Using ReplaceAll in FeynCalc

[sunnyasquabla]

Hi,
I am trying to simply an expression for which I have collected Epsilon(p1) . Epsilon(p2) as shown below.

Now I want to take these Epsilon(p1) . Epsilon(p2) term to zero to extract the relevant part that I need.
For this I use ReplaceAll, but it takes every epsilon to zero.

I want to keep terms like (p1. Epsilon(p2)) (p1Epsilon(p1)) for further calculations.
Can someone tell me how to do that?
I'll be very thankful to you.

[vsht]

Hi,

just use something like

ReplaceAll[#, 
  Pair[Momentum[Polarization[p1, __]], 
    Momentum[Polarization[p2, __]]] :> 0] &

and so on/

[sunnyasquabla]

Hey,

The above command didn't work
But this one worked,

ReplaceAll[#, Pair[Momentum[Polarization[___], ___], Momentum[Polarization[___], ___], ___] -> 0]

I want to know, how do I decide where to put the underscores?
Thanks

[vsht]

I want to know, how do I decide where to put the underscores?

This is not a question about FeynCalc but rather how pattern matching works in Mathematica. I'd suggest that you
first familiarize yourself with the concept of replacement rules and patterns, otherwise you will not get far trying to use FeynCalc.
Also, mathematica.stackexchange.com is probably a better place for such inquiries.

[sunnyasquabla]

Alright,
Thank you.