Federal Reserve policymakers appeared deeply divided on Saturday over how seriously problems in the world economy will effect the U.S., a fracture that may be difficult for Fed Chair Janet Yellen to mend as she guides the central bank’s debate over whether to hike interest rates. Bullard, who does not have a vote this year on the Fed’s main policy-setting committee, said he would have joined Richmond Fed President Jeffrey Lacker’s dissent, and worried the central bank had paid too much attention to recent financial market gyrations.