arXiv:0906.4728·v1·High Energy Physics — Lattice
K -> pion Semileptonic Form Factors from Two-Flavor Lattice QCD
V. Lubicz🇮🇹 · F. Mescia🇪🇸 · S. Simula🇮🇹 · C. Tarantino (for the ETM Collaboration)🇮🇹
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).
Comments: 4 pages, 4 figures, 1 table, revtex