Determination of the nucleon axial vector form-factor from πΔ electroproduction near threshold

This paper is a continuation of previous work about the effects of a phenomenological flavour dependent force in a relativistically covariant constituent quark model based on the Salpeter equation on the structure of light-flavoured baryon resonances. Here the longitudinal and transverse helicity amplitudes as studied experimentally in the electro-excitation of nucleon-and ∆ resonances are calculated. In particular the amplitudes for the excitation of three and four star resonances as calculated in a previous model A are compared to those of the novel model C as well as to existing and partially new experimental data such as e.g. determined by the CB-ELSA collaboration. A brief discussion of some improvements to model C is given after the introduction.

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“…Amaldi [47] Brauel [48] Bloom [49] D. Guerra [50] Joos [51] Baker [52] Miller [53] Kita. [54,55] Allasia [56] model C [1] impr.…”

Section: Improvements To Model Cmentioning

confidence: 99%

Effects of a spin-flavour-dependent interaction on light-flavoured baryon helicity amplitudes

Michael

Metsch

2013

Eur. Phys. J. A

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“…We fit the pion electroproduction data as reported in [25], from various sources [95][96][97][98][99], and the neutrino-scattering data as reported in [20], from various sources [12,13,17,18,100]. The pion electroproduction data can be interpreted in different theory frameworks to extract the form factor.…”

Section: B Fit Of the Electromagnetic Form Factor To Electron Scattementioning

confidence: 99%

“…We consider here separately several cases: the Soft Pion approximation [95], the Partially Conserved Axial Current approximation (PCAC) [96], the Furlan approximation (enhanced soft pion production) [97] and the Dombey and Read approximation [98]. Data corresponding to ∆ excitation [99] are considered separately. The spread between the different approximations and sets of data is sizable and should be considered as an intrinsic systematic uncertainty in the extraction of the form factor.…”

Section: B Fit Of the Electromagnetic Form Factor To Electron Scattementioning

confidence: 99%

New evaluation of the axial nucleon form factor from electron- and neutrino-scattering data and impact on neutrino-nucleus cross sections

et al. 2020

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A joint fit to neutrino-nucleon scattering and pion electroproduction data is performed to evaluate the nucleon axial form factor in the two-component model consisting of a three-quark intrinsic structure surrounded by a meson cloud. Further constrains on the model are obtained by reevaluating the electromagnetic form factor using electron scattering data. The results of the axial form factor show sizable differences with respect to the widely used dipole model. The impact of such changes on the Charged-Current Quasi-Elastic neutrino-nucleus cross-section is evaluated in the SuSAv2 nuclear model, based on the Relativistic Mean Field and including the contribution of two-body currents. How the different parametrizations of the axial form factor affect the crosssection prediction is assessed in full details and comparisons to recent T2K and MINERvA data are presented.

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“…using the Fermi-Gas approximation and some relevant nuclear and reaction effects thereof. Experimental data are from refs [42][43][44][45][46]. (exp1) and[47][48][49][50] (exp2).…”

mentioning

confidence: 99%

Axial-vector dominance predictions in quasielastic neutrino-nucleus scattering

Amaro

Arriola

2016

Phys. Rev. D

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The axial form factor plays a crucial role in quasielastic neutrino-nucleus scattering, but the error of the theoretical cross section due to uncertainties of GA remains to be established. Reversely, the extraction of GA from the neutrino nucleus cross section suffers from large systematic errors due to nuclear model dependencies, while the use of single parameter dipole fits underestimates the errors and prevents an identification of the relevant kinematics for this determination. We propose to use a generalized axial-vector-meson-dominance (AVMD) in conjunction with large-Nc and high energy QCD constrains to model the nucleon axial form factor, as well as the half width rule as an a priori uncertainty estimate. The minimal hadronic ansatz comprises the sum of two monopoles corresponding to the lightest axial-vector mesons being coupled to the axial current. The parameters of the resulting axial form factor are the masses and widths of the two axial mesons as obtained from the averaged PDG values. By applying the half width rule in a Monte Carlo simulation, a distribution of theoretical predictions can then be generated for the neutrino-nucleus quasielastic cross section. We test the model by applying it to the (νµ, µ) quasielastic cross section from 12 C for the kinematics of the MiniBooNE experiment. The resulting predictions have no free parameters. We find that the relativistic Fermi gas model globally reproduces the experimental data, giving χ 2 /#bins = 0.81. A Q 2 -dependent error analysis of the neutrino data shows that the uncertainties in the axial form factor GA(Q 2 ) are comparable to the ones induced by the a priori half width rule. We identify the most sensitive region to be in the range 0.2 Q 2 0.6 GeV 2 .

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Determination of the nucleon axial vector form-factor from πΔ electroproduction near threshold

Cited by 37 publications

References 16 publications

Effects of a spin-flavour-dependent interaction on light-flavoured baryon helicity amplitudes

Effects of a spin-flavour-dependent interaction on light-flavoured baryon helicity amplitudes

New evaluation of the axial nucleon form factor from electron- and neutrino-scattering data and impact on neutrino-nucleus cross sections

Axial-vector dominance predictions in quasielastic neutrino-nucleus scattering

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