Theoretical aspects of neutral particle searches in high-energy channeling

Motivated mainly by yet unexplained data from heavy ion collisions, various attempts have been recently made to search for new light, short-lived neutral particles. Channeling of very high energy electrons can provide new ways to search for particles whose peculiar properties require for their production the presence of strong fields, such as particles with internal structure. We also discuss the possibility of enhancing the rate of Higgs boson production at high energy electron linear colliders by crystal channeling. (author)