PaXEvaluateIR[expr,q] is like PaXEvaluate
but with the difference that it returns only the IR-divergent part of
the result.
Overview, PaXEvaluate, PaXEvaluateUV, PaXEvaluateUVIRSplit.
PaXEvaluateIR[B0[SPD[p], 0, m^2], PaXSeries -> {{SPD[p], m^2, 1}}, PaXAnalytic -> True]\frac{1}{2 \varepsilon _{\text{IR}}}-\frac{p^2}{2 m^2 \varepsilon _{\text{IR}}}