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We study the phase-space dependence of 2p-2h excitations in neutrino scattering using the relativistic Fermi gas model. We follow a similar approach to other authors, but focusing in the phase-space properties, comparing with the non-relativistic model. A careful mathematical analysis of the angular distribution function for the outgoing nucleons is performed. Our goals are to optimize the CPU time of the 7D integral to compute the hadron tensor in neutrino scattering, and to conciliate the different relativistic and non relativistic models by describing general properties independently of the two-body current. For some emission angles the angular distribution becomes infinite in the Lab system, and we derive a method to integrate analytically around the divergence. Our results show that the frozen approximation, obtained by neglecting the momenta of the two initial nucleons inside the integral of the hadron tensor, reproduces fairly the exact response functions for constant current matrix elements., Comment: 8 pages, 4 figures. Contribution to 16th International Workshop on Neutrino Factories and Future Neutrino Beam Facilities, 25-30 August, 2014. Held at University of Glasgow, United Kingdom

We construct a coordinate-space chiral potential, including $\Delta$-isobar intermediate states in its two-pion-exchange component. The contact interactions entering at next-to-leading and next-to-next-to-next-to-leading orders ($Q^2$ and $Q^4$, respectively, $Q$ denoting generically the low momentum scale) are rearranged by Fierz transformations to yield terms at most quadratic in the relative momentum operator of the two nucleons. The low-energy constants multiplying these contact interactions are fitted to the 2013 Granada database, consisting of 2309 $pp$ and 2982 $np$ data (including, respectively, 148 and 218 normalizations) in the laboratory-energy range 0--300 MeV. For the total 5291 $pp$ and $np$ data in this range, we obtain a $\chi^2$/datum of roughly 1.3 for a set of three models characterized by long- and short-range cutoffs, $R_{\rm L}$ and $R_{\rm S}$ respectively, ranging from $(R_{\rm L},R_{\rm S})=(1.2,0.8)$ fm down to $(0.8,0.6)$ fm. The long-range (short-range) cutoff regularizes the one- and two-pion exchange (contact) part of the potential., Comment: 32 pages, 19 figures, accepted for publication as a Regular Article in Physical Review C

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 (MiniBooNE, MINERvA, NOMAD and T2K Collaborations)., Comment: 16 pages, 19 figures

Recent progresses on the relativistic modeling of neutrino-nucleus reactions are presented and the results are compared with high precision experimental data in a wide energy range., Comment: 10 pages, 5 figures, Proccedings of the 33rd International Workshop on Nuclear Theory, IWNT33-14, Rila Mountains, Bulgaria, June 22-28, 2014

We present a new phenomenological Nucleon-Nucleon chiral potential fitted to 925 pp and 1743 np scattering data selected from the Granada-2013 NN-database up to a laboratory energy of $125$ MeV with 20 short distance parameters and three chiral constants $c_1$, $c_3$ and $c_4$ with $\chi^2/\nu = 1.02$. Special attention is given to testing the normality of the residuals which allows for a sound propagation of statistical errors from the experimental data to the potential parameters, phase-shifts, scattering amplitudes and counter-terms. This fit allows for a new determination of the chiral constants $c_1$, $c_3$ and $c_4$ compatible with previous determinations from NN data. This new interactions is found to be softer than other high quality potentials by undertaking a Weinberg eigenvalue analysis. We further explore the interplay between the error analysis and the assumed form of the short distance interaction. The present work shows that it is possible to fit NN scattering with a TPE chiral potential fulfilling all necessary statistical requirements up to 125 MeV and shows unequivocal non-vanishing D-wave short distance pieces., Comment: 16 pages, 10 figures, 5 tables. Enlarged version including Weinberg eigenvalue analysis and cut-off dependence

We analyze the low energy NN interaction by confronting statistical vs systematic uncertainties. This is carried out with the help of model potentials fitted to the Granada-2013 database where a statistically meaningful partial wave analysis comprising a total of $6713$ np and pp published scattering data from 1950 till 2013 below $350 {\rm MeV}$ has been made. We extract threshold parameters uncertainties from the coupled channel effective range expansion up to $j \le 5$. We find that for threshold parameters systematic uncertainties are generally at least an order of magnitude larger than statistical uncertainties. Similar results are found for np phase-shifts and amplitude parameters., Comment: 18 pages. 6 tables. 8 Figures. Includes results presented at Workshop on Information and Statistics in Nuclear Experiment and Theory (ISNET-3) ECT* Trento, Italy, 16-20 November 2015. To appear in Jour. Phys. G

We study the dynamics of two kinds of entanglement, and there interplay. On one hand, the intrinsic entanglement within a central system composed by three two level atoms, and measured by multipartite concurrence, on the other, the entanglement between the central system and a cavity, acting as an environment, and measured with purity. Using dipole-dipole and Ising interactions between atoms we propose two Hamiltonians, a homogeneous and a quasi-homogeneous one. We find an upper bound for concurrence as a function of purity, associated to the evolution of the $W$ state. A lower bound is also observed for the homogeneous case. In both situations, we show the existence of critical values of the interaction, for which the dynamics of entanglement seem complex., Comment: 10 pages, closest to journal version

We compute the binding energy of triton with realistic statistical errors stemming from NN scattering data uncertainties and the deuteron and obtain $E_t=-7.638(15) \, {\rm MeV}$. Setting the numerical precision as $\Delta E_t^{\rm num} \lesssim 1 \, {\rm keV}$ we obtain the statistical error $\Delta E_t^{\rm stat}= 15(1) \, {\rm keV}$ which is mainly determined by the channels involving relative S-waves. This figure reflects the uncertainty of the input NN data, more than two orders of magnitude larger than the experimental precision $\Delta E_t^{\rm exp}= 0.1 \, {\rm keV}$ and provides a bottleneck in the realistic precision that can be reached. This suggests an important reduction in the numerical precision and hence in the computational effort., Comment: 4 pages, 1 figure, 1 table

The angular distribution of the phase space arising in two-particle emission reactions induced by electrons and neutrinos is computed in the laboratory (Lab) system by boosting the isotropic distribution in the center of mass (CM) system used in Monte Carlo generators. The Lab distribution has a singularity for some angular values, coming from the Jacobian of the angular transformation between CM and Lab systems. We recover the formula we obtained in a previous calculation for the Lab angular distribution. This is in accordance with the Monte Carlo method used to generate two-particle events for neutrino scattering\cite{Sob12}. Inversely, by performing the transformation to the CM system, it can be shown that the phase-space function, which is proportional to the two particle-two hole (2p-2h) hadronic tensor for a constant current operator, can be computed analytically in the frozen nucleon approximation, if Pauli blocking is absent. The results in the CM frame confirm our previous work done using an alternative approach in the Lab frame. The possibilities of using this method to compute the hadronic tensor by a boost to the CM system are analyzed., Comment: 7 pages, 3 figures. Minor revision. Updated references

We use the Monte Carlo bootstrap as a method to simulate pp and np scattering data below pion production threshold from an initial set of over 6700 experimental mutually $3\sigma$ consistent data. We compare the results of the bootstrap, with 1020 statistically generated samples of the full database, with the standard covariance matrix method of error propagation. No significant differences in scattering observables and phase shifts are found. This suggests alternative strategies for propagating errors of nuclear forces in nuclear structure calculations., Comment: 5 pages, 3 figures

The Nucleon-Nucleon interaction is the starting point for ab initio Nuclear Structure and Nuclear reactions calculations. Those are effectively carried out via effective interactions fitting scattering data up to a maximal center of mass momentum. However, NN interactions are subjected to statistical and systematic uncertainties which are expected to propagate and have some impact on the predictive power and accuracy of theoretical calculations, regardless on the numerical accuracy of the method used to solve the many body problem. We stress the necessary conditions required for a correct and self-consistent statistical interpretation of the discrepancies between theory and experiment which enable a subsequent statistical error propagation and correlation analysis. We comprehensively discuss an stringent and recently proposed tail-sensitive normality test and provide a simple recipe to implement it. As an application, we analyze the deduced uncertainties and correlations of effective interactions in terms of Moshinsky-Skyrme parameters and effective field theory counterterms as derived from the bare NN potential containing One-Pion-Exchange and Chiral Two-Pion-Exchange interactions inferred from scattering data., Comment: 17 pages, 4 figures, 4 tables. Remarks added and typos corrected. Submitted to JPhysG Focus issue "Enhancing the interaction between nuclear experiment and theory through information and statistics" (ISNET)

Two-particle two-hole contributions to electroweak response functions are computed in a fully relativistic Fermi gas, assuming that the electroweak current matrix elements are independent of the kinematics. We analyze the genuine kinematical and relativistic effects before including a realistic meson-exchange current (MEC) operator. This allows one to study the mathematical properties of the non-trivial seven-dimensional integrals appearing in the calculation and to design an optimal numerical procedure to reduce the computation time. This is required for practical applications to CC neutrino scattering experiments, where an additional integral over the neutrino flux is performed. Finally we examine the viability of this model to compute the electroweak 2p-2h response functions., Comment: Major revision (shortened). 22 pages, 18 figures

Nucleon-Nucleon potentials are commonplace in nuclear physics and are determined from a finite number of experimental data with limited precision sampling the scattering process. We study the statistical assumptions implicit in the standard least squares fitting procedure and apply, along with more conventional tests, a tail sensitive quantile-quantile test as a simple and confident tool to verify the normality of residuals. We show that the fulfilment of normality tests is linked to a judicious and consistent selection of a nucleon-nucleon database. These considerations prove crucial to a proper statistical error analysis and uncertainty propagation. We illustrate these issues by analyzing about 8000 proton-proton and neutron-proton scattering published data. This enables the construction of potentials meeting all statistical requirements necessary for statistical uncertainty estimates in nuclear structure calculations., Comment: 20 pages. 13 figures. 10 tables, (minor numerical changes) Physical Review C (to appear)

We analyze chiral interactions to N2LO on the light of proton-proton and neutron-proton scattering data published from 1950 till 2013 and discuss conditions under which the chiral coefficients can be extracted, Comment: 4 pages, 2 figures, 3 tables. Presented at the 22th European Conference On Few-Body Problems In Physics: EFB22 9 - 13 Sep 2013, Krakow (Poland)

We estimate the expected errors of nuclear matrix elements coming from the uncertainty on the NN interaction. We use a coarse grained (GR) interaction fitted to NN scattering data, with several prescriptions for the long-part of the interaction, including one pion exchange and chiral two-pion exchange interactions., Comment: Presented at the 22th European Conference On Few-Body Problems In Physics: EFB22 9 - 13 Sep 2013, Krakow (Poland)

We determine the chiral constants of the Nucleon-Nucleon Two Pion Exchange potential deduced from Chiral Perturbation Theory. By using a coarse grained representation of the short distance interactions with 30 parameters, the Partial Wave Analysis fit gives chi^2/dof = 1.1 to a mutually consistent set of 6713 data previously built from all published proton-proton and neutron proton scattering data from 1950 till 2013 with LAB energy below 350 MeV. We obtain (c1, c3, c4)=(-0.41+- 1.08,-4.66+- 0.60, 4.31+- 0.17)/GeV with an almost 100% anti-correlation between c1 and c3. We also provide the errors in the short distance parameters and propagate them to the deuteron properties and low partial waves phase shifts., Comment: 11 pages, 7 figures, 11 tables. Enlarged version

Using the delta-shell representation we present a successful fit to neutron-proton and proton-proton scattering data below pion production threshold. A detailed overview of the theory necessary to calculate observables with this potential is presented. A new data selection process is used to obtain the largest mutually consistent data base. The analysis includes data within the years 1950 to 2013. Using 46 parameters we obtain chi^2/Ndata = 1.04 with Ndata = 6713 including normalization data. Phase shifts with error bars are provided., Comment: 32 pages, 1 figure, 10 tables

Data on $\Lambda\Lambda$ hypernuclei provide a unique method to learn details about the strangeness S =- 2 sector of the baryon-baryon interaction. From the free space Bonn-J\"ulich potentials, determined from data on baryon-baryon scattering in the S = 0, -1 channels, we construct an interaction in the S =-2 sector to describe the experimentally known LL hypernuclei. After including short-range (Jastrow) and RPA correlations, we find masses for these LL hypernuclei in a reasonable agreement with data, taking into account theoretical and experimental uncertainties. Thus, we provide a natural extension, at low energies, of the Bonn-J\"ulich one-boson exchange potentials to the S =-2 channel., Comment: Contribution for the Conference Proceedings of the Compact Stars in the QCD Phase Diagram III (CSQCD III), December 12-15, 2012, Guaruj\'a, Brazil. http://www.astro.iag.usp.br/~foton/CSQCD3

We compare the predictions of the SuperScaling model for charged current quasielastic muonic neutrino and antineutrino scattering from $^{12}$C with experimental data spanning an energy range up to 100 GeV. We discuss the sensitivity of the results to different parametrizations of the nucleon vector and axial-vector form factors. Finally, we show the differences between electron and muon (anti-)neutrino cross sections relevant for the $\nu$STORM facility., Comment: 14 pages, 7 figures; v2: small corrections in the text and two added references; version accepted for publication by Phys. Lett. B

We undertake a simultaneous partial wave analysis to proton-proton and neutron-proton scattering data below pion production threshold up to LAB energies of 350MeV. We represent the interaction as a sum of delta-shells in configuration space below 3fm and a charge dependent one pion exchange potential above 3fm together with electromagnetic effects. We obtain chi^2 = 2813|pp + 3985|np with a total of N = 2747|pp + 3691|np data obtained till 2013 and a total number of 46 fitting parameters yielding chi^2 /d.o.f = 1.06. Special attention is paid to estimate the errors of the phenomenological interaction as well as the derived effects on the phase-shifts and scattering amplitudes., Comment: 8 pages, 6 figures, 2 tables. Enlarged discussion on fits and database

The superscaling approach (SuSA) to neutrino-nucleus scattering, based on the assumed universality of the scaling function for electromagnetic and weak interactions, is reviewed. The predictions of the SuSA model for bot CC and NC differential and total cross sections are presented and compared with the MiniBooNE data. The role of scaling violations, in particular the contribution of meson exchange currents in the two-particle two-hole sector, is explored., Comment: 5 pages, 6 figures, Proceedings of NUINT 2012, Rio de Janeiro, October 2012

We analyse the interplay between nucleon-nucleon potentials deduced from chiral perturbation theory and a coarse grained representation of the short distance interactions by delta-shells potentials below a certain cut-off distance. While we find that the number of parameters is greatly reduced when Chiral Two Pion Exchange contributions are included we also observe that discerning the necessity of improvements on the interaction requires a detailed analysis of all error sources. Our points are best illustrated by computing deuteron static properties as well as electromagnetic form factors after error propagation., Comment: 6 pages, 3 figures, Presented by R. Navarro Perez at the The 7th International Workshop on Chiral Dynamics, August 6 -10, 2012, Jefferson Lab, Newport News, Virginia, USA

We determine two-body Skyrme force parameters from a Nucleon-Nucleon interaction as a function of the maximal momentum fitting NN scattering data. We find general agreement with Vlowk interactions based on high quality potentials., Comment: 4 page, 1 figure, Presented by R.N.P. at the 20th International IUPAP Conference on Few-Body Problems in Physics, 20 - 25 August, 2012, Fukuoka, Japan

There is an increasing interest in quantifying the predictive power in nuclear structure calculations. We discuss how both experimental and systematic errors at the NN-level can be used to estimate the theoretical uncertainties by rather simple means and without solving the full nuclear many body problem. We emphasize the role of effective interactions defined by coarse graining the NN potential to length scales of the order of the minimal de Broglie wavelength probed between nucleons in nuclei. We find an a priori error of \DeltaB/A \sim 0.1 - 0.4MeV for the binding energy per particle throughout the periodic table for 2 \leq A \leq 208, and a linear growth of the error with density for nuclear matter \DeltaB/A \sim 3.75{\rho}n.m. and neutron matter \DeltaB/N \sim 3.5{\rho}n.. This suggests to limit the computational effort in solving the Nuclear Many Body Problem to such an accuracy., Comment: 6 pages. 2 figures. Presented by RNP at Sixth International Conference on Quarks and Nuclear Physics, April 16-20, 2012. Ecole Polytechnique, Palaiseau, Paris, France

Despite great theoretical efforts the NN interaction can only be determined with a finite precision, implying an error upper bound for nuclear masses. We analyze for the first time the problem of estimating the systematic errors related to the form of the potential and their impact on nuclear binding. To this end we exploit the concept of coarse grained interactions to typical nuclear wavelengths. Our estimate gives an error of 0.1-0.4 MeV for the binding energy per particle and paves the way for ab initio calculations tailored to such a precision., Comment: 4 pages, 2 figures, 1 table

We provide a successful fit for proton-neutron scattering below pion production threshold up to LAB energies of 350 MeV. We use seven high-quality fits based on potentials with different forms as a measure of the systematic uncertainty. We represent the interaction as a sum of delta-shells in configuration space below the 3fm and a charge dependent one pion exchange potential above 3fm together with magnetic and vacuum polarization effects. Special attention is paid to estimate the errors of the phenomenological interaction., Comment: 5 pages, 2 figures. Comments and one figure with differential observables added

We evaluate quasielastic double-differential antineutrino cross sections obtained in a phenomenological model based on the superscaling behavior of electron scattering data and estimate the contribution of the vector meson-exchange currents in the 2p-2h sector. We show that the impact of meson-exchange currents for charge-changing antineutrino reactions is much larger than in the neutrino case., Comment: 4 pages, 4 figures

We consider a coarse graining of NN interactions in coordinate space very much in the spirit of the well known Vlowk approach. To this end we sample the interaction at about the minimal de Broglie wavelength probed by NN scattering below pion production threshold. This amounts to provide a simple delta-shell potential plus the standard OPE potential above 2 fm. The possible simplifications in the Nuclear many body problem are discussed., Comment: Presented by RNP at the Erice School on Nuclear Physics 2011: From Quarks and Gluons to Hadrons and Nuclei, Erice, Sicily (Italy), 16-24 September 2011, 7 pages, 6 figures

We illustrate and discuss the role of meson-exchange currents in quasielastic neutrino-nucleus scattering induced by charged currents, comparing the results with the recent MiniBooNE data for differential and integrated cross sections., Comment: 9 pages, 8 figures; Proceedings of the 30th International Workshop on Nuclear Theory IWNT30, Rila Mountains, Bulgaria, June 27 - July 2, 2011

Two relativistic approaches to charged-current quasielastic neutrino-nucleus scattering are illustrated and compared: one is phenomenological and based on the superscaling behavior of electron scattering data and the other relies on the microscopic description of nuclear dynamics in relativistic mean field theory. The role of meson exchange currents in the two-particle two-hole sector is explored. The predictions of the models for differential and total cross sections are presented and compared with the MiniBooNE data., Comment: 3 pages, 3 figures, Proceedings of PANIC 2011, MIT, Cambridge, MA, July 2011

Two relativistic approaches are considered to evaluate the quasielastic double-differential and integrated neutrino-nucleus cross sections. One, based on the relativistic impulse approximation, relies on the microscopic description of nuclear dynamics using relativistic mean field theory, and incorporates a description of the final-state interactions. The second is based on the superscaling behavior exhibited by electron scattering data and its applicability, due to the universal character of the scaling function, to the analysis of neutrino scattering reactions. The role played by the vector meson-exchange currents in the two-particle two-hole sector is also incorporated and the results obtained are compared with the recent data for neutrinos measured by the MiniBooNE Collaboration., Comment: 17 page, 6 figures

Quasielastic double differential neutrino cross sections can be obtained in a phenomenological model based on the superscaling behavior of electron scattering data. In this talk the superscaling approach (SuSA) is reviewed and its validity is tested in a relativistic shell model. Results including meson exchange currents for the kinematics of the MiniBoone experiment are presented., Comment: Proceedings of XII International Workshop on Neutrino Factories, Superbeams and Betabeams (NuFact10), Tata Institute of Fundamental Research, Mumbai, India, 20-25 Oct. 2010

Heavy quark spin symmetry is discussed in the context of single and doubly heavy baryons. A special attention is paid to the constraints/simplifications that this symmetry imposes on the non-relativistic constituent quark model wave functions and on the b->c semileptonic decays of these hadrons., Comment: Presented at the 21st European Conference on Few-Body Problems in Physics, Salamanca, Spain, 30 August - 3 September 2010

We evaluate the quasielastic double differential neutrino cross sections obtained in a phenomenological model based on the superscaling behavior of electron scattering data. We compare our results with the recent experimental data for neutrinos of MiniBooNE and estimate the contribution of the vector meson-exchange currents in the 2p-2h sector., Comment: 6 pages, 4 figures

Two-particle two-hole contributions to electromagnetic response functions are computed in a fully relativistic Fermi gas model. All one-pion exchange diagrams that contribute to the scattering amplitude in perturbation theory are considered, including terms for pionic correlations and meson-exchange currents (MEC). The pionic correlation terms diverge in an infinite system and thus are regularized by modification of the nucleon propagator in the medium to take into account the finite size of the nucleus. The pionic correlation contributions are found to be of the same order of magnitude as the MEC., Comment: 14 pages, 15 figures

We describe a model for pion production off nucleons and coherent pions from nuclei induced by neutrinos in the 1 GeV energy regime. Besides the dominant Delta pole contribution, it takes into account the effect of background terms required by chiral symmetry. Moreover, the model uses a reduced nucleon-to-Delta resonance axial coupling, which leads to coherent pion production cross sections around a factor two smaller than most of the previous theoretical estimates. Nuclear effects like medium corrections on the Delta propagator and final pion distortion are included., Comment: 6 pages. To be published in the Proceedings of the Workshop on "Hadron and Nuclear Physics (HNP09)" Nov. 16-19, 2009, RCNP, Osaka University

We make a review of the main nuclear effects that affect neutrino-nucleus cross sections. We discuss how the different models in the literature try to describe these different effects, and thus try to compare between them. We focus on the quasi-elastic reaction in the neutrino energy region of around 1 GeV, where recent data from MiniBoone are available. Among the issues discussed are the different treatment of medium corrections to initial and nal state nucleon wave functions and the problem of the rescattering of ejected nucleons., Comment: 5 pages, 5 figures. To appear in the proceedings for NuFact09; July 20-25, (2009) Illinois Institute of Technology

We suggest that superscaling in electroweak interactions with nuclei, namely the observation that the reduced electron-nucleus cross sections are to a large degree independent of the momentum transfer and of the nuclear species, can be used as a tool to obtain precise predictions for neutrino-nucleus cross sections in both charged and neutral current-induced processes., Comment: 11 pages, 7 figures, proceedings of NUINT09, 6th International Workshop of Neutrino-Nucleus Interactions in the Few-Gev Region, Sitges (Spain), May 18-22, 2009

We review the general interplay between Nuclear Physics and neutrino-nucleus cross sections at intermediate and high energies. The effects of different reaction mechanisms over the neutrino observables are illustrated with examples in calculations using several nuclear models and ingredients., Comment: To appear in the proceedings of 6th International Workshop on Neutrino-Nucleus Interactions in the Few-GeV Region (NuInt09), Sitges, Spain, 18 - 22 May 2009

We present a microscopic model for neutrino induced one-pion production off the nucleon and its implementation for the purpose of calculating coherent pion production in nuclei. We further criticize the use of the Rein--Sehgal model for coherent pion production by low energy neutrinos. In particular, we show how the approximations in that model give rise to a much flatter differential cross section in the $\eta=E_\pi(1-\cos\theta_\pi)$ variable. We discuss the limitations intrinsic to any approach based on the partial conservation of the axial current hypothesis and the inability of such models to properly determine the angular distribution of the outgoing pion with respect to the direction of the incoming neutrino. We show the effects of those limitation for the case of the $\frac{d\sigma}{d\eta}$ differential cross section., Comment: Talk given at the NUINT09 Conference. 6 latex pages, 4 figures

The present study is focused on the superscaling behavior of electron-nucleus cross sections in the region lying above the quasielastic peak, especially the region dominated by electroexcitation of the Delta. Non-quasielastic cross sections are obtained from all available high-quality data for Carbon 12 by subtracting effective quasielastic cross sections based on the superscaling hypothesis. These residuals are then compared with results obtained within a scaling-based extension of the relativistic Fermi gas model, including an investigation of violations of scaling of the first kind in the region above the quasielastic peak. A way potentially to isolate effects related to meson-exchange currents by subtracting both impulsive quasielastic and impulsive inelastic contributions from the experimental cross sections is also presented., Comment: RevTeX, 34 pages including 11 figures

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 quasielastic peak. A semi-relativistic shell model is used for the one-particle-emission $(e,e')$ reaction. Relativistic effects are included using relativistic kinematics, performing a semi-relativistic 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 $q\geq 1$ 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., Comment: 4 pages, 5 figures

We present a microscopic model for coherent pion production off nuclei induced by neutrinos. This model is built upon a model for single nucleon processes that goes beyond the usual Delta dominance by including non resonant background contributions. We include nuclear medium effects: medium corrections to Delta$ properties and outgoing pion absortion via an optical potential. This results in major modifications to cross sections for low energy experiments when compared with phenomenological models like Rein-Sehgal's., Comment: 6 pages, 4 figures. Contribution to the proceedings of 45th Winter School in Theoretical Physics 'Neutrino Interactions: from Theory to Monte Carlo Simulations', Ladek-Zdroj, Poland, Feb. 2009

We have developed a model for neutrino-induced coherent pion production off nuclei in the energy regime of interest for present and forthcoming neutrino oscillation experiments. It is based on a microscopic model for pion production off the nucleon that, besides the dominant Delta pole contribution, takes into account the effect of background terms required by chiral symmetry. Moreover, the model uses a reduced nucleon-to-Delta resonance axial coupling, which leads to coherent pion production cross sections around a factor two smaller than most of the previous theoretical estimates. In the coherent production, the main nuclear effects, namely medium corrections on the Delta propagator and the final pion distortion, are included. We have improved on previous similar models by taking into account the nucleon motion and employing a more sophisticated optical potential. As found in previous calculations the modification of the Delta self-energy inside the nuclear medium strongly reduces the cross section, while the final pion distortion mainly shifts the peak position to lower pion energies. The angular distribution profiles are not much affected by nuclear effects. Nucleon motion increases the cross section by 15% at neutrino energies of 650 MeV, while Coulomb effects on charged pions are estimated to be small. Finally, we discuss at length the deficiencies of the Rein-Sehgal pion coherent production model for neutrino energies below 2 GeV, and in particular for the MiniBooNE and T2K experiments. We also predict flux averaged cross sections for these two latter experiments and K2K., Comment: 19 latex pages, 10 figures, 2 tables. Minor changes. Version accepted for publication in Physical Review D