FeynCalc manual (development version)

OneLoop

OneLoop[q, amplitude] calculates the 1-loop Feynman diagram amplitude. The argument q denotes the integration variable, i.e., the loop momentum. OneLoop[name, q, amplitude] has as first argument a name of the amplitude. If the second argument has head FeynAmp then OneLoop[q, FeynAmp[name, k, expr]] and OneLoop[FeynAmp[name, k, expr]] tranform to OneLoop[name, k, expr]. OneLoop is deprecated, please use TID instead!

See also

Overview, ToPaVe, ToPaVe2, A0, A00, B0, B1, B00, B11, C0, D0.

Examples

-I/Pi^2 FAD[{q, m}] 
 
OneLoop[q, %]

-\frac{i}{\pi ^2 \left(q^2-m^2\right)}

\text{A}_0\left(m^2\right)

I ((el^2)/(16 Pi^4 (1 - D))) FAD[{q, mf}, {q - k, mf}] DiracTrace[(mf + GSD[q - k]) . GAD[\[Mu]] . (mf + GSD[q]) . GAD[\[Mu]]] 
 
OneLoop[q, %]

\frac{i \;\text{el}^2 \;\text{tr}\left((\gamma \cdot (q-k)+\text{mf}).\gamma ^{\mu }.(\text{mf}+\gamma \cdot q).\gamma ^{\mu }\right)}{16 \pi ^4 (1-D) \left(q^2-\text{mf}^2\right).\left((q-k)^2-\text{mf}^2\right)}

\frac{\text{el}^2 \left(-\frac{8 \;\text{mf}^2 \;\text{B}_0\left(\overline{k}^2,\text{mf}^2,\text{mf}^2\right)}{1-D}+\frac{2 (2-D) \overline{k}^2 \;\text{B}_0\left(\overline{k}^2,\text{mf}^2,\text{mf}^2\right)}{1-D}+\frac{4 D \;\text{A}_0\left(\text{mf}^2\right)}{1-D}-\frac{8 \;\text{A}_0\left(\text{mf}^2\right)}{1-D}\right)}{16 \pi ^2}