Search

Background: Neutrino-induced pion production can give important informationon the axial coupling to nucleon resonances. Furthermore, pion production represents a major background to quasielastic-like events. one pion production data from the MiniBooNE in charged current neutrino scattering in mineral oil appeared higher than expected within conventional theoretical approaches. Purpose: We aim to investigate which model parameters affect the calculated cross section and how they do this. Method: The Giessen Boltzmann-Uehling-Uhlenbeck (GiBUU) model is used for an investigation of neutrino-nucleus reactions. Results: Presented are integrated and differential cross sections for 1π+ and 1π0 production before and after final state interactions in comparison with the MiniBooNE data. Conclusions: For the MiniBooNE flux all processes (QE, 1π-background, Δ, higher resonance production, DIS) contribute to the observed final state with one pion of a given charge. The uncertainty in elementary pion production cross sections leads to a corresponding uncertainty in the nuclear cross sections. Final state interactions change the shape of the muon-related observables only slightly, but they significantly change the shape of pion distributions. [ABSTRACT FROM AUTHOR]

In this talk we shortly describe the physics contents of the GiBUU transport code, used to describe lepton scattering off nuclei. Particular attention will be given to validation of the GiBUU in pion-, electron- and photon-induced reactions, which serve as a benchmark for neutrino-induced ones. We mainly concentrate on those properties of benchmark reactions, which are relevant to the region of Shallow Inelastic Scattering (SIS). Our results in this region are presented for integrated and differential cross sections. Comparison with recent MINOS inclusive data, as well as predictions for the differential cross sections measurable in Minern a and NonA experiments are made. [ABSTRACT FROM AUTHOR]

The reactions (γ/π)→γN, πN, 2πN, ηN, KΛ, KSigma, ωN are simultaneously analysed within a coupled-channel unitary Lagrangian approach (Giessen Model). The resonance contributions to the different transition channels are shown and discussed. The results for ηN and KΛ, final states in both pion- and photo-induced reactions are presented in more details in prospect of new experimental data from MAMI and CLAS. The recent progress in the description of the 2πN channel in terms of the πN→ρN, σN, πΔ transitions is presented. [ABSTRACT FROM AUTHOR]

We investigate one pion production processes within the Giessen Boltzmann-Uehling-Uhlenbeck (GiBUU) coupled channel transport model. Our calculations for integrated and differential cross sections for realistic experimental neutrino fluxes are compared to the data recently provided by the MiniBooNE collaboration. [ABSTRACT FROM AUTHOR]

The GiBUU model, which implements all reaction channels relevant at medium neutrino energy, is used to investigate the neutrino and antineutrino scattering on iron. Results for integrated cross sections are compared with NOMAD and MINOS data. It is shown, that final state interaction can noticeably change the spectra of the outgoing hadrons. Predictions for the Minerνa experiment are made for pion spectra, averaged over NuMI neutrino and antineutrino fluxes. [ABSTRACT FROM AUTHOR]

Neutrino-induced pion production on nuclear targets is the major inelastic channel in all present-day neutrino-oscillation experiments. It has to be understood quantitatively in order to be able to reconstruct the neutrino-energy at experiments such as MiniBooNE or K2K and T2K. We report here results of cross section calculations for both this channel and for quasielastic scattering within the semiclassical GiBUU method. This method contains scattering, both elastic and inelastic, absorption and side-feeding of channels all in a unitary, common theoretical framework and code. We find that charged current quasielastic scattering (CCQE) and 1 π production are closely entangled in actual experiments, due to final state interactions of the scattered nucleons on one hand and of the Δ resonances and pions, on the other hand. We discuss the uncertainties in the elementary pion production cross sections from ANL and BNL. We find the surprising result that the recent 1 π production cross section data from MiniBooNE are well described by calculations without any FSI. For higher energies we study the validity of the Bloom-Gilman quark-hadron duality for both electron- and neutrino-induced reactions. While this duality holds quite well for nucleon targets, for nuclear targets the average resonance contributions to the structure function F2 are always lower than the DIS values. This result indicates a significant impact of nuclear effects on observables, reducing the cross section and structure functions by at least 30–40% and changing the form of various distributions. [ABSTRACT FROM AUTHOR]

All available theoretical estimates of neutrino-induced coherent pion production rely on the ‘local approximation’ for the Delta propagator. The validity of this approximation is scrutinized. It is found that the local approximation overestimates the neutrino-induced coherent pion production on nuclei significantly, by up to 100%. [ABSTRACT FROM AUTHOR]

We present our description of neutrino induced charged current quasielastic scattering (CCQE) in nuclei at energies relevant for the MiniBooNE experiment. In our framework, the nucleons, with initial momentum distributions according to the Local Fermi Gas model, move in a density- and momentum-dependent mean field potential. The broadening of the outgoing nucleons due to nucleon-nucleon interactions is taken into account by spectral functions. Long range (RPA) correlations renormalizing the electroweak strength in the medium are also incorporated. The background from resonance excitation events that do not lead to pions in the final state is also predicted by propagating the outgoing hadrons with the Giessen semiclassical BUU model in coupled channels (GiBUU). We achieve a good description of the shape of the CCQE Q2 distribution extracted from data by MiniBooNE, thanks to the inclusion of RPA correlations, but underestimate the integrated cross section when the standard value of MA = 1 GeV is used. Possible reasons for this mismatch are discussed. [ABSTRACT FROM AUTHOR]

We investigate charged and neutral current neutrino-induced incoherent pion production off nuclei within the GiBUU model at energies relevant for the MiniBooNE and K2K experiments. Special attention is paid to the entanglement between measured CCQE and CC1π+ cross sections. We further give predictions and compare to recent data measured at MiniBooNE. [ABSTRACT FROM AUTHOR]

A phenomenological study of Bloom-Gilman duality is performed in electron and neutrino scattering on nuclei. In the resonance region the structure functions are calculated within the phenomenological models of Ghent and Giessen groups, where only the resonance contribution is taken into account, and the background one is neglected. Structure functions F2 in the resonance region are compared with the DIS ones, extracted directly from the experimental data. The results show, that within the models considered the Bloom-Gilman duality does not work well for nuclei: the integrated strength in the resonance region is considerably lower than in the DIS one. [ABSTRACT FROM AUTHOR]

We investigate neutrino-nucleus collisions at intermediate energies incorporating quasielastic scattering and the excitation of 13 resonances as elementary processes, taking into account medium effects such as Fermi motion, Pauli blocking, mean-field potentials and in-medium spectral functions. A coupled-channel treatment of final state interactions is achieved with the GiBUU transport model. Results for inclusive reactions, neutrino- and electron-induced, as well as for pion production and nucleon knockout are presented. [ABSTRACT FROM AUTHOR]

We have investigated the neutrino induced coherent pion production reaction at the energies of interest for recent experiments like K2K and MiniBooNE. The model includes pion, nucleon and the Δ(1232) resonance. Medium effects in the production mechanism and the distortion of the pion wave function are taken into account. We find a strong reduction of the cross section due to these effects and also substantial modifications in the energy distributions of the final pion. The sensitivity of the results on the axial N-Δ coupling C5A(0) and the coherent fraction in neutral-current π0 production are discussed. [ABSTRACT FROM AUTHOR]

We predict the triple differential cross section of the unpolarized Drell-Yan process at √S ?? 6 GeV. The model incorporates primordial parton transverse momentum and quark offshellness effects caused by the initial state interaction. [ABSTRACT FROM AUTHOR]

The pion-induced reactions are studied within a unitary coupled-channel effective La-grangian model to obtain information on the baryon resonance spectra in up to 2 GeV energy region. We extend our previous calculations to include spin-5⁄2 resonance contributions. The effects of the spin-5⁄2 contributions to the different open channels are discussed. [ABSTRACT FROM AUTHOR]

We investigate meson electroproduction off complex nuclei in the kinematic regime of the HERMES experiment using a semi-classical transport model which is based on the Boltzmann­Uehling­Uhlenbeck (BUU) equation. We discuss coherence length and color transparency effects in exclusive ρ0 production as well as hadron formation and attenuation of charged pions, kaons, protons and anti-protons in deep inelastic lepton scattering off nuclei. [ABSTRACT FROM AUTHOR]

The Giessen BUU transport approach applied to electroweak interactions on nuclei in the few-GeV region is presented. After describing the model ingredients (elementary cross sections, medium effects and final state interactions), the impact of nuclear effects on the observables is discussed. We emphasize the interconnection of quasielastic and pion production processes, which receive a unified treatment, and its relevance for present neutrino experiments. [ABSTRACT FROM AUTHOR]

We investigate neutrino-nucleus collisions at intermediate energies incorporating quasielastic scattering and Δ(1232) excitation as elementary processes, together with Fermi motion, Pauli blocking and mean-field potentials in the nuclear medium. A full coupled-channel treatment of final state interactions is achieved with a semiclassical BUU transport model. Results for inclusive reactions and nucleon knockout are presented. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

We present a transport theoretical analysis of hadron attenuation in deep inelastic lepton scattering (DIS) off complex nuclei in the kinematic regime of the HERMES experiment. The HERMES data indicate the presence of strong prehadronic final state interactions shortly after the elementary lepton-nucleon interaction. The contribution of such (pre-)hadronic final state interactions to the observed jet quenching in ultra-relaticistic heavy ion collisions (HIC) at RHIC is estimated under the assumption that a similar space-time picture for hadronization also holds in a hot hadronic medium. Our results show that an additional mechanism for jet quenching must be at work for most central collisions. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]