Il Nuovo Cimento A (1971-1996)

, Volume 111, Issue 1, pp 95–104 | Cite as

Semileptonic B-decay as a test of CKM unitarity

  • L. T. Handoko


I point out that B → Xq l+ l- decays (q = s, d) are sensitive probes of possible violation of CKM unitarity. I compute the decay rates and asymmetries in a minimal extension of the Standard Model containing an additional isosinglet charge (-1/3) quark, which leads to a deviation from CKM unitarity. It is shown that even for small mixing ratios |zqb/(Vtq*Vtb)|O(10-2), the contribution of the tree-levelZ-FCNC appearing in the model should change the rates and asymmetries significantly. Especially theCP asymmetry, A CP (B → Xs l+ l-), can be enhanced to be few percents, while in the standard model the size is less thanO(1023). On the other hand, A CP (B → Xs l+) is not altered so much. Constraints for the mixing ratios are extracted from the experiments of B→Xs ΰ for q = s and B0d-B0d mixing for q = d under the natural assumption that the couplings of the tree-level Zff are almost unity,i.e.zαα ∼ 1.

PACS 12.15.Hh

Determination of Kobayashi-Maskawa matrix elements 

PACS 12.60.Cn

Extensions of electroweak gauge sector 

PACS 13.20.He

Decays of bottom mesons 

PACS 13.30.Ce

Leptonic and semileptonic decays 


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Copyright information

© Società Italiana di Fisica 1998

Authors and Affiliations

  1. 1.Department of PhysicsHiroshima UniversityHigashi HiroshimaJapan

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