We report measurements of the decays B -→Ds(*)+K -ℓ -ν ̄ℓ in a data sample containing 657×106BB̄ pairs collected with the Belle detector at the KEKB asymmetric-energy e +e - collider. We observe a signal with a significance of 6σ for the combined D s and Ds* modes and find the first evidence of the B -→Ds+K -ℓ -ν ̄ℓ decay with a significance of 3.4σ. We measure the following branching fractions: B(B -→Ds+K -ℓ -ν ̄ℓ)=(0.30±0.09(stat)-0.08+0.11(syst)) ×10 -3 and B(B -→Ds(*)+K -ℓ -ν ̄ℓ)=(0.59±0.12(stat) ±0.15(syst))×10 -3 and set an upper limit B(B -→Ds*+K -ℓ -ν ̄ℓ)<0.56×10 -3 at the 90% confidence level. We also present the first measurement of the Ds+K - invariant mass distribution in these decays, which is dominated by a prominent peak around 2.6GeV/c2.
|Journal||Physical Review D - Particles, Fields, Gravitation and Cosmology|
|Publication status||Published - 2012 Oct 23|
Bibliographical noteFunding Information:
The author wishes to thank Cynthia Garcia, Grace Kuo. and, especially. Jeff Griffith. for assistance with the bibliography. Kathy Brill and Sandy Ellithorpe provided invaluable secretarial assistance. The author was supported by grants from the Muscular Dystrophy Association and the National Institutes of Health (NS 19525) and an N.S.F. Presidential Young Investigator Award during the course of this work.
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics
- Physics and Astronomy (miscellaneous)