Halo and halo excitations

Abstract

A brief overview is given of the present status of our knowledge on halo states. The emphasis is put on general ideas and concepts. A discussion of what the central ingredients in the halo structure are is followed by a comparison between the established and proposed halo states. The various experimental probes of halos are reviewed. Particular attention is given to simple excitations built upon halo states including isobaric analogue states.