Sign of the Static Electric Polarizability in Relativistic Quantum Theory

Abstract

The question of the sign of the static electric polarizability ${\ensuremath{\alpha}}_{E}$ of an elementary system is studied within the framework of relativistic quantum theory. It is emphasized that a high-energy assumption is necessary to derive ${\ensuremath{\alpha}}_{E}>0$. Thus, although available experimental information is consistent with this inequality, the discovery of a system for which ${\ensuremath{\alpha}}_{E}$ is negative does not appear to be excluded on the basis of general principles alone.