Nuclear talks between Iran and six world powers resumed Tuesday in the Austrian capital, the start of a week of negotiations aimed at reaching a final agreement by the deadline next Monday. A final deal would end 11 years of diplomacy aimed at providing assurances that Iran wouldn’t be able move quickly to produce enough material for a nuclear bomb, in exchange for a phased lifting of tight international sanctions. Iran says its nuclear program is for purely peaceful, civilian purposes. Iranian Foreign Minister Javad Zarif held a lunch meeting Tuesday with the chair of the six-power group, former European Union foreign policy chief Catherine Ashton, and there were bilateral talks between the U.S. and Iranian teams.