Quark mass differences andρ−ωmixing

Abstract

The experimental data on $\rho -\omega$ mixing are reanalyzed in order to extract a new value for the ratio $r_{-}=\frac{(m_d-m_u)}{2m_s}$, where $m_i$ is the current quark mass of quark $i$. After correcting for the purely electromagnetic contribution to the mixing, one obtains $r_{-}=0.010\mathrm{}\pm 0.002$, which agrees well with the average $r_{-}=0.014\mathrm{}\pm 0.003$ obtained previously from kaon and baryon mass differences and the $\eta \to 3\pi$ decay and disagrees substantially with the value ±(0.031±0.007) that would be required if $m_u$ or $m_d$ were zero. A new determination of the current quark mass ratios, including the effects of $\rho -\omega$ mixing, then yields $\frac{m_u}{m_d}=0.47\mathrm{}\pm 0.11$ and $\frac{m_d}{m_s}=0.042\mathrm{}\pm 0.007$.