Dirac equation for proton/neutron

[paweld]

Is it possible to incorporate into Dirac equation for proton
the possibility of its transformation into neutron (isospin freedom)?

[tom.stoer]

Is it possible to incorporate into Dirac equation for proton
the possibility of its transformation into neutron (isospin freedom)?
There were attempts to formulate (effective) nucleon theories, but all these theories turned out to be non-renormalizable. One must use QCD based on quarks and gluons instead. But turning a proton into a neutron (an u- into a d-quark) requires electro-weak theory as only W-bosons change flavours.