For the last couple of decades, the ultraconservatove jazz movement known to some as neoclassicism and to others as “The Cult of Wynton Marsalis” has had a profound influence on rising young musicians. But Marsalis’s influence seems to be slipping, as a new generation of jazzers raised on hip-hop and R&B comes of age. Some of the new breed feel that the neoclassicisists confuse history with tradition, and are eager to branch out into new realms of musical exploration.