R4alphabeta[x_]=a0+a1 x+a2 x^2-4 s x^3+x^4;
a0=-1-a2;
a1=-L4+4 s;
a2=1/4 (-4+32 s^2-4 s \[Alpha]-\[Alpha]^2-4 s \[Beta]+2 \[Alpha] \[Beta]-\[Beta]^2);
L4=1/4 (-1+\[Beta]) (32 s^2-\[Alpha]^2+2 \[Alpha] \[Beta]+3 \[Beta]^2-4 s (\[Alpha]+5 \[Beta]));