Elastic $\alpha$-${}^{12}$C scattering at low energies with the sharp resonant $0_3^{+}$ state of ${}^{16}$O

Abstract

An inclusion of sharp resonant $0_3^{+}$ state of ${}^{16}$O and first excited $2_1^{+}$ state of ${}^{12}$C in a study of $s$-wave elastic $\alpha$-${}^{12}$C scattering at low energies is investigated in an effective Lagrangian approach. The elastic scattering amplitude is parted into two; one is for the sharp resonant $0_3^{+}$ state of ${}^{16}$O parameterized by Breit-Wigner formula, and the other is for a non-resonant part of the amplitude parameterized by effective range expansion. In the non-resonant part of the amplitude, a contribution from the $2_1^{+}$ state of ${}^{12}$C is included. We discuss a large correlation between a coupling for the $2_1^{+}$ state of ${}^{12}$C and an effective range parameter $Q_0$ as well as a necessity of inclusion of a vertex correction for the initial and final $\alpha$-${}^{12}$C states. After fixing parameters appearing in the amplitudes by using experimental data, we calculate asymptotic normalization coefficients for ground $0_1^{+}$ state and first excited $0_2^{+}$ state of ${}^{16}$O and compare them to previous results found in literature.

Comments: 14 pages, 4 eps figures, version accepted for publication in Phys. Rev. C