11 research outputs found
Anomalies in Quantum Mechanics: the 1/r^2 Potential
An anomaly is said to occur when a symmetry that is valid classically becomes
broken as a result of quantization. Although most manifestations of this
phenomenon are in the context of quantum field theory, there are at least two
cases in quantum mechanics--the two dimensional delta function interaction and
the 1/r^2 potential. The former has been treated in this journal; in this
article we discuss the physics of the latter together with experimental
consequences.Comment: 16 page latex file; to be published in Am. J. Phy
Induced pseudoscalar coupling of the proton weak interaction
The induced pseudoscalar coupling is the least well known of the weak
coupling constants of the proton's charged--current interaction. Its size is
dictated by chiral symmetry arguments, and its measurement represents an
important test of quantum chromodynamics at low energies. During the past
decade a large body of new data relevant to the coupling has been
accumulated. This data includes measurements of radiative and non radiative
muon capture on targets ranging from hydrogen and few--nucleon systems to
complex nuclei. Herein the authors review the theoretical underpinnings of
, the experimental studies of , and the procedures and uncertainties
in extracting the coupling from data. Current puzzles are highlighted and
future opportunities are discussed.Comment: 58 pages, Latex, Revtex4, prepared for Reviews of Modern Physic