## Mandelstam

`Mandelstam` is an option for `DiracTrace`, `OneLoop`, `OneLoopSum` and `TrickMandelstam`.  A typical setting is `Mandelstam -> {s, t, u, m1^2+m2^2+m3^2+m4^2}`, which implies $s + t + u = m_1^2+m_2^2+m_3^2+m_4^2$. If other than four-particle processes are calculated, the setting should be `Mandelstam -> {}`.

### See also

[Overview](Extra/FeynCalc.md), [DiracTrace](DiracTrace.md), [OneLoop](OneLoop.md), [OneLoopSum](OneLoopSum.md), [TrickMandelstam](TrickMandelstam.md), [SetMandelstam](SetMandelstam.md).

### Examples