If you tell about fixed value of some 4-vecor or tensor component you assume to deal with some concrete reference system, may be C.M. or Lab-system. In FC you deal with Lorentz invariants. You can calculate the value of LeviCivita tensor (contracted with four 4-vectors) in any system by hands and furthermore to substitute it into FC-calculation.
This archive was generated by hypermail 2b29 : 11/20/17-11:40:01 PM Z CET