<p>Local gauge invariance is a pivot of modern physics of elementary particles. Standard model of elementary particles is a non-abelian gauge theory with the gauge group <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(\varvec{G=SU(3)\otimes SU(2)\otimes U(1)}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi mathvariant="bold-italic">G</mi> <mo mathvariant="bold">=</mo> <mi mathvariant="bold-italic">S</mi> <mi mathvariant="bold-italic">U</mi> <mo mathvariant="bold" stretchy="false">(</mo> <mn mathvariant="bold">3</mn> <mo mathvariant="bold" stretchy="false">)</mo> <mo mathvariant="bold">⊗</mo> <mi mathvariant="bold-italic">S</mi> <mi mathvariant="bold-italic">U</mi> <mo mathvariant="bold" stretchy="false">(</mo> <mn mathvariant="bold">2</mn> <mo mathvariant="bold" stretchy="false">)</mo> <mo mathvariant="bold">⊗</mo> <mi mathvariant="bold-italic">U</mi> <mo mathvariant="bold" stretchy="false">(</mo> <mn mathvariant="bold">1</mn> <mo mathvariant="bold" stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation>, that is the theory is constructed to be invariant under a gauge transformation <InlineEquation ID="IEq2"> <EquationSource Format="TEX">\(\varvec{\psi (x) \rightarrow U(x) \psi (x)}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi mathvariant="bold-italic">ψ</mi> <mo mathvariant="bold" stretchy="false">(</mo> <mi mathvariant="bold-italic">x</mi> <mo mathvariant="bold" stretchy="false">)</mo> <mo mathvariant="bold">→</mo> <mi mathvariant="bold-italic">U</mi> <mo mathvariant="bold" stretchy="false">(</mo> <mi mathvariant="bold-italic">x</mi> <mo mathvariant="bold" stretchy="false">)</mo> <mi mathvariant="bold-italic">ψ</mi> <mo mathvariant="bold" stretchy="false">(</mo> <mi mathvariant="bold-italic">x</mi> <mo mathvariant="bold" stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation>, where <InlineEquation ID="IEq3"> <EquationSource Format="TEX">\(\varvec{U(x)}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi mathvariant="bold-italic">U</mi> <mo mathvariant="bold" stretchy="false">(</mo> <mi mathvariant="bold-italic">x</mi> <mo mathvariant="bold" stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> is a representation of <Emphasis Type="BoldItalic">G</Emphasis> acting on matter fields <InlineEquation ID="IEq4"> <EquationSource Format="TEX">\(\varvec{\psi (x)}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi mathvariant="bold-italic">ψ</mi> <mo mathvariant="bold" stretchy="false">(</mo> <mi mathvariant="bold-italic">x</mi> <mo mathvariant="bold" stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> at a point <InlineEquation ID="IEq5"> <EquationSource Format="TEX">\(\varvec{x\in \mathcal {M}}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi mathvariant="bold-italic">x</mi> <mo mathvariant="bold">∈</mo> <mi mathvariant="bold-script">M</mi> </mrow> </math></EquationSource> </InlineEquation> of some continuous differentiable manifold. The problem with extrapolation of gauge theories down to the Planck scales is that there is no continuous differentiable manifold in quantum gravity regime, and hence, neither the value of field at a point, nor a covariant derivative are defined in a usual way. We do such extrapolation assuming that our spacetime is a combinatorial spacetime, the points of which are the interaction vertices of matter fields. The vertices are connected to each other by matter particles. The gauge invariance then becomes a symmetry with respect to independent internal rotations of all fermion lines in the edges of the matter spin network graph. There is no need to introduce special gauge fields in this picture, since they are expressed in terms of fermion fields.</p>

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Matter Spin Networks and Gauge Invariance at Planck Scales

  • Mikhail Altaisky

摘要

Local gauge invariance is a pivot of modern physics of elementary particles. Standard model of elementary particles is a non-abelian gauge theory with the gauge group \(\varvec{G=SU(3)\otimes SU(2)\otimes U(1)}\) G = S U ( 3 ) S U ( 2 ) U ( 1 ) , that is the theory is constructed to be invariant under a gauge transformation \(\varvec{\psi (x) \rightarrow U(x) \psi (x)}\) ψ ( x ) U ( x ) ψ ( x ) , where \(\varvec{U(x)}\) U ( x ) is a representation of G acting on matter fields \(\varvec{\psi (x)}\) ψ ( x ) at a point \(\varvec{x\in \mathcal {M}}\) x M of some continuous differentiable manifold. The problem with extrapolation of gauge theories down to the Planck scales is that there is no continuous differentiable manifold in quantum gravity regime, and hence, neither the value of field at a point, nor a covariant derivative are defined in a usual way. We do such extrapolation assuming that our spacetime is a combinatorial spacetime, the points of which are the interaction vertices of matter fields. The vertices are connected to each other by matter particles. The gauge invariance then becomes a symmetry with respect to independent internal rotations of all fermion lines in the edges of the matter spin network graph. There is no need to introduce special gauge fields in this picture, since they are expressed in terms of fermion fields.