Here\[{{\rm{\beta }}^{\rm{ - }}}\]decay is
\[(ud)d \to (ud)u + {e^ - } + {\bar \nu _e}\]
I,\[{{\rm{\beta }}^{\rm{ - }}}\]decay is where we spelled out the neutron and proton in terms of their quark components.
Where, we wrote out the neutron and proton in terms of their quark constituents, i.e. \[{\rm{n = udd and }}{{\rm{p}}^{\rm{ + }}}{\rm{ = udu}}\]. On the other hand, \[{{\rm{\beta }}^{\rm{ + }}}\]decay is given with\[(ud)u \to (ud)d + {e^ + } + {\nu _e}\]
A proton \[{{\rm{p}}^{\rm{ + }}}{\rm{ = udu}}\]has been transformed into a neutrino \[{{\rm{p}}^{\rm{ + }}}{\rm{ = udu}}\]. This reaction may be generated from (1) by moving particles from the right to the left side and "crossing to the opposite side." Because particles transform into their antiparticles in this operation, our electron \[{{\rm{e}}^{\rm{ - }}}\]became a positron \[{{\rm{e}}^{\rm{ + }}}\]and our electron antineutrino \[{{\rm{\bar \nu }}_{\rm{e}}}\]became a neutrino \[{{\rm{\nu }}_{\rm{e}}}\]. In most cases, a response can occur in both directions. We infer that in \[{{\rm{\beta }}^{\rm{ + }}}\]decay, the reverse flavor change happens.