Semileptonic form factors D → π, K and B → π, K from a fine lattice

Deutsches Elektronen-Synchrotron DESY 22603 Hamburg Germany
European Physical Journal A (Impact Factor: 2.74). 01/2009; 43(1). DOI: 10.1140/epja/i2009-10893-3
Source: arXiv


We extract the form factors relevant for semileptonic decays of D and B mesons from a relativistic computation on a fine lattice in the quenched approximation. The lattice spacing is a = 0.04 fm (corresponding to a
-1 = 4.97 GeV), which allows us to run very close to the physical B meson mass, and to reduce the systematic errors associated with the extrapolation in terms of a heavy-quark expansion. For decays of D and Ds mesons, our results for the physical form factors at \(\ensuremath q^2 = 0\) are as follows: \(\ensuremath f_+^{D\rightarrow\pi}(0) = 0.74(6)(4)\) , \(\ensuremath f_+^{D \rightarrow K}(0) = 0.78(5)(4)\) and \(\ensuremath f_+^{D_s \rightarrow K} (0) = 0.68(4)(3)\) . Similarly, for B and Bs we find \(\ensuremath f_+^{B\rightarrow\pi}(0) = 0.27(7)(5)\) , \(\ensuremath f_+^{B\rightarrow K} (0) = 0.32(6)(6)\) and \(\ensuremath f_+^{B_s\rightarrow K}(0) = 0.23(5)(4)\) . We compare our results with other quenched and unquenched lattice calculations, as well as with light-cone sum rule predictions, finding good agreement.

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