Charge-symmetry-breaking corrections to pseudoscalar meson-nucleon coupling constants due to up-down current quark mass difference and their effects on NN scattering lengths.

Abstract

The charge-symmetry-breaking corrections due to the isospin breaking part of the quantum chromodynamic Hamiltonian, determined by the up-down current quark mass difference, ${H}_{\mathrm{QCD}=\mathrm{half}({m}_{u}\mathrm{\ensuremath{-}}{m}_{d})(\mathrm{\ifmmode \bar{u}\else \={u}\fi{}}\mathrm{u}\mathrm{\ensuremath{-}}\mathrm{d}\mathrm{\ifmmode\bar\else\textasciimacron\fi{}}\mathrm{d}}$), on \ensuremath{\pi}NN and \ensuremath{\eta}NN coupling constants and their effect on (\ensuremath{\delta}a${)}_{\mathrm{CSB}={a}_{\mathrm{pp}}\mathrm{\ensuremath{-}}{a}_{\mathrm{nn}}}$ are estimated. The effects of ${H}_{\mathrm{QCD}}$ on the pseudoscalar meson-nucleon coupling constants are calculated via ${\ensuremath{\pi}}^{0}$-\ensuremath{\eta},\ensuremath{\eta}' mixing, giving rise to charge-symmetry-breaking one-boson-exchange [one-pion-exchange and one-\ensuremath{\eta}-exchange] and two-boson-exchange [two-pion-exchange, \ensuremath{\pi}\ensuremath{\eta}-exchange etc.] potentials. The importance of charge-symmetry-breaking two-boson exchange is emphasized.