one. These terms contribute 6.3(3)% to the 1s level shift of pionic hydrogen and give a chiral constant F_pi^2f_1=-25.8(8) MeV.
  • 13.75.Gx
  • 11.55.Ds
  • 11.10.Ef
  • 36.10.Gv
  • pi- p: inelastic scattering
  • pi-: absorption
  • photon: hadroproduction
  • Delta(1232)0: hadroproduction
  • pi- p: elastic scattering
  • pi nucleon: scattering length