Tensor[KroneckerDeltaSpinor] - create the Kronecker delta spinor
Calling Sequences
KroneckerDeltaSpinor(spinorType, ,fr)
Parameters
spinorType - a string, either "spinor" or "barspinor"
fr - (optional) the name of a defined frame
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Description
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The Kronecker delta spinor is the type (1,1) spinor whose components in any coordinate system are given by the identity matrix.
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The command KroneckerDeltaSpinor(spinorType) returns a Kronecker delta spinor of the type specified by spinorType in the current frame unless the frame is explicitly specified.
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This command is part of the DifferentialGeometry:-Tensor package, and so can be used in the form KroneckerDeltaSpinor(...) only after executing the commands with(DifferentialGeometry); with(Tensor); in that order. It can always be used in the long form DifferentialGeometry:-Tensor:-KroneckerDeltaSpinor.
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Examples
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Example 1.
First create a vector bundle M with base coordinates [x, y, z, t] and fiber coordinates [z1, z2, w1, w2].
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| (2.1) |
Here are the 2 Kronecker delta spinors one can define:
M >
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M >
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Define some other manifold N.
M >
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The current frame is N. Because there are no fiber variables, one cannot calculate a Kronecker delta spinor in this frame. To now re-calculate the Kronecker delta spinor KK1, either use the ChangeFrame command or pass KroneckerDeltaSpinor the frame name M as a second argument.
N >
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| (2.5) |
Example 2.
The Kronecker delta spinor defines an identity mapping on spinors of the indicated type. The linear transformation associated to the Kronecker delta spinor K is defined by contracting the covariant index of K against the contravariant index of the spinor S1. We see that the result is S2 = S1 so that the linear transformation defined by K is indeed the identity transformation.
M >
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M >
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M >
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M >
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