出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：We present a study of D→K, ln semileptonic decays on the lattice which employs the HISQ action for both the charm and the light quarks. We work with MILC unquenched Nf = 2+1 lattices and determine the scalar form factor f0(q2). This form factor is obtained from a scalar current matrix element that does not require any operator matching. We find f D→K 0 (0) ≡ f D→K + (0) = 0.747(19) in the chiral plus continuum limit and hereby improve the theory error on this quantity by a factor of ∼4 compared to previous lattice determinations. Combining the new theory result with recent experimental measurements of the product f D→K + (0) ∗ |Vcs| from BaBar and CLEO-c leads to a very precise direct determination of the CKM matrix element |Vcs|, |Vcs| = 0.961(11)(24), where the first error comes from experiment and the second is the lattice QCD theory error.
