G. D. Megias

Charged-current neutrino-nucleus reactions within the superscaling meson-exchange current approach

We present a detailed study of charged-current (CC) neutrino-nucleus reactions in a fully relativistic framework and comparisons with recent experiments spanning an energy range from hundreds of MeV up to 100 GeV within the SuperScaling Approach, which is based on the analysis of electronnucleus scattering data and has been recently improved with the inclusion of Relativistic Mean Field theory effects. We also evaluate and discuss the impact of two-particle two-hole meson-exchange currents (2p-2h MEC) on neutrino-nucleus interactions through the analysis of two-particle two-hole axial and vector contributions to weak response functions in a fully relativistic Fermi gas. The results show a fairly good agreement with experimental data over the whole range of neutrino energies.

Extensions of superscaling from relativistic mean field theory: The SuSAv2 model

We present a systematic analysis of the quasielastic scaling functions computed within the relativistic mean field (RMF) theory and we propose an extension of the superscaling approach (SuSA) model based on these results. The main aim of this work is to develop a realistic and accurate phenomenological model (SuSAv2), which incorporates the different RMF effects in the longitudinal and transverse nuclear responses, as well as in the isovector and isoscalar channels. This provides a complete set of reference scaling functions to describe in a consistent way both (e,e � ) processes and the neutrino/antineutrino-nucleus reactions in the quasielastic region. A comparison of the model predictions with electron and neutrino scattering data is presented.

Meson-exchange currents and quasielastic predictions for charged-current neutrino-C 12 scattering in the superscaling approach

We evaluate and discuss the impact of meson-exchange currents (MECs) on charged-current quasielastic neutrino cross sections. We consider the nuclear transverse response arising from two-particle two-hole states excited by the action of electromagnetic, purely isovector meson-exchange currents in a fully relativistic framework based on the work by the Torino Collaboration [A. D. Pace, M. Nardi, W. M. Alberico, T. W. Donnelly, and A. Molinari, Nucl. Phys. A726, 303 (2003)]. An accurate parametrization of this MEC response as a function of the momentum and energy transfers involved is presented. Results of neutrino-nucleus cross sections using this MEC parametrization together with a recent scaling approach for the one-particle one-hole contributions (named SuSAv2) are compared with experimental data.

Charged-current inclusive neutrino cross sections in the SuperScaling model including quasielastic, pion production and meson-exchange contributions

Charged current inclusive neutrino-nucleus cross sections are evaluated using the superscaling model for quasielastic scattering and its extension to the pion production region. The contribution of two-particle-two-hole vector meson-exchange current excitations is also considered within a fully relativistic model tested against electron scattering data. The results are compared with the inclusive neutrino-nucleus data from the T2K and SciBooNE experiments. For experiments where

Nuclear effects in neutrino and antineutrino charged-current quasielastic scattering at MINERνA kinematics

\langle E_\nu \rangle \sim 0.8

The frozen nucleon approximation in two-particle two-hole response functions

GeV, the three mechanisms considered in this work provide good agreement with the data. However, when the neutrino energy is larger, effects from beyond the

Emission of neutron–proton and proton–proton pairs in neutrino scattering

\Delta

Two-nucleon emission in neutrino and electron scattering from nuclei: The modified convolution approximation

also appear to be playing a role. The results show that processes induced by two-body currents play a minor role at the kinematics considered.

Estimate of the theoretical uncertainty of the cross sections for nucleon knockout in neutral-current neutrino-oxygen interactions

We compare the charged-current quasielastic neutrino and antineutrino observables obtained in two different nuclear models, the phenomenological SuperScaling Approximation and the relativistic mean field approach, with the recent data published by the MINER nu A Collaboration. Both models provide a good description of the data without the need of an ad hoc increase in the mass parameter in the axial-vector dipole form factor. Comparisons are also made with the MiniBooNE results, where different conclusions are reached.

Meson-exchange currents and quasielastic predictions for neutrino-nucleus scattering

Abstract We present a fast and efficient method to compute the inclusive two-particle two-hole (2p–2h) electroweak responses in the neutrino and electron quasielastic inclusive cross sections. The method is based on two approximations. The first neglects the motion of the two initial nucleons below the Fermi momentum, which are considered to be at rest. This approximation, which is reasonable for high values of the momentum transfer, turns out also to be quite good for moderate values of the momentum transfer q ≳ k F . The second approximation involves using in the “frozen” meson-exchange currents (MEC) an effective Δ-propagator averaged over the Fermi sea. Within the resulting “frozen nucleon approximation”, the inclusive 2p–2h responses are accurately calculated with only a one-dimensional integral over the emission angle of one of the final nucleons, thus drastically simplifying the calculation and reducing the computational time. The latter makes this method especially well-suited for implementation in Monte Carlo neutrino event generators.