Arthur Bauernfeind was named chairman and CEO of Westfield Capital Management. He replaces company founder C. Michael Hazard, now vice chairman and director of Westfields parent company, Boston Private Financial Holdings, said spokesman Scott Emberley. Mr. Bauernfeind was chief investment officer at Westfield. William Muggia, senior portfolio manager, will replace Mr. Bauernfeind as CIO. Mr. Muggia and Steven Demirjian, senior portfolio manager, also were elected co-presidents; both will continue to manage assets. In addition, Karen DiGravio, CFO, was elected executive vice president.