Methods of Alice physics

Abstract

Recently there has been a revival of interest in gauge theories with disconnected compact gauge groups. Gauge fields such that this disconnectedness has non-trivial physical effects are called Alice configurations. The question of the existence of such configurations is surprisingly intricate, and no complete theory is known. Here we give some simple techniques for establishing the existence of Alice configurations, with an emphasis on practical, readily verifiable conditions requiring a minimum of topological information on the base manifold and the gauge group.