They found that financial booms were especially harmful to certain industries. Bankers, they say, act in predictable ways. They tend to lend money to projects with assets that can be pledged as collateral, such as those in real estate or construction. This is understandable — bankers want to be able to seize assets if a borrower gets into trouble on a loan, and they prefer those assets to be tangible.

But these industries are also among the least productive, and that leaves fewer dollars for more promising research-and-development start-ups that may have only intangibles, such as knowledge and ideas, to offer a banker as collateral. Even though such start-ups have far more potential than projects backed by tangible collateral, they don’t attract the financing they need.

This is true during slow-growth economic times as well, but during boom times, so much money crowds into less productive sectors that the overall economy suffers.

“By draining resources from the real economy,” the authors wrote, “financial-sector growth becomes a drag on real growth.”

The impact is sizable.

“We find unambiguous evidence for very large effects of financial booms on industries that either have significant external financing needs or are R.&D.-intensive,” the authors concluded in their paper. Even in economies where finance is growing quickly, industries that require a lot of research and development trail the performance of other industries in economies where finance is experiencing slower growth, they found. In fact, that productivity growth appeared to be two percentage points lower per year. Two percentage points a year is an enormous difference.

Another pernicious element is at work, the authors said. When finance is ascendant in an economy, it attracts an inordinate number of highly skilled workers who might otherwise take their productivity and brains to nonfinancial industries.

I spoke with Professor Cecchetti last week about the paper. “When I was in college long ago, all my friends wanted to figure out how to cure cancer,” he said. “But by the 1990s, everyone wanted to become hedge fund managers. Do we want to have more hedge fund managers or more people trying to figure out how to solve our energy and environmental problems or otherwise improving our lives? That’s the way I think about the problem.”