Creation and evolution of magnetic helicity
نویسنده
چکیده
Projecting a non-Abelian SU(2) vacuum gauge field – a pure gauge constructed from the group element U – onto a fixed (electromagnetic) direction in isospace gives rise to a nontrivial magnetic field, with nonvanishing magnetic helicity, which coincides with the winding number of U . Although the helicity is not conserved under Maxwell (vacuum) evolution, it retains one-half its initial value at infinite time.
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