Semirelativistic description of quasielastic neutrino reactions and superscaling in a continuum shell model

Amaro, J. E.; Bárbaro, M. B.; Caballero, J. A.; Donnelly, T. W.; Maieron, C.

doi:10.1103/physrevc.71.065501

Cited by 97 publications

(213 citation statements)

References 68 publications

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“…However, as shown in Ref. [13], the present SR model gives results that are very similar to the RMF, where the same potential is used for initial and final states and thus there is no orthogonality problem. This allows us to conclude that the nonorthogonality effects are very small.…”

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confidence: 80%

“…In this article we use the approach of Refs. [11,13] where a specific SR expansion of the electroweak single-nucleon current was used in a continuum shell-model description of electron and neutrino inclusive QE scattering from closed-shell nuclei. In the model the (nonrelativistic) hole states are taken to be states in a Woods-Saxon potential, while the final particles in the continuum are described with the DEB form of the RMF plus the so-called Darwin term.…”

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confidence: 99%

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Meson-exchange currents and final-state interactions in quasielastic electron scattering at high momentum transfers

et al. 2010

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The effects of meson-exchange currents (MEC) are computed for the one-particle one-hole transverse response function for finite nuclei at high momentum transfers q in the region of the quasi-elastic peak. A semirelativistic shell model is used for the one-particle-emission (e, e ) reaction. Relativistic effects are included using relativistic kinematics, performing a semirelativistic expansion of the current operators, and using the Dirac-equation-based (DEB) form of the relativistic mean-field potential for the final states. It is found that final-state interactions (FSI) produce an important enhancement of the MEC in the high-energy tail of the response function for q 1 GeV/c. The combined effect of MEC and FSI goes away when other models of the FSI, not based on the DEB potential, are employed. In recent years much of the emphasis in studies of inclusive (e, e ) scattering was placed on investigations of the scaling properties of the cross section and on the possibility of predicting neutrino cross sections assuming the universality of the scaling function for electromagnetic and weak interactions. An exhaustive analysis of (e, e ) world data demonstrated the scaling at energy transfers ω below the quasielastic (QE) peak [1,2], namely the independence of the reduced cross sections on the momentum transfer (first-kind scaling) and on the nuclear target (second-kind scaling) when plotted versus the appropriate scaling variable. It is well known that at energies above the QE peak scaling is violated in the transverse (T ) channel by effects beyond the impulse approximation: inelastic scattering [3,4], correlations, and meson-exchange currents (MEC) in both the one-particle one-hole (1p-1h) and two-particle two-hole (2p-2h) sectors [5][6][7][8].In contrast, the available data for the longitudinal (L) response are compatible with scaling throughout the QE region and permitted [9] the extraction of a phenomenological scaling function f L . In recent work [10][11][12] it was shown that only a few models [the relativistic mean field (RMF), the semirelativistic (SR) approach with Dirac-equation-based (DEB) and a "BCS-like" model] are capable of reproducing the detailed shape of f L , while other models fail to reproduce the long tail appearing at high ω. Theses models effectively account for the major ingredients needed to describe the (e, e ) responses for intermediate-to-high momentum transfers, namely relativistic effects and an appropriate description of the effective final-state interactions (FSI).Approximate treatments of these two ingredients are also possible using SR models, which have the advantage of permitting the use of standard nonrelativistic techniques when correctly extrapolated to high values of q. In this article we use the approach of Refs. [11,13] where a specific SR expansion of the electroweak single-nucleon current was used in a continuum shell-model description of electron and neutrino inclusive QE scattering from closed-shell nuclei. In the model the (nonrelativistic) hole states are taken to...

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Meson-exchange currents and final-state interactions in quasielastic electron scattering at high momentum transfers

et al. 2010

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“…The validity of the superscaling hypothesis, i.e., the existence of a universal scaling function in electroweak processes, constitutes an essential result which is supported by various theoretical studies [6][7][8]10] and gave rise to recent applications to neutrino studies [20,21]. The universal character of the scaling function is the basis of the SuperScaling Analysis (SuSA) introduced in [19].…”

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confidence: 98%

“…The use of traditional NR and SR approaches also leads to similar longitudinal and transverse scaling functions. This occurs for different descriptions of the FSI, namely, using the same Woods-Saxon potential as in the initial state, which leads to symmetrical scaling functions that do not agree with experiment [10], and making use of the DEB potential that produces the correct amount of asymmetry in the scaling function [8]. Finally, the RIA also leads to the fulfilment of zeroth-kind scaling when the plane wave limit is assumed [7], i.e., the final nucleon state is described as a free relativistic on-shell particle.…”

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“…This result also connects with the breaking of the zeroth-kind scaling (defined as the equality of the scaling functions obtained from the separated L and T contributions, viz., f L (ψ ) = f T (ψ ) = f (ψ )) observed in the data. From previous studies [7,8,10] it turned out that the zeroth-kind scaling is closely fulfilled by various models based on the impulse approximation. This is the case of the Relativistic Fermi Gas (RFG), by construction.…”

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Scaling and isospin effects in quasielastic lepton–nucleus scattering in the relativistic mean field approach

et al. 2007

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The role of isospin in quasielastic electron scattering and charge-changing neutrino reactions is investigated in the relativistic impulse approximation. We analyze proton and neutron scaling functions making use of various theoretical descriptions for the final-state interactions, focusing on the effects introduced by the presence of strong scalar and vector terms in the relativistic mean field approach. An explanation for the differences observed in the scaling functions evaluated from (e, e ) and (ν, μ) reactions is provided by invoking the differences in isoscalar and isovector contributions. © 2007 Elsevier B.V. All rights reserved. PACS: 25.30.Pt; 25.30.Fj; 24.10.Jv Extensive analyses of quasielastic (QE) inclusive electron scattering data performed in recent years [1][2][3][4] have clearly demonstrated the quality of the behavior known as scaling. These analyses are based on the so-called superscaling function, f (ψ ), obtained by dividing the cross section by an appropriate function which contains the single nucleon physics, and plotting the result against the scaling variable ψ (q, ω) (see, e.g., [5]). One then studies the dependences upon the momentum transfer q and the specific nucleus chosen. From (e, e ) world data one concludes that scaling of the first kind (no dependence on q) is reasonably respected at energies below the QE peak, whereas scaling of the second kind (no dependence on the nuclear species) is fulfilled very well in the same region. The simultaneous occurrence of both kinds of scaling is called superscaling. At energies above the QE peak, breaking of both * Corresponding author.E-mail address: jac@us.es (J.A. Caballero).kinds of scaling is observed, residing mostly in the transverse channel, and likely due to effects beyond the impulse approximation.Experimental data lead to a scaling function with a characteristic asymmetric shape, having a tail that extends to high values of the transferred energy ω (positive values of the scaling variable ψ (q, ω)). The asymmetric shape of the scaling function is largely absent in non-relativistic (NR) models based on a mean field approach. In contrast, the study presented in [6,7] has shown that the asymmetry can in fact be obtained within the relativistic impulse approximation (RIA), given that a description of final-state interactions (FSI) using strong relativistic mean field (RMF) potentials is assumed. Recently, we have shown [8] that an asymmetrical scaling function can be also obtained within the framework of a semi-relativistic (SR) model, based on improved NR expansions of the on-shell electromagnetic current, provided that the FSI are described by the Dirac equation-based (DEB) potential [9] derived from the RMF. Note that, in the SR model, the nonlocalities arising from the 0370-2693/$ -see front matter

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Neutrino-nucleus interactions

Donnelly

The IVth International Conference on Quarks and Nuclear Physics

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Semirelativistic description of quasielastic neutrino reactions and superscaling in a continuum shell model

Cited by 97 publications

References 68 publications

Meson-exchange currents and final-state interactions in quasielastic electron scattering at high momentum transfers

Meson-exchange currents and final-state interactions in quasielastic electron scattering at high momentum transfers

Scaling and isospin effects in quasielastic lepton–nucleus scattering in the relativistic mean field approach

Neutrino-nucleus interactions

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