R symmetry. Given a supersymmetric gauge theory (abelian or nonabelian), consider a global U(1) transformation that changes the phase of the gaugino fields, λa→e−iαλa; we say that the gauginos have R charge +1.
a) If R symmetry is to be a good symmetry of the lagrangian, what relation must hold between the R charges of the scalar and fermion components of a chiral superfield that couples to the gauge fields?
b) In additon, what conditions must be placed on the superpotential?
c) Identify the R symmetry, if any, of supersymmetric quantum electrodynamics.