1/2 a^{a1,a2,a3}_{a0} b^{}_{a4,v0} eta1^{a4}_{a3} a+(a0) a+(v0) a-(a2) a-(a1)
+1/2 a^{a0,a2,a3}_{a1} b^{}_{a4,v0} lambda2^{a1,a4}_{a2,a3} a+(v0) a-(a0)