We discuss the observed disagreement between the Q^2 distributions of neutrino-nucleus quasielastic events, measured by a number of recent experiments, and the predictions of Monte Carlo simulations based on the relativistic Fermi gas model. The results of our analysis suggest that these discrepancies are likely to be ascribable to both the breakdown of the impulse approximation and the limitations of the Fermi gas description. Several issues related to the extraction of the Q^2 distributions from the experimental data are also discussed, and new kinematical variables, which would allow for an improved analysis, are proposed.
The work concerns the quasielastic charged current neutrino-neutron and antineutrino-proton interactions. Single, double, and triple spin asymmetries are computed and analyzed. The spin asymmetries are sensitive to the axial form factor of the nucleon. In particular, the target-recoil double spin asymmetry and the lepton-target-recoil triple spin asymmetry depend strongly on the axial form factor of the nucleon. Indeed, the sign and shape of these components depend on the axial mass parameter. All the asymmetries, except the lepton polarization, are observables well suited to study the nonstan…
We show that the quasielastic (QE) response calculated with the SuSAv2 (superscaling approach) model, that relies on the scaling phenomenon observed in the analysis of (e,e') data and on the relativistic mean-field theory, is very similar to that from a relativistic distorted wave impulse approximation model when only the real part of the optical potentials is employed. The coincidence between the results from these two completely independent approaches, which satisfactorily agree with the inclusive data, reinforces the reliability of the quasielastic predictions stemming from both models and …
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 $G_A$ remains to be established. Reversely, the extraction of $G_A$ 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-$N_c$ and hig…
We use a recent scaling analysis of the quasielastic electron scattering data from $^{12}$C to predict the quasielastic charge-changing neutrino scattering cross sections within an uncertainty band. We use a scaling function extracted from a selection of the $(e,e')$ cross section data, and an effective nucleon mass inspired by the relativistic mean-field model of nuclear matter. The corresponding super-scaling analysis with relativistic effective mass (SuSAM*) describes a large amount of the electron data lying inside a phenomenological quasielastic band. The effective mass incorporates the e…
We develop an asymmetric relativistic Fermi gas model for the study of the electroweak nuclear response in the quasielastic region. The model takes into account the differences between neutron and proton densities in asymmetric (N > Z) nuclei, as well as differences in the neutron and proton separation energies. We present numerical results for both neutral and charged current processes, focusing on nuclei of interest for ongoing and future neutrino oscillation experiments. We point out some important differences with respect to the commonly employed symmetric Fermi gas model.
We present a discussion of models of nuclear effects used to describe an inclusive electron-nucleus scattering in the quasielastic (QE) peak region, aiming to compare them and draw conclusion of their reliability when applied in neutrino-nucleus interactions. A basic motivation is to reduce systematic errors in neutrino oscillation experiments. We concentrate on the neutrino energy profile of the T2K experiment, which provides us a region of the greatest importance in terms of the highest contribution to the charge-current quasielastic (CCQE) cross section. We choose only electron-nucleus data…
The expressions for the overall effect of Pauli blocking in quasielastic (QE) lepton scattering from nuclear targets within the framework of the Relativistic Fermi Gas (RFG) given in several publications are incorrect. For example, the expressions published by Bell and Llewelyn Smith in 1972 are incorrect (probably a typographical error). The expressions for Pauli blocking presented in several subsequent publications including the paper of C.H. Llewelyn Smith in 1972 and the paper of Paschos and Yu in 2002 have the same error. Another example is a 1992 paper by Singh and Oset which has a diffe…
We review some recent progress in the study of electroweak interactions in nuclei within the SuSAv2-MEC model. The model has the capability to predict (anti)neutrino scattering observables on different nuclei. The theoretical predictions are compared with the recent T2K $ν_μ-^{16}$O data and good agreement is found at all kinematics. The results are very similar to those obtained for $ν_μ-^{12}$C scattering, except at low energies, where some differences emerge. The role of meson-exchange currents in the two-particle two-hole channel is analyzed in some detail. In particular it is shown that t…
Polarization transfer observables for quasielastic proton-nucleus scattering in terms of a complete Lorentz invariant representation of the NN scattering matrix
Martini et al. [Phys. Rev. C 94, 015501 (2016)] recently observed that when the produced-lepton's mass plays an important role, the charged-current quasielastic cross section for muon neutrinos can be higher than that for electron neutrinos. Here I argue that this effect appears solely in the theoretical descriptions of nuclear effects in which nucleon knockout requires the energy and momentum transfers to lie in a narrow range of the kinematically allowed values.
