The American economy could experience painfully slow growth and stubbornly high unemployment for a decade or longer as a result of the 2007 collapse of the housing market and the economic turmoil that followed, according to an authority on the history of financial crises.

That finding, contained in a new paper by Carmen M. Reinhart, an economist at the University of Maryland, generated considerable debate during an annual policy symposium here, organized by the Federal Reserve Bank of Kansas City, which concluded on Saturday.