SPLN
SPLN[p,q,n,nb]
denotes the negative component in the lightcone decomposition of the scalar product p⋅q along the vectors n
and nb
. It corresponds to 21(p⋅nˉ)(q⋅n).
If one omits n
and nb
, the program will use default vectors specified via $FCDefaultLightconeVectorN
and $FCDefaultLightconeVectorNB
.
See also
Overview, Pair, FVLN, FVLP, FVLR, SPLP, SPLR, MTLP, MTLN, MTLR.
Examples
21(n⋅q)(nb⋅p)
StandardForm[SPLN[p, q, n, nb] // FCI]
21Pair[Momentum[n],Momentum[q]]Pair[Momentum[nb],Momentum[p]]
Notice that the properties of n
and nb
vectors have to be set by hand before doing the actual computation
SPLN[p1 + p2 + n, q, n, nb] // ExpandScalarProduct
21(n⋅q)(n⋅nb+nb⋅p1+nb⋅p2)
FCClearScalarProducts[]
SP[n] = 0;
SP[nb] = 0;
SP[n, nb] = 2;
SPLN[p1 + p2 + n, q, n, nb] // ExpandScalarProduct
21(n⋅q)(nb⋅p1+nb⋅p2+2)