We present the first lattice QCD estimate of the form factor f(+)(0), which is the key theoretical ingredient to extract \V-us\ from K-l3 decays. Our result, f(+)(K0pi-) (0) = 0.960 +/- 0.005(stat) +/- 0.007(syst), is in good agreement with the model estimate by Leutwyler and Roos and with the recent QCD sum rule estimate. After combining recent experimental results with our value for f(+)(K0pi-) (0), we could verify the unitarity of the first row of the CKM matrix, namely \V-us\(2)+ \V-ud\(2) + \V-ub\(2) = 0.9997(14). To make our estimate fully model independent we need to remove the quenched approximation and use ever lower quark masses (keeping, however, finite volume effects under control).
Becirevic, D., Isidori, G., Lubicz, V., Martinelli, G., Mescia, F., Simula, S., et al. (2005). The K ->pi vector form factor at zero momentum transfer on the lattice. In LATTICE 2004. Proceedings of the XXIInd International Symposium on Lattice Field Theory (pp.387-389) [10.1016/j.nuclphysbps.2004.11.247].
The K ->pi vector form factor at zero momentum transfer on the lattice
LUBICZ, Vittorio;TARANTINO, CECILIA;
2005-01-01
Abstract
We present the first lattice QCD estimate of the form factor f(+)(0), which is the key theoretical ingredient to extract \V-us\ from K-l3 decays. Our result, f(+)(K0pi-) (0) = 0.960 +/- 0.005(stat) +/- 0.007(syst), is in good agreement with the model estimate by Leutwyler and Roos and with the recent QCD sum rule estimate. After combining recent experimental results with our value for f(+)(K0pi-) (0), we could verify the unitarity of the first row of the CKM matrix, namely \V-us\(2)+ \V-ud\(2) + \V-ub\(2) = 0.9997(14). To make our estimate fully model independent we need to remove the quenched approximation and use ever lower quark masses (keeping, however, finite volume effects under control).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
