Try googling 'poles of world economy'. This term is standard economics-speak.

22 Jun 2009 ... “the mysterious other pole of the world economy”.
http://fabiusmaximus.wordpress.com/2009/06/22/china-3/

Poles of market growth?:Open questions about China, information

expected to ... IMF plan looks to bridge world's economic poles ...

These three economic poles dominate the global economy. According to World Bank data, North America produced 28.3% of global GNP in 1995, the EU 29.5% and ...

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Note added at 5 hrs (2011-01-20 16:09:26 GMT)
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And this IS an economics course so if there is correct technical term it should be used.

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Note added at 7 hrs (2011-01-20 17:31:20 GMT)
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More examples

"The paper undertakes a detailed examination of growth-pole strategies, an emphasis in regional economic planning during the 1960s which never lived up to its early promise. The initial concern is with the origins of the strategy, particularly the manner"

"India could be a new pole of global growth: WB President"

"Africa Emerging a Pole in Global Economy-World Bank"

"In addition to the poles of market and hierarchy, this continuum contains ... the linkages that emerge between places and processes in the world economy. ..."
(The Princeton Encyclopedia of the World Economy)

"Whether or not the international automobile industry is a growth pole in the world economy remains to be seen. If it is, the nature of its dominance may be ..."

"North America, a very different economic pole, has also seen its share of world output decline, but more modestly: from roughly 30 percent in 1960 to less ..."