Six-body calculation of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>α</mml:mi></mml:math>-deuteron radiative capture cross section

We have computed the cross section for the process $d(\ensuremath{\alpha},\ensuremath{\gamma}{)}^{6}\mathrm{Li}$ at the low energies relevant for primordial nucleosynthesis and comparison with laboratory data. The final state is a six-body wave function generated by the variational Monte Carlo method from the Argonne ${v}_{18}$ and Urbana IX potentials, including improved treatment of large-particle-separation behavior. The initial state is built up from the $\ensuremath{\alpha}$-particle and deuteron ground-state solutions for these potentials, with phenomenological descriptions of scattering and cluster distortions. The dominant $E2$ cross section is in reasonable agreement with the laboratory data. Including center-of-energy and other small corrections, we obtain an $E1$ contribution which is larger than the measured contribution at 2 MeV by a factor of 7. We calculate explicitly the impulse-approximation $M1$ contribution, which is expected to be very small, and obtain a result consistent with zero. We find little reason to suspect that the cross section is large enough to produce significant ${}^{6}\mathrm{Li}$ in the big bang.

Перевод пока недоступен