0 v 1 2 2 A ug 2 00 5 W - exchange / Annihilation amplitudes in LCSR - B 0 d → D − s K + as an example
نویسنده
چکیده
We evaluate the W-exchange diagram within the framework of light cone sum rules (LCSR), taking B0 d → D s K+ as an example. This decay mode, though proceeding via the W-exchange diagram only and therefore expected to be highly suppressed, has the branching ratio 3.2 × 10−5. We estimate the W-exchange amplitude within LCSR, including soft gluon corrections, to twist-3 accuracy and show that there is a fair agreement with the observed branching ratio. The calculation naturally brings out the features which suggest that such an amplitude is expected to be small in cases when both the final state mesons are light, without relying on any kind of an assumption. With minor changes, it is also possible to have a rough estimate of the exchange/annihilation type contributions to other processes like B → ππ, πK,KK.
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