-1/8 a^{a0,a1}_{c3,a3} b^{c0,c3}_{v0,v1} c^{a2,a4}_{c1,c2} gamma1^{a3}_{a4} a+(c1) a+(c2) a+(v0) a+(v1) a-(a2) a-(a1) a-(a0) a-(c0)