engleski

B, B(s) ---> K form factors: An Update of light-cone sum rule results

We present an improved QCD light-cone sum rule (LCSR) calculation of the B → K and Bs → K form factors by including SU(3)-symmetry breaking corrections. We use recently updated K meson distribution amplitudes which incorporate the complete SU(3)-breaking structure. By applying the method of direct integration in the complex plane, which is presented in detail, the analytical extraction of the imaginary parts of LCSR hard-scattering amplitudes becomes unnecessary and therefore the complexity of the calculation is greatly reduced. The values obtained for the relevant B(s) → K form factors are as follows: f+BK(0) = 0.36+0.05− 0.04, f+BsK(0)=0.30+0.04− 0.03, and fTBK(0) = 0.38± 0.05, fTBsK(0) = 0.30± 0.05. By comparing with the B → Pi form factors extracted recently by the same method, we find the following SU(3) violation among the B → light form factors: f+BK(0)/f+BPi(0) = 1.38+0.11− 0.10, f+BsK(0)/f+BPi(0) = 1.15+0.17− 0.09, fTBK(0)/fTBPi(0) = 1.49+0.18− 0.06, and fTBsK(0)/fTBPi(0) = 1.17+0.15− 0.11.

B decays; sum rules

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