  A class of previously unknown strong-interaction corrections is found to
enhance the rate of non-leptonic decays of the b quark by 5-8 percent. This
effect decreases the predicted fraction of semi-leptonic decays and brings it
into fair agreement with experimental results. As well as solving a
long-standing puzzle of measurements disagreeing with the Standard Model
prediction, our work suggests a way for future precise studies of non-leptonic
$b$ quark decays and their application to searching for "new physics."
