ИСТИНА

Asymptotic normalization coefficients (ANCs) are important nuclear characteristics. They determine cross sections of radiative capture processes at astrophysical energies [1]. Their knowledge is necessary for solving the inverse scattering problem. 6Li nucleus in the α+d channel is one of the most interesting systems for which it is important to know ANCs. The ANC values for this system determine the cross section of the radiative capture 4He(d,γ) 6Li, which is the only process of 6Li formation in the Big Bang model. The available data on the values of the ANCs Cl for the 6Li→ α+d channel are characterized by a large spread (l = 0, 2 is the channel orbital angular momentum). In the given work, the Cl values are found by analytic continuation in energy of the effective range expansion for dα scattering to the pole corresponding to the bound 6Li state. Both one- and two-channel [2] versions of the effective range expansion are employed. Several sets of scattering phases are used as an input: The phase-shift analysis made in [3] with neglect of the coupling of l=0 and l=2 channels, the results of Faddeev calculations neglecting the Coulomb interaction [4], and the phase-shift analysis made in [5] with account of the channel coupling. The calculations are performed with and without the preassigned (fixed) value of the 6Li binding energy ε. It follows from the numerical results obtained that the absolute values of Cl increase with increasing ε as well as with taking account of the Coulomb interaction. Account of the channel coupling affects only slightly the C0 value. On the other hand, account of that coupling is absolutely necessary to get the reliable C2 value. The ways of allowing for two- and three-body inelastic threshold phenomena within the effective range expansion formalism are discussed. The need for more accurate low-energy dα scattering data and the corresponding phase-shift analysis is emphasized.