20 research outputs found

    Forbidden transitions in neutral and charged current interactions between low-energy neutrinos and Argon

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    Background: The study of low-energy neutrinos and their interactions with atomic nuclei is crucial to several open problems in physics, including the neutrino mass hierarchy, CP-violation, candidates of Beyond Standard Model physics and supernova dynamics. Examples of experiments include CAPTAIN at SNS as well as DUNE's planned detection program of supernova neutrinos. Purpose: We present cross section calculations for quasielastic charged current and neutral current neutrinos at low energies, with a focus on 40^{40}Ar. We also take a close look at pion decay-at-rest neutrino spectra, which are used in e.g. the SNS experiment at Oakridge. Method and results: We employ a Hartree Fock + Continuum Random Phase Approximations (HF+CRPA) framework, which allows us to model the responses and include the effects of long-range correlations. It is expected to provide a good framework to calculate forbidden transitions, whose contribution which we show to be non-negligible. Conclusions: Forbidden transitions can be expected to contribute sizeably to the reaction strength at typical low-energy kinematics, such as DAR neutrinos. Modeling and Monte Carlo simulations need to take all due care to account for the influence of their contributions.Comment: 11 pages, 16 figures; minor corrections to v

    AA-dependence of quasielastic charged-current neutrino-nucleus cross sections

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    Background: 12C has been and is still widely used in neutrino-nucleus scattering and oscillation experiments. More recently, 40Ar has emerged as an important nuclear target for current and future experiments. Liquid argon time projection chambers (LArTPCs) possess various advantages in measuring electroweak neutrino-nucleus cross sections. Concurrent theoretical research is an evident necessity. Purpose: 40Ar is larger than 12C, and one expects nuclear effects to play a bigger role in reactions. We present inclusive differential and total cross section results for charged-current neutrino scattering on 40Ar and perform a comparison with 12C, 16O and 56Fe targets, to find out about the A-dependent behavior of model predictions. Method: Our model starts off with a Hartree-Fock description of the nucleus, with the nucleons interacting through a mean field generated by an effective Skyrme force. Long-range correlations are introduced by means of a continuum random phase approximation (CRPA) approach. Further methods to improve the accuracy of model predictions are also incorporated in the calculations. Results: We present calculations for 12C, 16O, 40Ar and 56Fe, showcasing differential cross sections over a broad range of kinematic values in the quasielastic regime. We furthermore show flux-folded results for 40Ar and we discuss the differences between nuclear responses. Conclusions: At low incoming energies and forward scattering we identify an enhancement in the 40Ar cross section compared to 12C, as well as in the high ω\omega (low TÎŒT_\mu ) region across the entire studied EÎœE_\nu range. The contribution to the folded cross section of the reaction strength at values of ω\omega lower than 50 MeV for forward scattering is sizeable.Comment: 9 pages, 8 figures ; complete revision of calculations with updated discussion of results, Fig. 4 replaced, updated reference list, minor typographical correction

    Lepton kinematics in low-energy neutrino-argon interactions

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    Background: Neutrinos in the low-energy regime provide a gateway to a wealth of interesting physics. While plenty of literature exists on detailing the calculation and measurement of total reaction strengths, relatively little attention is paid to the measurement and modeling of the final lepton through differential cross sections at low energies, despite the experimental importance. Purpose: We calculate differential cross sections for low-energy neutrino-nucleus scattering. We examine the role played by forbidden transitions in these distributions and how this differs across different energies and nuclear target masses. Attention is also paid to predictions for typical experimental neutrino spectra. Method: The differential cross sections are calculated within a continuum random-phase approximation framework, which allows us to include collective excitations induced by long-range correlations. The Coulomb interaction of the final lepton in charged current events is treated in an effective way. Results: Kinematic distributions are calculated for O-16, Ar-40, and Pb-208. The Ar-40 model results are compared for charged current (CC) (nu(e), e(-)) reactions to events generated by the Modeling of Argon Reaction Low-energy Yields (MARLEY) event generator [S. Gardiner, Ph.D. thesis, University of California, Davis (2018)], with noticeable discrepancies. Conclusion: Forbidden transitions have a marked effect on the kinematic distributions of the final lepton at low-energy kinematics, such as for decay-at-rest neutrinos or for a Fermi-Dirac spectrum at low temperature. This could introduce biases in experimental analyses. Backward scattering is noticeably more prominent than with MARLEY

    CRPA calculations for neutrino-nucleus scattering : from very low energies to the quasielastic peak

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    International audienceWe present continuum random phase approximation calculations (CRPA) for neutrino-induced quasielastic scattering off atomic nuclei. The validity of our formalism is checked by a careful confrontation of its results with semi-inclusive double-differential electron scattering data. We pay special attention to excitations in the giant resonance region. The CRPA is well-suited for the description of interactions in this energy range. We aim at providing a uniform description of one-nucleon knockout processes over the whole energy range from threshold to the quasielastic peak. Our calculations point to the fact that low-energy and giant-resonance excitations provide a non-negligible contribution to the interaction strength, especially at forward lepton-scattering angles

    Influence of short-range correlations in neutrino-nucleus scattering

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    Background: Nuclear short-range correlations (SRCs) are corrections to mean-field wave functions connected with the short-distance behavior of the nucleon-nucleon interaction. These SRCs provide corrections to lepton- nucleus cross sections as computed in the impulse approximation (IA). Purpose: We want to investigate the influence of SRCs on the one-nucleon (1N) and two-nucleon (2N) knockout channel for muon-neutrino induced processes on a 12^{12}C target at energies relevant for contemporary measurements. Method: The model adopted in this work, corrects the impulse approximation for SRCs by shifting the com- plexity induced by the SRCs from the wave functions to the operators. Due to the local character of the SRCs, it is argued that the expansion of these operators can be truncated at a low order. Results: The model is compared with electron-scattering data, and two-particle two-hole responses are presented for neutrino scattering. The contributions from the vector and axial-vector parts of the nuclear current as well as the central, tensor and spin-isospin part of the SRCs are studied. Conclusions: Nuclear SRCs affect the 1N knockout channel and give rise to 2N knockout. The exclusive neutrino-induced 2N knockout cross section of SRC pairs is shown and the 2N knockout contribution to the QE signal is calculated. The strength occurs as a broad background which extends into the dip region.Comment: 16 pages, 10 figures. Version published in Physical Review

    Correlations in neutrino-nucleus scattering

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    We present a detailed study of charged-current quasielastic neutrino-nucleus scattering and of the influence of correlations on one- and two-nucleon knockout processes. The quasielastic neutrino-nucleus scattering cross sections, including the influence of long-range correlations, are evaluated within a continuum random phase approximation approach. The short-range correlation formalism is implemented in the impulse approximation by shifting the complexity induced by the correlations from the wave functions to the operators. The model is validated by confronting (e,eâ€Č)(e,e^\prime) cross-section predictions with electron scattering data in the kinematic region where the quasielastic channel is expected to dominate. Further, the 12^{12}C(Îœ,Ό−)(\nu,\mu^-) experiments are studied. Double differential cross sections relevant for neutrino-oscillation 12^{12}C(Îœ,Ό−)(\nu,\mu^-) cross sections, accounting for long- and short-range correlations in the one-particle emission channel and short-range correlations in the two-particle two-hole channel, are presented for kinematics relevant for recent neutrino-nucleus scattering measurements.Comment: 10 pages, 4 figures. Contribution to the proceedings of the 17th International Workshop on Neutrino Factories and Future Neutrino Beam Facilities (NUFACT-2015

    Electron versus muon neutrino induced cross sections in charged current quasi-elastic processes

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    Differences between Μe\nu_e and ΜΌ\nu_{\mu} quasielastic cross sections are essential in neutrino oscillation analyses and CP violation searches for experiments such as DUNE and T2HK. The ratio of these is however poorly known experimentally and for certain kinematic regions theoretical models give contradictory answers. We use two independent mean-field based models to investigate this ratio using 40^{40}Ar and 12^{12}C targets. We demonstrate that a proper treatment of the final nucleon's wave function confirms the dominance of ΜΌ\nu_{\mu} over Μe\nu_e induced cross sections at forward lepton scattering.Comment: Updated Fig. 2, minor changes to text, accepted for publication in Phys. Rev. Letter

    Neutrino-Induced 1-π Production

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    Neutrino-induced pion production constitutes an important contribution to neutrino-nucleus scattering cross sections at intermediate energies. A deep understanding of this process is mandatory for a correct interpretation of neutrino-oscillation experiments. We aim at contributing to the ongoing effort to understand the various experimental results obtained by different collaborations in a wide range of energies. In particular, in this work we analyze recent MiniBooNE and MINERvA charged-current neutrino 1-pion production data. We use a relativistic theoretical approach which accounts for resonant and non-resonant 1-pion production contributions
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