QUARKS INSPIRE   JSON PDGID:
Q002

${\mathit {\mathit u}}$

$I(J^P)$ = $1/2(1/2^{+})$ 
Mass ${\mathit m}_{\mathrm {}}$ = $2.16$ $\pm0.07$ (MeV) Charge = ${2\over 3}$ $\mathit e$ $\mathit I_{\mathit z}$ = $+{1\over 2}$
${\mathit m}_{{{\mathit u}}}/{\mathit m}_{{{\mathit d}}}$ = $0.462 \pm0.020 $   
${\mathit {\mathit u}}$-QUARK MASS [1] $2.16$ $\pm0.07$ MeV  CL=90%
 
[1] The ratios ${\mathit m}_{{{\mathit u}}}/{\mathit m}_{{{\mathit d}}}$ and ${\mathit m}_{{{\mathit s}}}/{\mathit m}_{{{\mathit d}}}$ are extracted from pion and kaon masses using chiral symmetry. The estimates of ${{\mathit u}}$ and ${{\mathit d}}$ masses are not without controversy and remain under active investigation. Within the literature there are even suggestions that the ${{\mathit u}}~$quark could be essentially massless. The ${{\mathit s}}$-quark mass is estimated from SU(3) splittings in hadron masses.