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Single-Particle Electrodynamics - Assassination Science

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efore neutral particles were discovered, and its use for such particles is messy<br />

and contrived; thus, we shall use the results of (D.15), (D.16) and (D.19),<br />

namely,<br />

M µν ≡ 2mµ<br />

q<br />

˜Σ µν ≡ 2mµ<br />

q<br />

ε µναβ U α Σ β ,<br />

(D.20)<br />

to replace Kolsrud and Leer’s M αβ wherever it appears in favour of µ, U α<br />

and Σ α .<br />

D.6 Verification of the retarded fields<br />

We can now complete the translation of the Cohn–Wiebe field expressions,<br />

(D.7), into the conventions and notation of this thesis.<br />

Concentrating first on the fields generated by the electric charge, we have,<br />

from (D.7) and the relations of Section D.4,<br />

F ′ = qϕ 2 (1 − ˙χ)ζ ∧U + qϕζ ∧ ˙U.<br />

This agrees with the result (5.28) of Chapter 5, and justifies the identification<br />

(D.13).<br />

Turning now to the dipole fields, we need to convert the magnetic dipole<br />

expressions of Cohn and Wiebe into the equivalent expressions for an electric<br />

dipole, since we primarily focussed on the electric case in Chapter 5. To do so,<br />

we need only note that the electric field per electric dipole unit E/d generated<br />

by an electric dipole d α is equal to the magnetic field per magnetic dipole<br />

unit B/µ generated by a magnetic dipole µ α (excluding the extra Maxwell<br />

term for the magnetic dipole—but Cohn and Wiebe do not consider the<br />

worldline fields). Since a duality transformation F αβ → ˜F αβ induces the<br />

transformations E → B, B → −E, we need to take the negative of the dual<br />

of the magnetic dipole part of the Cohn–Wiebe fields (D.7) in order to get<br />

the equivalent electric dipole fields. In other words, we need to compute<br />

×<br />

Fn d ≡ − 1 F (−n) ,<br />

2<br />

(D.21)<br />

386

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