Other recent research includes Blanchard, Cerutti, and Summers (2015) and Kiley (2015b). BIS central bankers’ speeches  common shocks or trends that cause economic conditions to be synchronized across economies. The sharp repeated declines in the price of oil have been a major common factor depressing headline inflation and are also likely feeding into low core inflation, although to a lesser extent.
5 As noted previously, these price declines have led headline inflation across the globe to behave quite similarly over this time period. Even so, most observers expect this source of convergence in inflationary outcomes to eventually fade and thereafter not affect monetary policy paths over the medium term.