The Joyce Theater celebrates the diversity of ballet with a two-week buffet of companies and choreographers who are molding the form in interesting ways. The Canadian choreographer Joshua Beamish, fresh off a collaboration with Wendy Whelan in her "Restless Creature" project, presents an evening that includes a duet for two Royal Ballet dancers and an ensemble work for 10 members of American Ballet Theater (Tuesday and Wednesday). On Thursday and next Friday, the Washington-based Chamber Dance Project presents four New York premieres, all set to live music.