出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：We compute the matrix elements of the electromagnetic (EM) operator between kaon and pion states, using lattice QCD with maximally twisted-mass fermions and two flavors of dynamical quarks (Nf = 2). The EM operator is renormalized non-perturbatively in the RI’/MOM scheme and our simulations cover pion masses as light as 260MeV and three values of the lattice spacing, ranging from 0.07 up to 0.1 fm. At the physical point our preliminary result for the K !p tensor form factor at zero-momentum transfer is f Kp T (0) = 0.42(2stat), which differs significantly from the old quenched result f Kp T (0) = 0.78(6) obtained by the SPQcdR Collaboration [1] with pion masses above 500 MeV. We investigate the source of this difference and conclude that it is mainly related to the chiral extrapolation of the quenched data. For the case of the tensor charge of the pion we obtain the preliminary value f pp T (0) = 0.200(14stat), which can be compared with the result f pp T (0) = 0.216(34) obtained at Nf = 2 by the QCDSF Collaboration [2] using higher pion masses.
