Past exam of the mathematics course of the University of Cambridge 2009 iii Paper 49 2 ii Solution Created 2026-10-03 Updated 2026-10-14
The Derrick scaling of the Abelian Higgs energy must rescale the gauge potential as well as the Higgs field. SetThen andLet , and , with all integrals over the plane. Changing variables givesAt a static solution, . ConsequentlyThe covariant-gradient contribution is scale invariant, while the magnetic and potential terms balance. This is why the scalar-only nonexistence conclusion does not extend to the Abelian Higgs model.