EPS _ _ _ _ _ _ _ _ _ _ _ _ operator

The eps operator denotes the completely antisymmetric tensor of order 4 and its contraction with Lorentz four-vectors, as used in high-energy physics calculations.

syntax:

eps(<vector-expr>,<vector-expr>,<vector-expr>, <vector-expr>)

<vector-expr> must be a valid vector expression, and may be an index.

examples:

vector g0,g1,g2,g3; 

eps(g1,g0,g2,g3); 

  - EPS(G0,G1,G2,G3); 


eps(g1,g2,g0,g3); 

  EPS(G0,G1,G2,G3); 


eps(g1,g2,g3,g1); 

  0

Vector identifiers are ordered alphabetically by REDUCE. When an o dd number of transpositions is required to restore the canonical order to the four arguments of eps, the term is ordered and carries a minus sign. When an even number of transpositions is required, the term is returned ordered and positive. When one of the arguments is repeated, the value 0 is returned. A contraction of the form eps(_i j mu nu p_mu q_nu) is represented by eps(i,j,p,q) when i and j have been declared to be of type index.