Superscaling analyses of few-GeV inclusive electron scattering from nuclei are extended to include not only quasielastic processes, but also the region where excitation dominates. With reasonable assumptions about the basic nuclear scaling function extracted from data and information from other studies of the relative roles played by correlation and meson-exchange-current effects, it is shown that the residual strength in the resonance region can be accounted for through an extended scaling analysis. One observes scaling upon assuming that the elementary cross section by which one divides the residual to obtain a new scaling function is dominated by the N → transition and employing a new scaling variable suited to the resonance region. This yields a good representation of the electromagnetic response in both the quasielastic and regions. The scaling approach is then inverted and predictions are made for charge-changing neutrino reactions at energies of a few GeV, with focus placed on nuclei that are relevant to neutrino oscillation measurements. For this, a relativistic treatment of the required weak interaction vector and axial-vector currents for both quasielastic and -excitation processes is presented.

We present results for spectroscopic factors of the outermost shells in 40 Ca and 208 Pb, which have been derived from the comparison between the available quasielastic (e, e ′ p) data from NIKHEF-K and the corresponding calculated cross-sections obtained within a fully relativistic formalism. We include exactly the effect of Coulomb distortion on the electron wave functions and discuss its role in the extraction of the spectroscopic factors from experiment.Without any adjustable parameter, we find spectroscopic factors of about 70%, consistent with theoretical predictions. We compare our results with previous relativistic and nonrelativistic analyses of (e, e ′ p) data. In addition to Coulomb distortion effects we discuss different choices of the nucleon current operator and also analyze the effects due to the relativistic treatment of the outgoing-distorted and bound nucleon wave functions.

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.

Superscaling of the quasielastic cross section in charged-current neutrino-nucleus reactions at energies of a few GeV is investigated within the framework of the relativistic impulse approximation. Several approaches are used to describe final-state interactions and comparisons are made with the plane-wave approximation. Superscaling is very successful in all cases. The scaling function obtained using a relativistic mean field for the final states shows an asymmetric shape with a long tail extending towards positive values of the scaling variable, in excellent agreement with the behavior presented by the experimental scaling function. DOI: 10.1103/PhysRevLett.95.252502 PACS numbers: 25.30.Pt, 13.15.+g, 24.10.Jv In the context of inclusive quasielastic (QE) electron scattering at intermediate to high energies, the concepts of scaling [1] and superscaling [2] have been explored in previous work [3,4], where an exhaustive analysis of the e; e 0 world data demonstrated the quality of the scaling behavior. Scaling of the first kind (no dependence on the momentum transfer) is reasonably well respected at excitation energies below the QE peak, whereas scaling of the second kind (no dependence on the nuclear species) is excellent in the same region. The simultaneous occurrence of both kinds of scaling is called superscaling. At energies above the QE peak both scaling of the first and, to a lesser extent, of the second kind are shown to be violated because of important contributions introduced by effects beyond the impulse approximation, namely, inelastic scattering [5] together with correlations and meson exchange currents in both the 1p-1h and 2p-2h sectors [6,7].The scaling analysis of e; e 0 data has recently been extended through the QE peak into the region [8]. Of relevance to the present work we note that the high-energy inclusive electron scattering cross section is well represented up to the peak using the scaling ideas, importantly, with an asymmetric QE scaling function. In that study the scaling approach was also used to predict nuclear ; cross sections, based on the assumption of a universal scaling function, valid for both electron and neutrino scattering at corresponding kinematics.In this Letter we investigate the QE scaling properties of charged-current (CC) neutrino-nucleus scattering within the context of the relativistic impulse approximation (RIA). After verifying that various RIA models do superscale, we compare the associated scaling functions with the e; e 0 phenomenological one referred to above. This allows a check on the consistency of the universality assumption and on the capabilities of different models to yield the required properties of the experimental scaling function, specifically, its asymmetric form.Here we follow the general procedure of scaling and superscaling studies, namely, we first construct inclusive cross sections within a model and then obtain scaling functions by dividing them by the relevant single-nucleon cross sections weighted by the corresponding proton and neutron...

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.

The so-called semirelativistic expansion of the weakly charged current in powers of the initial nucleon momentum is performed to describe charge-changing, quasielastic neutrino reactions (ν µ , µ − ) at intermediate energies. The quality of the expansion is tested by comparing it with the relativistic Fermi gas model using several choices of kinematics of interest for ongoing neutrino oscillation experiments. The new current is then implemented in a continuum shell model together with relativistic kinematics to investigate the scaling properties of (e, e ) and (ν µ , µ − ) cross sections.

The issue of factorization within the context of coincidence quasi-elastic electron scattering is reviewed. Using a relativistic formalism for the entire reaction mechanism and restricting ourselves to the case of plane waves for the outgoing proton, we discuss the meaning of factorization in the cross section and the role of the small components of the bound nucleon wave function. PACS number(s): 25.30.Fj, 24.10.Jv, 21.10.Jx

Predictions for electron induced proton knockout from p 1͞2 and p 3͞2 shells in 16 O are presented using various approximations for the relativistic nucleonic current. Results for differential cross section, transverse-longitudinal response (R TL ), and left-right asymmetry A TL are compared at jQ 2 j 0.8͑GeV͞c͒ 2 . We show that there are important dynamical and kinematical relativistic effects which can be tested by experiment. PACS numbers: 25.30.Fj, 21.60.Cs, 25.30.Rw The exclusive ͑e, e 0 p͒ coincidence measurement allows the determination of the missing energy (E m ) and missing momentum ( p m , the momentum of the recoiling nucleus) in the reaction, and information on the energies, momentum distributions, and spectroscopic factors of bound nucleons is provided [1,2]. Until recently low-E m data were concentrated at p m # 300 MeV͞c. Now higher p m regions are being probed at small E m under quasielastic conditions [3], yielding new information of high momentum components of bound nucleons in a regime (Bjorken x Ӎ 1) where two-body currents can be safely neglected [4,5]. Most theoretical work on ͑e, e 0 p͒ has been based on nonrelativistic approximations to the nucleon current, namely the standard distorted-wave impulse approximation (DWIA) [1]. DWIA data analyses [2] have met two major difficulties: (a) The spectroscopic factors extracted from low-p m (p m , 300 MeV͞c) data are too small (for instance, S a Ӎ 0.5 for 3s 1͞2 and 2d 5͞2 orbits in 208 Pb [2,6]), while theories on short-range correlations [7] predict at most a 30% reduction of mean-field occupations (S a . 0.7) for levels just below the Fermi level. (b) DWIA calculations compatible with the low-p m data predict much smaller cross sections at high p m (p m . 300 MeV͞c) than those experimentally observed [6]. Short-range correlations are expected to increase the high-momentum components, but their effect is negligible [8] at the small missing energies of these high-p m data [6], and long-range correlations have been introduced to explain the high-p m data within the nonrelativistic formalism [4,6].In recent years the relativistic mean-field approximation has been sucessfully used for the analyses of both low-p m [9-13] and high-p m [14] data. In the relativistic distorted-wave impulse approximation (RDWIA), the nucleon currentis calculated with relativistic c B (c F ) wave function for the initial bound (final outgoing) nucleon.Ĵ m N is the relativistic nucleon current operator of cc1 or cc2 forms as in [15]. For c B we use Dirac-Hartree solutions from relativistic Lagrangians with scalar and vector meson terms [16]. For c F we compute a solution of the Dirac equation with scalar-vector (S-V) global optical potentials [17]. The only fitted parameter is the spectroscopic factor [10-13]. These RDWIA spectroscopic factors are larger than the DWIA ones [11][12][13], and are valid both for low-and high-p m data [14].Exploratory studies within the relativistic plane wave impulse approximation (RPWIA), where the interaction in the final state (FSI) be...