Decays with Perturbative QCD Approach

Table 2

The numerical values of input parameters.

The Wolfenstein parameters
[1],	[1],
Mass, decay constant, and Gegenbauer moments
GeV [1],	MeV [1],
GeV [1],	MeV [1],
MeV [14],	MeV [15],
(1 GeV) [16],	MeV [17],
(1 GeV) [16],	MeV [17],
(1 GeV) [16],	MeV [17].

The decay constant cannot be extracted from the experimental data because of no measurement on weak decay at the present time. Theoretically, the value of has been estimated, for example, in [18], with the QCD sum rules. From Table of [18], one can see that the value of is model-dependent. In our calculation, we will take the latest value given by the lattice QCD approach [15] just to offer an order of magnitude estimation on branching ratio for decays.