Momentum

Description

Momentum[p] is the head of a four momentum (p). The internal representation of a four-dimensional p is Momentum[p]. For other than four dimensions: Momentum[p, dim]. Momentum[p, 4] simplifies to Momentum[p].

See also:  DiracGamma, Eps, LorentzIndex, MomentumExpand.

Examples

This is a four dimensional momentum.

Momentum[p]

As an optional second argument the dimension must be specified if it is different from 4.

Momentum[p, D]

The dimension index is supressed in the output.

Momentum[p, d] // StandardForm

a1 = Momentum[-q]

a1 // StandardForm

a2  =  Momentum[p - q]  +  Momentum[2  q]

a2 // StandardForm

a2 // MomentumExpand // StandardForm

a2 // MomentumCombine // StandardForm

ChangeDimension[Momentum[p], d] // StandardForm

Clear[a1, a2]