Name: Lingxiao Xu Date: 11/26/14-05:34:58 AM Z


Hi,
Thanks for attention.
 Here is one of my results which cantains Levi-Civita tensor contracted with four-momentums,

1/(8 s t
\!\(\*SubsuperscriptBox[\(m\), \(W\), \(4\)]\))
  g^4 sw^2 (s^2 t^2 - t^4 + s^2 t u + t^3 u + t^2 u^2 - t u^3 -
    8 s^2 t
\!\(\*SubsuperscriptBox[\(m\), \(W\), \(2\)]\) + 4 s t^2
\!\(\*SubsuperscriptBox[\(m\), \(W\), \(2\)]\) - 4 s^2 u
\!\(\*SubsuperscriptBox[\(m\), \(W\), \(2\)]\) - 4 s t u
\!\(\*SubsuperscriptBox[\(m\), \(W\), \(2\)]\) - 4 t^2 u
\!\(\*SubsuperscriptBox[\(m\), \(W\), \(2\)]\) + 4 u^3
\!\(\*SubsuperscriptBox[\(m\), \(W\), \(2\)]\) +
    8 I t Eps[Momentum[p1], Momentum[p2], Momentum[-p1 - p2 - p3],
      Momentum[p3]]
\!\(\*SubsuperscriptBox[\(m\), \(W\), \(2\)]\) +
    8 I t Eps[Momentum[p1], Momentum[p2], Momentum[p3],
      Momentum[p3 - p4]]
\!\(\*SubsuperscriptBox[\(m\), \(W\), \(2\)]\) +
    8 I t Eps[Momentum[p1], Momentum[p3], Momentum[p4],
      Momentum[p1 + p2 + p4]]
\!\(\*SubsuperscriptBox[\(m\), \(W\), \(2\)]\) + 12 s^2
\!\(\*SubsuperscriptBox[\(m\), \(W\), \(4\)]\) + 16 s t
\!\(\*SubsuperscriptBox[\(m\), \(W\), \(4\)]\) - 12 t^2
\!\(\*SubsuperscriptBox[\(m\), \(W\), \(4\)]\) + 16 s u
\!\(\*SubsuperscriptBox[\(m\), \(W\), \(4\)]\) + 8 t u
\!\(\*SubsuperscriptBox[\(m\), \(W\), \(4\)]\) - 12 u^2
\!\(\*SubsuperscriptBox[\(m\), \(W\), \(4\)]\) -
    16 I Eps[Momentum[p1], Momentum[p2], Momentum[-p1 - p2 - p3],
      Momentum[p3]]
\!\(\*SubsuperscriptBox[\(m\), \(W\), \(4\)]\) +
    8 I Eps[Momentum[p1], Momentum[p2], Momentum[p3],
      Momentum[p3 - p4]]
\!\(\*SubsuperscriptBox[\(m\), \(W\), \(4\)]\) +
    8 I Eps[Momentum[p1], Momentum[p2], Momentum[p3],
      Momentum[p1 + p2 + p4]]
\!\(\*SubsuperscriptBox[\(m\), \(W\), \(4\)]\) -
    8 I Eps[Momentum[p1], Momentum[p3], Momentum[p4],
      Momentum[p1 + p2 + p4]]
\!\(\*SubsuperscriptBox[\(m\), \(W\), \(4\)]\) - 56 s
\!\(\*SubsuperscriptBox[\(m\), \(W\), \(6\)]\) + 24 t
\!\(\*SubsuperscriptBox[\(m\), \(W\), \(6\)]\) + 8 u
\!\(\*SubsuperscriptBox[\(m\), \(W\), \(6\)]\) - 16
\!\(\*SubsuperscriptBox[\(m\), \(W\), \(8\)]\) -
    4 I (s - t - u) Eps[Momentum[p1], Momentum[p2], Momentum[p3],
      Momentum[p4]] (t - 2
\!\(\*SubsuperscriptBox[\(m\), \(W\), \(2\)]\)) +
    4 I Eps[Momentum[p1], Momentum[p2], Momentum[p3 - p4],
      Momentum[p4]] (s t - 2 (s + t + u)
\!\(\*SubsuperscriptBox[\(m\), \(W\), \(2\)]\) + 6
\!\(\*SubsuperscriptBox[\(m\), \(W\), \(4\)]\)))

So in this kind of condition, how can I simplify the Levi-Civita tensor further?

Best Regards!
Lingxiao