It’s not every day you get to work with a Pulitzer Prize-winning librettist as a college student. It’s even less often that you share the same alma mater. When the sixth season of the CU New Opera Workshop, or CU NOW, kicks off this month, one of the opera professionals mentoring composition students knows Boulder well. Mark Campbell, a 1975 graduate of the Department of Theatre and Dance, is coming back to campus for the first time in 40 years.