#### ${\mathit m}_{{{\mathit s}}}/{\mathit m}_{{{\mathit d}}}$ MASS RATIO

VALUE DOCUMENT ID TECN  COMMENT
 $\bf{ \text{17 - 22}}$ OUR EVALUATION
$20.0$ 1
 1997
THEO
$18.9$ $\pm0.8$ 2
 1996
THEO Compilation
$21$ 3
 1992
THEO
$18$ 4
 1990
THEO
$18\text{ to }23$ 5
 1990 B
THEO
 1 GAO 1997 uses electromagnetic mass splittings of light mesons.
 2 LEUTWYLER 1996 uses a combined fit to ${{\mathit \eta}}$ $\rightarrow$ 3 ${{\mathit \pi}}$ and ${{\mathit \psi}^{\,'}}$ $\rightarrow$ ${{\mathit J / \psi}}$ (${{\mathit \pi}}$ ,${{\mathit \eta}}$ ) decay rates, and the electromagnetic mass differences of the ${{\mathit \pi}}$ and ${{\mathit K}}$ .
 3 DONOGHUE 1992 result is from a combined analysis of meson masses, ${{\mathit \eta}}$ $\rightarrow$ 3 ${{\mathit \pi}}$ using second-order chiral perturbation theory including nonanalytic terms, and ( ${{\mathit \psi}{(2S)}}$ $\rightarrow$ ${{\mathit J / \psi}{(1S)}}{{\mathit \pi}}$ )/( ${{\mathit \psi}{(2S)}}$ $\rightarrow$ ${{\mathit J / \psi}{(1S)}}{{\mathit \eta}}$ ).
 4 GERARD 1990 uses large $\mathit N$ and ${{\mathit \eta}}-{{\mathit \eta}^{\,'}}$ mixing.
 5 LEUTWYLER 1990B determines quark mass ratios using second-order chiral perturbation theory for the meson and baryon masses, including nonanalytic corrections. Also uses Weinberg sum rules to determine $\mathit L_{7}$.
References:
 GAO 1997
PR D56 4115 Electromagnetic Mass Splittings of ${{\mathit \pi}}$ , ${{\mathit a}_{{1}}}$ , ${{\mathit K}}$ , ${{\mathit K}_{{1}}{(1400)}}$ and ${{\mathit K}^{*}{(892)}}$
 LEUTWYLER 1996
PL B378 313 The Ratios of the Light Quark Masses
 DONOGHUE 1992
PRL 69 3444 Mass Ratios of the Light Quarks
 GERARD 1990
MPL A5 391 The Light Quark Current Mass Ratios and ${{\mathit \eta}}$ $\leftrightarrow$ ${{\mathit \eta}^{\,'}}$ Mixing
 LEUTWYLER 1990B
NP B337 108 How About ${\mathit m}_{{{\mathit u}}}$ = 0?