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arXiv · 0906.4728

K -> pion Semileptonic Form Factors from Two-Flavor Lattice QCD

V. Lubicz·F. Mescia·S. Simula·C. Tarantino
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Abstract

We present new lattice results of the K -> pion semileptonic form factors obtained from simulations with two flavors of dynamical twisted-mass fermions, using pion masses as light as 260 MeV. Our main result is f+(0) = 0.9560 (84), which, combined with the latest experimental data for Kl3 decays, leads to |V_{us}| = 0.2267 (5)_exp (20)_f+(0). Using the PDG(2008) determinations of |Vud| and |Vub| our result implies for the unitarity relation |Vud|**2 + |Vus|**2 + |Vub|**2 = 1.0004 (15). For the O(p**6) term of the chiral expansion of f+(0) we get Df = f+(0) - 1 - f2 = -0.0214 (84).

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V. Lubicz, F. Mescia, S. Simula, C. Tarantino. 2009-06-25. K -> pion Semileptonic Form Factors from Two-Flavor Lattice QCD. https://doi.org/10.1103/physrevd.80.111502

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