BOSTON — Several former U.S. governors will be gathering at the Harvard University School of Public Health to discuss the nation's ongoing opioid addiction crisis.The forum on Thursday will examine various long-term approaches for addiction treatment and the role state government has in developing and implementing treatment programs.The former governors participating include Republican Jim Douglas from Vermont and Democrats Steven Beshear from Kentucky; Ted Strickland from Ohio; Jack Markell from Delaware; and Kathleen Sebelius from Kansas.