Charged-current Neutrino-nucleus Reactions Research Articles

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 relativis- tic 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 electron- nucleus 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.

Neutrino-nucleus CCQE-like scattering

RPA correlations, spectral function and 2p2h (multi-nucleon) effects on charged-current neutrino-nucleus reactions without emitted pions are discussed. We pay attention to the influence of RPA and multi-nucleon mechanisms on the MiniBooNE and MINERvA flux folded differential cross sections, the MiniBooNE flux unfolded total cross section and the neutrino energy reconstruction.

Modeling nuclear weak-interaction processes with relativistic energy density functionals

Relativistic energy density functionals have become a standard framework for nuclear structure studies of ground state properties and collective excitations over the entire nuclide chart. In this paper, we review recent developments in modeling nuclear weak-interaction processes: Charge-exchange excitations and the role of isoscalar proton–neutron pairing, charged-current neutrino–nucleus reactions relevant for supernova evolution and neutrino detectors and calculation of β-decay rates for r-process nucleosynthesis.

Graphical imaging system for shifted spectrum in daughter nuclei of charged-current v-nucleus reactions

In this work, we improve the automated algorithm derived previously for drawing the quantum energy levels, in order to be efficient for plotting the theoretical spectra of the daughter nuclei in charged-current neutrino-nucleus reactions. Such calculated spectra need to be shifted so as the charged-current transition energies to be measured from the ground state of the daughter nucleus. The improvement involves the development of a computational code and graphical imaging system able to treat appropriately and as accurate as possible the energy-shifting which is different for the various multipole sets of nuclear states. The method is applied in the case of antineutrino-nucleus reaction which is of current experimental interest.

Detailed description of exclusive muon capture rates using realistic two-body forces

Starting from state-by-state calculations of exclusive rates of the ordinary muon capture (OMC), we evaluated total muon-capture rates for a set of light- and medium-weight nuclear isotopes. We employed a version of the proton-neutron quasi-particle random phase approximation (pn-QRPA, for short) which uses as realistic nuclear forces the Bonn C-D one boson exchange potential. Special attention was paid on the percentage contribution to the total muon-capture rate of specific low-spin multipolarities resulting by summing over the corresponding multipole transitions. The nuclear method used offers the possibility of estimating separately the individual contributions to the total and partial rates of the polar-vector and axial-vector components of the weak interaction Hamiltonian for each accessible final state of the daughter nucleus. One of our main goals is to provide a reliable description of the charge changing transitions matrix elements entering the description of other similar semileptonic nuclear processes like the charged-current neutrino-nucleus reactions, the electron capture on nuclei, the single \b{eta}-decay mode, etc., which play important role in currently interesting laboratory and astrophysical applications like the neutrino-detection through lepton- nucleus interaction probes, and neutrino-nucleosynthesis. Such results can be also be useful in various ongoing muon-capture experiments at PSI, Fermilab, JPARC and RCNP.

Semi-inclusive charged-current neutrino-nucleus reactions

The general, universal formalism for semi-inclusive charged-current (anti)neutrino-nucleus reactions is given for studies of any hadronic system, namely, either nuclei or the nucleon itself. The detailed developments are presented with the former in mind and are further specialized to cases where the final-state charged lepton and an ejected nucleon are presumed to be detected. General kinematics for such processes are summarized and then explicit expressions are developed for the leptonic and hadronic tensors involved and for the corresponding responses according to the usual charge, longitudinal and transverse projections, keeping finite the masses of all particles involved. In the case of the hadronic responses, general symmetry principles are invoked to determine which contributions can occur. Finally, the general leptonic-hadronic tensor contraction is given as well as the cross section for the process.

Neutrino-nucleus quasi-elastic and 2p2h interactions up to 10 GeV

We extend to 10 GeV results from a microscopic calculation of charged-current neutrino-nucleus reactions that do not produce a pion in the final state. For the class of events coming from neutrino interactions with two nucleons producing two holes (2p2h), limiting the calculation to three-momentum transfers less than 1.2 GeV produces a two dimensional distribution in momentum and energy transfer that is roughly constant as a function of energy. The cross section for 2p2h interactions scales with the number of nucleons for isoscalar nuclei, similar to the quasi-elastic (QE) cross section. When limited to momentum transfers below 1.2 GeV, the cross section is 26% of the QE cross section at 3 GeV, but 14% if we neglect a Delta1232 resonance absorption component. The same quantities are 33% and 17% for anti-neutrinos. For the quasi-elastic interactions, the full nuclear model with long range correlations produces an even larger, but approximately constant distortion of the shape of the four-momentum transfer at all energies above 2 GeV. The 2p2h enhancement and long-range correlation distortions to the cross section for these interactions is significant enough they should be observable in precision experiments to measure neutrino oscillations and neutrino interactions at these energies, but also balance out and produce less total distortion than each effect does individually.

Supernova neutrino reactions on 114Cd and 116Cd isotopes via charge current interaction

Neutrinos and their interactions with nuclei have attracted a great deal of attention, since they play a fundamental role in nuclear physics, cosmology and various astrophysical processes, especially in the dynamics of core-collapse supernova-nucleosynthesis. Since there are very few experimental data available on charged current neutrino–nucleus reactions, modelling these provides the relevant input for supernova simulations. In this work, the total cross sections as well as the neutrino event rates are calculated in the charge current neutrino and antineutrino scattering off 114Cd and 116Cd isotopes at neutrino energies Eν < 100 MeV. These isotopes are the contents of several detectors of ongoing experiments with multiple neutrino physics goals. Such cross section calculations provide us with significant information regarding the range of efficiency of these isotopes in low-energy neutrino searches. Transitions to excited nuclear states are calculated in the framework of a quasiparticle random-phase approximation. The contributions from different multipoles are shown for various neutrino energies. Flux-averaged cross sections are obtained by convolving the cross sections with the Fermi–Dirac distribution of supernova neutrinos.

Inclusive charged-current neutrino-nucleus reactions

We present a model for weak charged-current induced nuclear reactions at energies of interest for current and future neutrino oscillation experiments. This model is a natural extension of the work in Refs. [1,2], where the quasielastic contribution to the inclusive electron and neutrino scattering on nuclei was analyzed. The model is based on a systematic many-body expansion of the gauge boson absorption modes that includes one, two, and even three-body mechanisms, as well as the excitation of $\ensuremath{\Delta}$ isobars. The whole scheme has no free parameters, besides those previously adjusted to the weak pion production off the nucleon cross sections in the deuteron, since all nuclear effects were set up in previous studies of photon, electron, and pion interactions with nuclei. We have discussed at length the recent charged-current quasielastic MiniBooNE cross section data, and showed that two-nucleon knockout mechanisms are essential to describing these measurements.

Inclusive charged-current neutrino-nucleus reactions calculated with the relativistic quasiparticle random-phase approximation

Inclusive neutrino-nucleus cross sections are calculated using a consistent relativistic mean-field theoretical framework. The weak lepton-hadron interaction is expressed in the standard current-current form, the nuclear ground state is described with the relativistic Hartree-Bogoliubov model, and the relevant transitions to excited nuclear states are calculated in the relativistic quasiparticle random phase approximation. Illustrative test calculations are performed for charged-current neutrino reactions on $^{12}$C, $^{16}$O, $^{56}$Fe, and $^{208}$Pb, and results compared with previous studies and available data. Using the experimental neutrino fluxes, the averaged cross sections are evaluated for nuclei of interest for neutrino detectors. We analyze the total neutrino-nucleus cross sections, and the evolution of the contribution of the different multipole excitations as a function of neutrino energy. The cross sections for reactions of supernova neutrinos on $^{16}$O and $^{208}$Pb target nuclei are analyzed as functions of the temperature and chemical potential.

Theoretical uncertainties on quasielastic charged-current neutrino–nucleus cross sections

We estimate the theoretical uncertainties of the model developed in [J. Nieves, J.E. Amaro, M. Valverde, Phys. Rev. C 70 (2004) 055503] for inclusive quasielastic charged-current neutrino–nucleus reactions at intermediate energies. Besides we quantify the deviations of the predictions of this many body framework from those obtained within a simple Fermi gas model. A special attention has been paid to the ratio σ ( μ ) / σ ( e ) of interest for experiments on atmospheric neutrinos. We show that uncertainties affecting this ratio are likely smaller than 5%.

Superscaling in Charged Current Neutrino Quasielastic Scattering in the Relativistic Impulse Approximation

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.

Erratum: Inclusive quasielastic charged-current neutrino-nucleus reactions [Phys. Rev. C 70, 055503 (2004)

The Quasi-Elastic (QE) contribution of the nuclear inclusive electron scattering model developed in Nucl. Phys. A627 (1997) 543 is extended to the study of electroweak Charged Current (CC) induced nuclear reactions, at intermediate energies of interest for future neutrino oscillation experiments. The model accounts for, among other nuclear effects, long range nuclear (RPA) correlations, Final State Interaction (FSI) and Coulomb corrections. Predictions for the inclusive muon capture in $^{12}$C and the reaction $^{12}$C $(\nu_\mu,\mu^-)X$ near threshold are also given. RPA correlations are shown to play a crucial role and their inclusion leads to one of the best existing simultaneous description of both processes, with accuracies of the order of 10-15% per cent for the muon capture rate and even better for the LSND measurement.

Magnetic dipole and Gamow–Teller modes: quenching, fine structure and astrophysical implications

The magnetic dipole (M1) and Gamow–Teller (GT) response are prime examples to illustrate the importance of configuration mixing for an understanding of elementary excitation modes of the nucleus. Starting from the ’’classical’’ problem of quenching - whose proper description is still beyond the capabilities of microscopic models after all those years — I want to address some current developments of the field. Mandatory for the progress are high-resolution data from electron and hadron scattering and charge-exchange reactions.In medium-mass fp-shell nuclei, the detailed knowledge of the M1 and GT strength distribution provides a stringent test of state-of-the-art shell-model calculations, validating their applicability in astrophysical network calculations. As an example, it is demonstrated that high-precision M1 data on N = 28 isotones from electron scattering at Darmstadt permit the extraction of neutral-current neutrino-nucleus scattering cross sections important for supernova dynamics and nucleosynthesis.Fine structure of the GT mode is not only observed in light and medium-mass nuclei, but also in the GT resonance observed in a heavy nucleus like 90Nb studied in the 90Zr(3He, t) reaction at Osaka with a resolution ΔE ≃ 50 keV (FWHM). Novel methods, based on wavelet transforms, to extract scales characterizing the fine structure are presented. This in turn permits an interpretation of the physics underlying the phenomenon. These methods can also be used to extract spin- and parity-resolved level densities in a nearly model-independent way, again important to test models used in various astrophysical scenarios.As a final example, the influence of configuration mixing on the GT strength distribution at low energies is investigated for the heavy odd-odd nuclei 138La and 180Ta. The nucleosynthesis of these exotic nuclides, amongst the rarest in nature, is a long-standing problem. A likely source are charged-current neutrino-nucleus reactions which would be dominated by the GT response. However, the main GT resonance lies above the particle threshold and, therefore, does not contribute. Recent measurements of the GT strength distributions in 138La and 180Ta below the particle threshold and their astrophysical implications are discussed.

Inclusive quasielastic charged-current neutrino-nucleus reactions

The quasielastic (QE) contribution of the nuclear inclusive electron scattering model developed by Gil, Nieves, and Oset [Nucl. Phys. A627, 543 (1997); A627, 599 (1997)] is extended to the study of electroweak charged current (CC) induced nuclear reactions, at intermediate energies of interest for future neutrino oscillation experiments. The model accounts for, among other nuclear effects, long range nuclear [random phase approximation (RPA)] correlations, final state interaction (FSI), and Coulomb corrections. Predictions for the inclusive muon capture in $^{12}\mathrm{C}$ and the reaction $^{12}\mathrm{C}$ $({\ensuremath{\nu}}_{\ensuremath{\mu}},{\ensuremath{\mu}}^{\ensuremath{-}})X$ near threshold are also given. RPA correlations are shown to play a crucial role and their inclusion leads to one of the best existing simultaneous description of both processes, with accuracies of the order of 10\char21{}15 % for the muon capture rate and even better for the Liquid Scintillating Neutrino Detector (LSND) measurement.

“Subthreshold” reactions involving nuclear fission

We analyze reactions of several types that are naively below threshold but can proceed because of the release of binding energy from nuclear fission and occasionally the formation of Coulombic bound states. These reactions include (i) photofission with pion production and (ii) charged current neutrino-nucleus reactions that lead to fission and/or formation of a Coulomb bound state of a $\mu^-$ with the nucleus of a fission fragment. We comment on the possible experimental observation of these reactions.