Model-Independent Properties of the B-Meson Distribution Amplitude

Abstract

The operator product expansion is used to obtain model-independent predictions for the first two moments of the renormalized B-meson light-cone distribution amplitude phi_+(omega,mu), defined with a cutoff omega<Lambda_UV. The leading hadronic power corrections are given in terms of the parameter Lambda(bar)=m_B-m_b. From the cutoff dependence of the zeroth moment an analytical expression for the asymptotic behavior of the distribution amplitude is derived, which exhibits a negative radiation tail for omega>>mu. By solving the evolution equation for the distribution amplitude, an integral representation for phi_+(omega,mu) is obtained in terms an initial function phi_+(omega,mu_0) defined at a lower renormalization scale. A realistic model of the B-meson light-cone distribution amplitude is proposed, which satisfies the moment relations and has the correct asymptotic behavior. This model provides an estimate for the first inverse moment and the associated parameter lambda_B.Comment: 8 pages, 5 figures; problem in Figure 4 fixed, references updated; version to appear in Phys. Rev.