FCShowEpsilon[expr] substitutes
SMP["Delta"] with
1/Epsilon - EulerGamma + Log[4 Pi].
SMP["Delta"]
FCShowEpsilon[%]\Delta
\frac{1}{\varepsilon }-\gamma +\log (4 \pi )
SMP["Delta_UV"]
FCShowEpsilon[%]\Delta _{\text{UV}}
\frac{1}{\varepsilon _{\text{UV}}}-\gamma +\log (4 \pi )
SMP["Delta_IR"]
FCShowEpsilon[%]\Delta _{\text{IR}}
\frac{1}{\varepsilon _{\text{IR}}}-\gamma +\log (4 \pi )