Apart2
Apart2[expr]
partial fractions propagators of the form 1/[(q2−m12)(q2−m22)].
See also
Overview, FAD, FeynAmpDenominator, ApartFF.
Examples
FAD[{q, m}, {q, M}, q - p]
Apart2[%]
StandardForm[FCE[%]]
(q2−m2).(q2−M2).(q−p)21
m2−M2(q2−m2).(q−p)21−(q2−M2).(q−p)21
m2−M2FAD[{q,m},−p+q]−FAD[{q,M},−p+q]
Apart2 can also handle Cartesian propagators with square roots. To disable this mode use textSqrttotextFalse
int = CFAD[{{k, 0}, {+m^2, -1}, 1}, {{k - p, 0}, {0, -1}, 1}] GFAD[{{DE - Sqrt[CSPD[k, k]], 1}, 1}]
int // FeynAmpDenominatorCombine // Apart2
(DE−k2+iη)(k2+m2−iη).((k−p)2−iη)1
DE2+m2(k2+m2−iη).((k−p)2−iη)DE+(DE−k2+iη).((k−p)2−iη)1+(k2+m2−iη).((k−p)2−iη)k2