Quit[]

<<FeynCalc`

DeclareNonCommutative[L,R];
L=ChiralityProjector[-1];
R=ChiralityProjector[+1];

dm[mu_]:=GAD[mu]
ds[p_]:=GSD[p]
IDm=L+R;
sp[p_,q_]:=ScalarProduct[p,q,Dimension->D]
prop[p_,m_]:=GSD[p]+IDm*m;
(*PV[k_,μ_]:=PolarizationVector[k,μ]*)
Proj[gL_,gR_]:=gL*L+gR*R;

ScalarProduct[pN,pN]=mN^2;
ScalarProduct[pG,pG]=0;
ScalarProduct[pN,pG]=mA^2/2;
ScalarProduct[pG,pN]=mA^2/2;

CμF[μ_]:=(FVD[pN,μ]+FVD[pG,μ]) C1F+FVD[pN,μ] C2F
CμνF[μ_,ν_]:=MTD[μ,ν] C00F+(FVD[pN,μ]+FVD[pG,μ]) (FVD[pN,ν]+FVD[pG,ν]) C11F+FVD[pN,μ] FVD[pN,ν] C22F+((FVD[pN,μ]+FVD[pG,μ]) FVD[pN,ν]+FVD[pN,μ] (FVD[pN,ν]+FVD[pG,ν])) C12F

AmpF=(I Q)/(16 π^2)Contract[DiracSimplify[Proj[g2L,g2R],dm[ρ],dm[μ],dm[σ],Proj[g1L,g1R]] (CμνF[ρ,σ]+FVD[pN,ρ] CμF[σ]+FVD[pG+pN,σ] CμF[ρ]+FVD[pN,ρ] FVD[pN+pG,σ] C0F)+mF*DiracSimplify[Proj[g2L,g2R],dm[ρ],dm[μ],Proj[g1L,g1R]] (CμF[ρ]+FVD[pN,ρ] C0F)+mF*DiracSimplify[Proj[g2L,g2R],dm[μ],dm[σ],Proj[g1L,g1R]] (CμF[σ]+(FVD[pN,σ]+FVD[pG,σ]) C0F)+mF^2*DiracSimplify[Proj[g2L,g2R],dm[μ],Proj[g1L,g1R]] C0F];

AmpFconj=-((I Q)/(16 π^2))Contract[DiracSimplify[Proj[Conjugate[g1R],Conjugate[g1L]],dm[β],dm[μ],dm[α],Proj[Conjugate[g2L],Conjugate[g2L]]] (CμνF[α,β]+FVD[pN,α] CμF[β]+FVD[pG+pN,β] CμF[α]+FVD[pN,α] FVD[pN+pG,β] C0F)+mF*DiracSimplify[Proj[Conjugate[g1R],Conjugate[g1L]],dm[β],dm[μ],Proj[Conjugate[g2L],Conjugate[g2L]]] (CμF[β]+FVD[pN,β] C0F)+mF*DiracSimplify[Proj[Conjugate[g1R],Conjugate[g1L]],dm[μ],dm[α],Proj[g1L,g1R]] (CμF[α]+(FVD[pN,α]+FVD[pG,α]) C0F)+mF^2*DiracSimplify[Proj[Conjugate[g1R],Conjugate[g1L]],dm[μ],Proj[g1L,g1R]] C0F];

AmpF2=Contract[prop[pG+pN,mA]. AmpFconj .prop[pN,mN] .AmpF];

res=DiracTrace[AmpF2,DiracTraceEvaluate->True,FCVerbose->1];

res