Extraction of the light quark mass ratio from the decays psi'-->J/psipi0(eta)

Light quark masses are important fundamental parameters of the standard model. The decays psi'-->J/psipi0(eta) were widely used in determining the light quark mass ratio m(u)/m(d). However, there is a large discrepancy between the resulting value of m(u)/m(d) and the one determined from the light pseudoscalar meson masses. Using the technique of nonrelativistic effective field theory, we show that intermediate charmed meson loops lead to a sizable contribution to the decays and hence make the psi'-->J/psipi0(eta) decays not suitable for a precise extraction of the light quark mass ratio.