We present new lattice results of the K ->pi l nu 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 K(l3) decays, leads to |V(us)|=0.2267(5)(exp)(20)(f+)(0). Using the PDG(2008) determinations of |V(ud)| and |V(ub)| our result implies for the unitarity relation |V(ud)|(2)+|V(us)|(2)+|V(ub)|(2)=1.0004(15). For the O(p(6)) term of the chiral expansion of f(+)(0) we get Delta f equivalent to f(+)(0)-1-f(2)=-0.0214(84).
Lubicz, V., Mescia, F., Simula, S., Tarantino, C. (2009). K ->pi l nu semileptonic form factors from two-flavor lattice QCD. PHYSICAL REVIEW D, PARTICLES, FIELDS, GRAVITATION, AND COSMOLOGY, 80(11) [10.1103/PhysRevD.80.111502].
K ->pi l nu semileptonic form factors from two-flavor lattice QCD
LUBICZ, Vittorio;TARANTINO, CECILIA
2009-01-01
Abstract
We present new lattice results of the K ->pi l nu 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 K(l3) decays, leads to |V(us)|=0.2267(5)(exp)(20)(f+)(0). Using the PDG(2008) determinations of |V(ud)| and |V(ub)| our result implies for the unitarity relation |V(ud)|(2)+|V(us)|(2)+|V(ub)|(2)=1.0004(15). For the O(p(6)) term of the chiral expansion of f(+)(0) we get Delta f equivalent to f(+)(0)-1-f(2)=-0.0214(84).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
