TD Ottawa Jazz Festival:Happenstance Quartet(noon, Rideau Centre),Sarah Neufeld(5 p.m., NAC Backstage), Arild Anderson Trio, with Tommy Smith, Paolo Vinaccia(7 p.m., NAC Backstage),Dan Brubeck Quartet(6:30 p.m., Confed. Park),Colin Stetson presents: Sorrow(NAC, 9 p.m.),Ben Caplan(7:30 p.