We present a complete study of the associated production of the (eta _c) meson with light hadrons in (e^+e^-) collisions at the B-factory energy, which is demonstrated to be one of the best laboratories for testing the colour-octet (CO) mechanism. The colour-singlet contributions are evaluated up to (O(alpha ^2alpha _s^3)), while the CO ones are evaluated up to (O(alpha ^2alpha _s^2)). For the first time, the angular distribution of the (^1S_0^{[8]}) production is studied at QCD next-to-leading order. We find that the (^1S_0^{[8]}) channel dominates the total cross section, while the (^1P_1^{[8]}) one exhibits its importance in the angular distribution, which turns out to be downward going with respect to (mathrm {cos} heta ). This can be considered as the most distinct signal for the CO mechanism.
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