CovariantD[mu, a, b] is the covariant derivative for a bosonic field. CovariantD[mu] is the covariant derivative for a fermionic field. CovariantD[OPEDelta, a, b] is a short form for CovariantD[mu,a,b]*FourVector[OPEDelta, mu]. CovariantD[{OPEDelta, a, b}, {n}] yields the product of m operators., where n is an integer. CovariantD[OPEDelta, a, b, {m, n}] gives the expanded form of CovariantD[OPEDelta, a, b]^m up to order g^n for the gluon, where n is an integer and g the couplingconstant indicated by the setting of the option CouplingConstant. CovariantD[OPEDelta, {m, n}] gives the expanded form of CovariantD[OPEDelta]^m up to order g^n of the fermionic field.
![[Graphics:Images/index_gr_1.gif]](Images/index_gr_1.gif)
Possible settings of PartialD are: LeftPartialD, LeftRigthPartialD, RightPartialD. The default setting of QuantumField is GaugeField.
See also: LeftPartialD, LeftRightPartialD, RightPartialD.
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The first argument of CovariantD is intepreted as type LorentzIndex, except for OPEDelta, which is type Momentum.
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This givesthe partial derivative
contracted with
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The expansion up to first order in the coupling constant
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The expansion up to second order in the
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