Electric dipole polarizabilities of hydrogen and helium isotopes

Stetcu, I.; Quaglioni, Sofia; Friar, J. L.; Hayes, A. C.; Navrátil, Petr

doi:10.1103/physrevc.79.064001

Cited by 28 publications

(42 citation statements)

References 57 publications

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“…The lines with scatter-symbols are the results from the LIT-CCSD method obtained for different values of the frequency Ω of the harmonic oscillator basis used to expand the potential. As expected, the polarizability is independent of the oscillator frequency as one increases N max , and converges rapidly to a value α D = 0.0815 fm 3 , which compares fairly well with the EIHH [9] result of α D = 0.0831 fm 3 and α D = 0.0822(5) fm 3 obtained using the no-coreshell-model with the same interaction [17]. Moreover, the convergence with respect to the number of Lanczos coefficients used in Eq.…”

Section: Benchmark In 4 Hesupporting

confidence: 86%

Electric dipole polarizability: from few- to many-body systems

Miorelli

Bacca

Barnea

et al. 2016

EPJ Web of Conferences

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Abstract. We review the Lorentz integral transform coupled-cluster method for the calculation of the electric dipole polarizability. We benchmark our results with exact hyperspherical harmonics calculations for 4 He and then we move to a heavier nucleus studying 16 O. We observe that the implemented chiral nucleon-nucleon interaction at next-to-next-to-next-to-leading order underestimates the electric dipole polarizability.

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Section: Benchmark In 4 Hesupporting

confidence: 86%

Electric dipole polarizability: from few- to many-body systems

Miorelli

Bacca

Barnea

et al. 2016

EPJ Web of Conferences

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“…There is more to physics than energy spectra however. For instance, we want to accurately quantify electric dipole transitions which lead to important observables that are difficult to measure: e.g., the polarization of a nucleus [27]; or the radiative capture 7 Be(p, γ) 8 B, crucial to understanding the neutrino signature of our sun [1,28]. When using SRG-evolved Hamiltonians, for consistency one should also evolve any other operator,…”

mentioning

confidence: 99%

“…We choose the total dipole strength because it is used to compute important quantities such as photo-absorption cross sections [31] and electric polarizabilities [27]. Our second investigation focuses on operator renormalization as a function of range, following a prescription similar to that of Ref.…”

mentioning

confidence: 99%

Operator evolution forab initiotheory of light nuclei

et al. 2014

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The past two decades have seen a revolution in ab initio calculations of nuclear properties. One key element has been the development of a rigorous effective interaction theory, applying unitary transformations to soften the nuclear Hamiltonian and hence accelerate the convergence as a function of the model space size. For consistency, however, one ought to apply the same transformation to other operators when calculating transitions and mean values from the eigenstates of the renormalized Hamiltonian. Working in a translationally-invariant harmonic oscillator basis for the twoand three-nucleon systems, we evolve the Hamiltonian, square-radius and total dipole strength operators by the similarity renormalization group (SRG). The inclusion of up to three-body matrix elements in the 4 He nucleus all but completely restores the invariance of the expectation values under the transformation. We also consider a Gaussian operator with adjustable range and find at short ranges an increased contribution from such induced three-body terms. . Of particular importance is the need to include ab initio three-body forces, for example, in correctly describing nuclear binding energies and spectra, especially the ground state spin of p-shell nuclei [5], the lifetime of 14 C [3], and the location of the neutron drip line for oxygen isotopes [6].These breakthrough discoveries have been driven by advances in computing, in effective field theory [7][8][9][10], in techniques for the solution of the nuclear many-body problem, such as the no-core shell model (NCSM) [11][12][13], and in modern effective interaction theory [14,15]. The latter takes the form of unitary transformations chosen to reduce the coupling between low-and highmomentum states, which arises from the bare nuclear interaction's "hard core" and leads to slow convergence in the size of the model space.Here we focus on the similarity renormalization group (SRG) [16,17], which has been successful when computing nuclear properties for a variety of nuclei [14,15,[18][19][20][21][22][23]. Independently developed by Glazek and Wilson [24] and Wegner [25], the SRG is a series of unitary transformations on the Hamiltonian,whereÛ s labels the sequence of transformations starting with the initial Hamiltonian at s = 0. This can be rewritten as a flow equation in s and an antihermitian generator,The generator is commonly chosen to be [T ,Ĥ s ], wherê T is the kinetic energy operator. This drives the Hamiltonian towards diagonal form in momentum space, thus weakening the coupling between low-and highmomentum states, though other generators have also been successful [26]. Rather than use the flow parameter, s, it is common to use λ = s −1/4 , to keep track of the sequence of Hamiltonians [19]; note that as λ decreases, the Hamiltonian will undergo more evolution.While formally the transformed Hamiltonian should be independent of the unitary transformation and specifically of the SRG flow parameter, the evolution induces higher-order terms, up to A-body, into the Hamiltonian. Previous ...

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“…Also shown in the figure as a dotted line is the evaluation of Ref. [34] based on a LS renormalization of the N 3 LO NN plus N 2 LO 3N interactions and bare dipole operator.…”

Section: Srg Resolution Scale Dependencementioning

confidence: 99%

“…An ab initio investigation of both the photoabsorption cross section [33] and the electric polarizability [34] of the 4 He nucleus based on chiral N N + 3N interactions had already been accomplished in the past using LS effective interactions at the three-body cluster level [35,36], albeit without renormalization of the electric dipole operator. The primary purpose of the present work is to use these observables as testing grounds to explore the performance and consistency of the SRG approach.…”

Section: Introductionmentioning

confidence: 99%

Operator evolution forab initioelectric dipole transitions ofHe4

et al. 2015

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A goal of nuclear theory is to make quantitative predictions of low-energy nuclear observables starting from accurate microscopic internucleon forces. A major element of such an effort is applying unitary transformations to soften the nuclear Hamiltonian and hence accelerate the convergence of ab initio calculations as a function of the model space size. The consistent simultaneous transformation of external operators, however, has been overlooked in applications of the theory, particularly for nonscalar transitions. We study the evolution of the electric dipole operator in the framework of the similarity renormalization group method and apply the renormalized matrix elements to the calculation of the 4 He total photoabsorption cross section and electric dipole polarizability. All observables are calculated within the ab initio no-core shell model. We find that, although seemingly small, the effects of evolved operators on the photoabsorption cross section are comparable in magnitude to the correction produced by including the chiral three-nucleon force and cannot be neglected.

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Electric dipole polarizabilities of hydrogen and helium isotopes

Cited by 28 publications

References 57 publications

Electric dipole polarizability: from few- to many-body systems

Electric dipole polarizability: from few- to many-body systems

Operator evolution forab initiotheory of light nuclei

Operator evolution forab initioelectric dipole transitions ofHe4

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