Coupled-channel treatment of Li-7(n, gamma)Li-8 in effective field theory

Autor(es)

Higa, Renato ^[1] ; Premarathna, Pradeepa ^{[2, 3]} ; Rupak, Gautam ^{[2, 3]}

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Fis, R Matao 1371, BR-05508090 Sao Paulo, SP - Brazil

^[2] Mississippi State Univ, Ctr Computat Sci, Dept Phys & Astron, Mississippi State, MS 39762 - USA

^[3] Mississippi State Univ, Ctr Computat Sci, HPC2, Mississippi State, MS 39762 - USA

• Tipo de documento: Artigo Científico
• Fonte: EUROPEAN PHYSICAL JOURNAL A; v. 57, n. 9 SEP 2021.
• Citações Web of Science: 0

Resumo

The E1 contribution to the capture reaction Li-7(n, gamma)Li-8 is calculated at low energies. We employ a coupled-channel formalism to account for the 7Li(star) excited core contribution. We develop a halo effective field theory power counting where capture in the spin S = 2 channel is enhanced over the S = 1 channel. A next-to-leading order calculation is presented where the excited core contribution is shown to affect only the overall normalization of the cross section. The momentum dependence of the capture cross section, as a consequence, is the same in a theory with or without the excited 7Li(star) degree of freedom at this order of the calculation. The kinematical signature of the 7Li(star) core is negligible at momenta below 1 MeV and significant only beyond the 3(+) resonance energy, though still compatible with a next-to-next-to-leading order correction. We compare our formalism with a previous halo effective field theory calculation {[}Zhang et al., Phys. Rev. C 89, 024613 (2014)] that also treated the 7Li(star) core as an explicit degree of freedom. Our formal expressions and analysis disagree with this earlier work in several aspects. (AU)

• Processo FAPESP: 17/05660-0 - Estudos teóricos da estrutura e reações de núcleos exóticos e sistemas de muitos corpos
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