Quark flavor
= Quark flavor
{title2=$u,d,s,c,b,t$}
= Quark flavour
{synonym}
A quark flavor is one of the six <Standard Model> quark species: up, down, strange, charm, bottom and top. Each flavor occurs in three colour states and is counted as one Dirac species when both chiralities are included. The active flavor number in a low-energy <QCD> description excludes quarks heavier than the relevant scale, with matching of the <running coupling> when a heavy threshold is crossed.