Relativistic Quantum Mechanics

This edition includes five new sections and a third appendix. Most other sections are expanded, in particular Sects. 5.2 and 5.6 on hyperfine interactions.
Section 3.8 offers an introduction to the important field of relativistic
quantum chemistry. In Sect. 5.7, the coupling of the anomalous magnetic
moment is needed for a relativistic treatment of the proton in hydrogen. It
generalizes a remarkable feature of leptonium, namely the non-hermiticity of
magnetic hyperfine interactions. In Appendix C, the explicit calculation of
the expectation value of an operator which is frequently approximated by
a delta-function confirms that the singularity of relativistic wave functions at
the origin is correct.
The other three new sections cover dominantly nonrelaticistic topics, in
particular the quark model. The coupling of three electron spins (Sect. 3.9)
provides also the basis for the three quark spins of baryons (Sect. 5.9). For less
than four particles, direct symmetry arguments are simpler than the representions of the permutation group which are normally used in the literature.
Another new topic of this edition is the confirmation of the E2-dependence
of atomic equations by the relativistic energy conservation in radiative atomic
transitions, according to the time-dependent perturbation theory of Sect. 5.4.
In the quark model, the E2-theorem applies not only to mesons, but also to
baryons as three-quark bound states. Unfortunately, the non-existence of free
quarks prevents a precise formulation of the phenomenological “constituent
quark model”, which remains the most challenging problem of relativistic
quantum mechanics.