A boundary-state computation is performed to obtain derivative corrections to the Cherna€“Simons coupling between a e?‘?-brane and the RR gauge potential e???e?‘?-3. We work to quadratic order in the gauge ???eld strength e??1, but all orders in derivatives. In a certain limit, which requires the presence of a constant e??μ-???eld background, it is found that these corrections neatly sum up into the *2 product of (commutative) gauge ???elds. The result is in agreement with a recent prediction using noncommutativity
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