In its continuing campaign to attract top scholars, UC Irvine has hired Harvard psychology professor R. Duncan Luce, as well as Dennis Aigner, the former chairman of the economics department of USC. They will join the Irvine faculty this fall. Aigner, credited with building USC’s economics department into one of the top 20 in the nation, will serve as dean of UC Irvine’s Graduate School of Management. Luce, 62, an internationally known mathematical theorist, will direct a new research institute at the School of Social Science intended to develop mathematical models to analyze and explain human behavior. With nearly $100 million in construction under way at Irvine this year, university officials are making “a concerted effort to reach out to this country’s higher-quality scholars to work with us during our growth,” said John Miltner, university vice chancellor.