4 PLEASE SOLVE STEP BY STEP ONLY IF YOU SURE OF THE SOLUTION PLEASE. THANKS

Problem 4 (extra credits, 20 points) Derive the Feynman propagator SF(-y) for the Dirac field: Sp(3 ) = 1275*=m+ie dp (+ m)e-ip(x,y) dp e-p(-y) (21) - m +ie Problem 4 (extra credits, 20 points) Derive the Feynman propagator SF(-y) for the Dirac field: Sp(3 ) = 1275*=m+ie dp (+ m)e-ip(x,y) dp e-p(-y) (21) - m +ie