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arXiv · 0706.1726

High Precision determination of the pi, K, D and D_s decay constants from lattice QCD

E. Follana·C. T. H. Davies·G. P. Lepage·J. Shigemitsu
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Abstract

We determine $D$ and $D_s$ decay constants from lattice QCD with 2% errors, 4 times better than experiment and previous theory: $f_{D_s}$ = 241(3) MeV, $f_D$ = 207(4) MeV and $f_{D_s}/f_D$ = 1.164(11). We also obtain $f_K/f_π$ = 1.189(7) and $(f_{D_s}/f_D)/(f_K/f_π)$ = 0.979(11). Combining with experiment gives $V_{us}$=0.2262(14) and $V_{cs}/V_{cd}$ of 4.43(41). We use a highly improved quark discretization on MILC gluon fields that include realistic sea quarks fixing the $u/d, s$ and $c$ masses from the $π$, $K$, and $η_c$ meson masses. This allows a stringent test against experiment for $D$ and $D_s$ masses for the first time (to within 7 MeV).

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E. Follana, C. T. H. Davies, G. P. Lepage, J. Shigemitsu. 2008-03-28. High Precision determination of the pi, K, D and D_s decay constants from lattice QCD. https://doi.org/10.1103/physrevlett.100.062002

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