The study is not the first to argue that the Fed's outlook for the economy, dubbed an "immaculate disinflation" by some observers, is unrealistic and will at some point force policymakers into hard choices about how much higher interest rates may need to rise in order to lower inflation and how steep a price they are willing to pay in terms of job losses. Some estimates have suggested the unemployment rate, currently at more than a five-decade low of 3.4%, may have to approach 7% for inflation to fall on a reasonable timetable