= Flavor-nonsinglet axial Ward identity with equal quark masses
{title2=$\partial_\mu A_a^\mu=mP_a,\quad A_a^\mu=\bar q\gamma^\mu\gamma_5\tau_aq/2$}
For the <Dirac equation> with two equal <quark masses> $m$, the equations for $q$ and $\bar q$ give the divergence of the nonsinglet <axial current> as $im\bar q\gamma_5\tau_aq=mP_a$. The color <chiral anomaly> is absent in this nonsinglet identity because the <quark flavor> generator is traceless. Equivalently, the <mass> term in the <Hamiltonian> is $m\int S\,d^3x$, and the <nonsinglet axial charge algebra of quark densities> gives $\dot Q_{5,a}=m\int P_a\,d^3x$.
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