Asymptotic normalization coefficients from ab initio calculations

Nollett, Kenneth M.; Wiringa, R. B.

doi:10.48550/arxiv.1102.1787

Cited by 4 publications

(19 citation statements)

References 30 publications

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“…[11,12]. First, we infer parameters of our leading-order (LO) EFT using binding energies and S-wave scattering lengths taken from experiment and ab initio ANCs calculated by the variational Monte Carlo (VMC) method [59] with realistic two-and three-nucleon interactions. This explains the title of this article.…”

Section: Differences From Previous Calculationsmentioning

confidence: 99%

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Marrying {\it ab initio} calculations and Halo-EFT: the case of ${}^7{\rm Li} + n \rightarrow {}^8{\rm Li} + γ$

Zhang,

Nollett,

Phillips

2013

Preprint

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We report a leading-order calculation of radiative 7 Li neutron captures to both the ground and first excited state of 8 Li in the framework of a low-energy effective field theory (Halo-EFT). Each of the possible final states is treated as a shallow bound state composed of both n + 7 Li and n + 7 Li * (core excitation) configurations. The ab initio variational Monte Carlo method is used to compute the asymptotic normalization coefficients of these bound states, which are then used to fix couplings in our EFT. We calculate the total and partial cross sections in the radiative capture process using this calibrated EFT. Fair agreement with measured total cross sections is achieved and excellent agreement with the measured branching ratio between the two final states is found. In contrast,a previous Halo-EFT calculation [G. Rupak and R. Higa, Phys. Rev. Lett 106, 222501 (2011)] assumes that the n-7 Li couplings in different spin channels are equal, fits the P -wave "effectiverange" parameter to the threshold cross section for 7 Li + n → 8 Li + γ, and assumes the core excitation is at high enough energy scale that it can be integrated out.

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Section: Differences From Previous Calculationsmentioning

confidence: 99%

“…In the "Nollett" ANCs, the 7 Li + n ANCs can be found Ref. [59], while 7 Li * + n ANCs are computed by the same methods in this study. The measured 7 Li + n ANCs are from Ref.…”

Section: An Example Of a Shallow P -Wave Bound Statementioning

confidence: 99%

Marrying {\it ab initio} calculations and Halo-EFT: the case of ${}^7{\rm Li} + n \rightarrow {}^8{\rm Li} + γ$

Zhang,

Nollett,

Phillips

2013

Preprint

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“…Much of a nucleon-level reaction calculation amounts to an indirect treatment of the collective motion of clusters through and around Coulomb and centrifugal barriers, so Halo EFT can profitably be combined with ab initio calculations. We extract asymptotic normalization coefficients (ANCs) from ab initio eight-body calculations [4,15], combine them with p- 7 Be scattering lengths from both experiment [16] and theory [4], and perform a predictive Halo EFT computation of 7 Be(p, γ) 8 B. This extends Ref.…”

mentioning

confidence: 99%

“…The s-wave scattering lengths, a ( 3 S1) and a ( 5 S2) , describe LO incoming channel multiple scattering (ICMS) effects. We thus obtain the S-factor including all initial channels: [15] and "Navratil" [4] are ab initio results, while "Tabacaru" [29] and "Angulo" [16] are from experiment. The units are fm −1/2 and fm for ANCs and scattering lengths respectively.…”

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Marrying ab initio calculations and Halo EFT: the case of ${}^7{\rm Be} + p \rightarrow {}^8{\rm B} + γ$

Zhang,

Nollett,

Phillips

2014

Preprint

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We report a leading-order (LO) calculation of 7 Be(p, γ) 8 B in a low-energy effective field theory. 8 B is treated as a shallow proton+ 7 Be core and proton+ 7 Be * (core excitation) p-wave bound state. The couplings are fixed using measured binding energies and proton-7 Be s-wave scattering lengths, together with 8 B asymptotic normalization coefficients from ab initio calculations. We obtain a zero-energy S-factor of 18.2 ± 1.2 (ANC only) eV b. Given that this is a LO result it is consistent with the recommended value S(0) = 20.8 ± 1.6 eV b. Our computed S(E) compares favorably with experimental data on 7 Be(p, γ) 8 B for E < 0.4 MeV. We emphasize the important role of proton-7 Be scattering parameters in determining the energy dependence of S(E), and demonstrate that their present uncertainties significantly limit attempts to extrapolate these data to stellar energies.

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Ab initiocalculations of nuclear widths via an integral relation

Nollett

2012

Phys. Rev. C

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I describe the computation of energy widths of nuclear states using an integral over the interaction region of ab initio variational Monte Carlo wave functions, and I present calculated widths for many states. I begin by presenting relations that connect certain short-range integrals to widths. I then present predicted widths for 5 ≤ A ≤ 9 nuclei, and I compare them against measured widths. They match the data more closely and with less ambiguity than estimates based on spectroscopic factors. I consider the consequences of my results for identification of observed states in 8 B, 9 He, and 9 Li. I also examine failures of the method and conclude that they generally involve broad states and variational wave functions that are not strongly peaked in the interaction region. After examining bound-state overlap functions computed from a similar integral relation, I conclude that overlap calculations can diagnose cases in which computed widths should not be trusted.

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Asymptotic normalization coefficients from ab initio calculations

Cited by 4 publications

References 30 publications

Marrying {\it ab initio} calculations and Halo-EFT: the case of ${}^7{\rm Li} + n \rightarrow {}^8{\rm Li} + γ$

Marrying {\it ab initio} calculations and Halo-EFT: the case of ${}^7{\rm Li} + n \rightarrow {}^8{\rm Li} + γ$

Marrying ab initio calculations and Halo EFT: the case of ${}^7{\rm Be} + p \rightarrow {}^8{\rm B} + γ$

Ab initiocalculations of nuclear widths via an integral relation

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