Improved<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mi>e</mml:mi><mml:mo>,</mml:mo><mml:msup><mml:mi>e</mml:mi><mml:mrow><mml:mo>'</mml:mo></mml:mrow></mml:msup><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:math>response functions at intermediate momentum transfers: The<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mi mathvariant="normal">He</mml:mi><mml:mprescripts /><mm

A detailed study of the 4 He longitudinal response function RL(ω, q) is performed at different kinematics, with particular emphasis on the role of three-nucleon forces. The effects shown are the results of an ab initio calculation where the full four-body continuum dynamics is considered via the Lorentz integral transform method. The contributions of the various multipoles to the longitudinal response function are analyzed and integral properties of the response are discussed in addition. The Argonne V18 nucleon-nucleon interaction and two different three-nucleon force models (Urbana IX, Tucson-Melbourne ′ ) are used. At lower momentum transfer (q ≤ 200 MeV/c) three-nucleon forces play an important role. One even finds a dependence of RL on the three-nucleon force model itself with differences up to 10%. Thus a Rosenbluth separation of the inclusive electron scattering cross section of 4 He at low momentum transfer would be of high value in view of a discrimination between different three-nucleon force models.

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“…Ref. [27]). In the case of q = 250 MeV/c the experimental results are not sufficiently precise to draw a conclusion.…”

Section: Results Of the Lit Calculationmentioning

confidence: 99%

Search for three-nucleon force effects on the longitudinal response function ofHe4

et al. 2009

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“…An example will be presented for nd radiative capture, where the theoretical results are free from the uncertainty related to the omission of the Coulomb interaction. Also other approaches, as the Lorentz integral transform technique [30], have been applied to study the electromagnetic response of the trinucleon systems.…”

Section: Introductionmentioning

confidence: 99%

Electromagnetic structure of A=2 and 3 nuclei and the nuclear current operator

et al. 2005

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Different models for conserved two-and three-body electromagnetic currents are constructed from two-and three-nucleon interactions, using either meson-exchange mechanisms or minimal substitution in the momentum dependence of these interactions. The connection between these two different schemes is elucidated. A number of low-energy electronuclear observables, including (i) np radiative capture at thermal neutron energies and deuteron photodisintegration at low energies, (ii) nd and pd radiative capture reactions, and (iii) isoscalar and isovector magnetic form factors of 3 H and 3 He, are calculated in order to make a comparative study of these models for the current operator. The realistic Argonne v18 two-nucleon and Urbana IX or Tucson-Melbourne three-nucleon interactions are taken as a case study. For A=3 processes, the bound and continuum wave functions, both below and above deuteron breakup threshold, are obtained with the correlated hyperspherical-harmonics method. Three-body currents give small but significant contributions to some of the polarization observables in the 2 H(p, γ) 3 He process and the 2 H(n, γ) 3 H cross section at thermal neutron energies. It is shown that the use of a current which did not exactly satisfy current conservation with the two-and three-nucleon interactions in the Hamiltonian was responsible for some of the discrepancies reported in previous studies between the experimental and theoretical polarization observables in pd radiative capture.

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“…In [7] we already pointed that the ANB frame is preferable in case of quasi-elastic kinematics, since in this frame the nucleon momenta in initial and final states are only of the order of q/2, while in other frames one finds larger momenta, e.g., in the lab frame the knocked out nucleon has momentum q.…”

mentioning

confidence: 99%

“…On the other hand the proper treatment of relativistic kinematics leads to a slight increase of the peak heights, namely by 3.3%, 4.6%, and 6.1% at q = 500, 600, and 700 MeV/c, respectively. Such an increase improves the agreement with experimental data, however, the theoretical peak heights are still somewhat too low, but one should also take into account that some additional strength could come from currents involving the ∆-resonance.Our previous work [7] on frame dependence in R L (q, ω) compared ANB frame results with 4 those obtained in the lab and Breit frames all calculated using the two-fragment model. In Fig.…”

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Frame dependence ofHe3transverse(e,e′
Efros
¹
,
Leidemann
²
,
Orlandini
³

et al. 2011
Phys. Rev. C
Self Cite
9
2
16
0
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The transverse electron scattering response function of 3 He was recently studied by us in the quasi-elastic peak region for momentum transfers q between 500 and 700 MeV/c. Those results, obtained using the Active Nucleon Breit frame (ANB), are here supplemented by calculations in the laboratory, Breit and ANB frames using the two-fragment model discussed in our earlier work on the frame dependence of the the longitudinal response function R L (q, ω). We find relatively frame independent results and good agreement with experiment especially for the lower momentum transfers. This agreement occurs when we neglect an ω-dependent piece of the one-body current relativistic correction. An inclusion of this term leads however to a rather pronounced frame dependence at q = 700 MeV/c. A discussion of this term is given here. This report also includes a correction to our previous ANB results for R T (q, ω).PACS numbers: 25.30.Fj, 21.30 showed that the ANB frame appeared to diminish the effects of using non-relativistic nuclear dynamics. In addition, a two-fragment model was introduced which was found to significantly reduce frame dependence. In that model one assumes a quasi-elastic knock-out of a nucleon such that the residual nucleus remains in its lowest energy state. The relative momentum of the two fragments is determined in a relativistically correct way and the energy that is used as input to the non-relativistic calculation is obtained from that momentum by the usual non-relativistic relation. Considering for example the lab system, the quasielastically knocked out nucleon has momentum q, thus a difference between non-relativistic and relativistic kinetic energies ofTaking for example q = 700 MeV/c one has ∆T 1b = 29 MeV. This relativistic effect is automatically taken into account in the two-fragment model. It is important to state that this model only fixes a kinematical input while the full three-nucleon dynamics is still treated completely via the LIT technique. Thus a comparison of calculations done in the ANB frame with those done in any other frame (including the ANB frame) but with the two-fragment model provides some indication of uncertainties due to non-covariance.In dealing with the transverse response function of 3 He near the quasi-elastic peak where the energy-momentum of the virtual photon is absorbed predominantly by the single ejected nucleon one can again adopt the two-fragment model. Compared to the longitudinal response function there is however a slight difference in applying the two-fragment model to the transverse response. For the former we did not include a two-body charge operator, while for the latter we do consider, as mentioned above, an MEC. It is not evident that such a two-body current should be taken into account in the two-fragment model, since it violates the assumption of a quasi-elastic knock-out. Instead one may assume the following scenario (lab-system): initially two nucleons have opposite and equal momenta p and −p while the 2 third nucleon is at rest. If the photo...

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Improved(e,e')response functions at intermediate momentum transfers: TheHe

Cited by 37 publications

References 17 publications

Search for three-nucleon force effects on the longitudinal response function ofHe4

Search for three-nucleon force effects on the longitudinal response function ofHe4

Electromagnetic structure of A=2 and 3 nuclei and the nuclear current operator

Frame dependence ofHe3transverse(e,e′
Efros
¹
,
Leidemann
²
,
Orlandini
³

et al. 2011
Phys. Rev. C
Self Cite
9
2
16
0
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Improved(e,e')response functions at intermediate momentum transfers: TheHe

Cited by 37 publications

References 17 publications

Search for three-nucleon force effects on the longitudinal response function ofHe4

Search for three-nucleon force effects on the longitudinal response function ofHe4

Electromagnetic structure of A=2 and 3 nuclei and the nuclear current operator

Frame dependence ofHe3transverse(e,e′Efros1, Leidemann2, Orlandini3 et al. 2011Phys. Rev. CSelf Cite92160View full textAdd to dashboardCite

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Frame dependence ofHe3transverse(e,e′
Efros
¹
,
Leidemann
²
,
Orlandini
³

et al. 2011
Phys. Rev. C
Self Cite
9
2
16
0
View full text Add to dashboard Cite