We have computed the cross section for the process $d(\alpha ,\gamma {)}^6\mathrm{Li}$ 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 $\alpha$-particle and deuteron ground-state solutions for these potentials, with phenomenological descriptions of scattering and cluster distortions. The dominant $E2\mathrm{}$ cross section is in reasonable agreement with the laboratory data. Including center-of-energy and other small corrections, we obtain an $E1\mathrm{}$ contribution which is larger than the measured contribution at 2 MeV by a factor of 7. We calculate explicitly the impulse-approximation $M1\mathrm{}$ 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.

• Received 27 June 2000

DOI:https://doi.org/10.1103/PhysRevC.63.024003