Duplančić, Goran; Melić, Blaženka
(2008)
B,B(s)> K form factors: An update of lightcone sum rule results.
Physical Review D, 78
(5).
054015105401512.
ISSN 15507998
Abstract
We present an improved QCD lightcone sum rule (LCSR) calculation of the B > K and B(s) > 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 hardscattering 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(0.04)(+0.05), f(BsK)(+)(0) = 0.30(0.03)(+0.04) and f(BK)(T)(0) = 0.30 +/ 0.05. By comparing among 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(B pi)(+)(0) = 1.38(0.10)(+0.11), f(BsK)(+)(0)/f(B pi)(+)(0) = 1.15(0.09)(+0.17), f(BK)(T)(0)/f(B pi)(T)(0) = 1.49(0.06)(+0.18), and f(BsK)(T)(0)/f(B pi)(T)(0) = 1.17(0.11)(+0.15).
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