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Semileptonic form factors D $ \rightarrow$ $ \pi$ , K and B $ \rightarrow$ $ \pi$ , K from a fine lattice

Al-Haydari, A. ; Ali Khan, A. ; Braun, V. ; Collins, S. ; Göckeler, M. ; Lacagnina, G. ; Panero, M. ; Schäfer, A. ; Schierholz, G.

In: The European Physical Journal A, 2010, vol. 43, no. 1, p. 107-120

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    Title
    • Semileptonic form factors D $ \rightarrow$ $ \pi$ , K and B $ \rightarrow$ $ \pi$ , K from a fine lattice
    Author
    • Al-Haydari, A.. Department of Physics, Faculty of Science, Taiz University, Taiz, Yemen
    • Ali Khan, A.. Department of Physics, Faculty of Science, Taiz University, Taiz, Yemen
    • Braun, V.. Institute for Theoretical Physics, University of Regensburg, 93040, Regensburg, Germany
    • Collins, S.. Institute for Theoretical Physics, University of Regensburg, 93040, Regensburg, Germany
    • Göckeler, M.. Institute for Theoretical Physics, University of Regensburg, 93040, Regensburg, Germany
    • Lacagnina, G.. INFN, Sezione di Milano, 20133, Milano, Italy
    • Panero, M.. Institute for Theoretical Physics, University of Regensburg, 93040, Regensburg, Germany
    • Schäfer, A.. Institute for Theoretical Physics, University of Regensburg, 93040, Regensburg, Germany
    • Schierholz, G.. Institute for Theoretical Physics, University of Regensburg, 93040, Regensburg, Germany
    Document Type
    • Postprint
    Classification
    • Engineering
    OAI-PMH Identifier
    • oai:doc.rero.ch:314958
    Summary
    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