On the extraction of the quark mass ratio (md-mu)/ms from Γ(η′→π0π+π-)/Γ(η′→ηπ+ π-)

The claim that the light quark mass ratio (m(d) - m(u))/m(s) can be extracted from the decay width ratio Gamma(eta' -> pi(0)pi(+)pi(-))/Gamma(eta' -> eta pi(+)pi(-)) is critically investigated within a U(3) chiral unitary framework. The influence of the recent VES data on the eta' -> eta pi(+)pi(-) decay is also discussed. (c) 2006 Elsevier B.V. All rights reserved.