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 se
rve 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 Minerva and Nova experiments are made.
Neutrino oscillation probabilities, which are being measured in long-baseline experiments, depend on neutrino energy. The energy in a neutrino beam, however, is broadly smeared so that the neutrino energy in a particular event is not directly known,
but must be reconstructed from final state properties. In this paper we investigate the contributions from different reaction mechanisms on the energy-reconstruction method widely used in long-baseline neutrino experiments. Difference between the true-QE and QE-like cross sections in MiniBooNE experiment is investigated in details. It is shown, that fake QE-like events lead to significant distortions in neutrino energy reconstruction. Flux-folded and unfolded cross sections for QE-like scattering are calculated as functions of both true and reconstructed energies. Flux-folded momentum transfer distributions are calculated as functions of both true and reconstructed momentum transfer. Distributions versus reconstructed values are compared with the experimental data. Also presented are the conditional probability densities of finding a true energy for a given reconstructed energy. It is shown, how the energy reconstruction procedure influences the measurement of oscillation parameters in T2K experiment. For the reconstruction procedure based on quasielastic (QE) kinematics, all other reaction channels beside true-QE scattering show a shift of the reconstructed energy towards lower values as compared to the true energy. On average in the MiniBooNE and T2K experiments the shift is 100 - 200 MeV and depends on energy. The oscillation signals are similarly affected. These uncertainties may limit the extraction of a CP violating phase from an oscillation result.
Background: Nuclear effects can have a significant impact on neutrino-nucleus interactions. In particular, data from neutrino experiments with broad energy distributions require complex theoretical models that are able to take all the relevant channe
ls into account as well as incorporate nuclear effects in both initial and final-state interactions. Purpose: We investigate neutrino and antineutrino scattering on iron and carbon in the energy range from 1 to 30 GeV, which is relevant to current and coming experiments (MINOS, NOvA, and Minerva). Method: The Giessen Boltzmann--Uehling--Uhlenbeck (GiBUU) model, which implements all reaction channels relevant for neutrino energies under consideration, is used for an investigation of neutrino-nucleus reactions. Results: Our calculations are compared with the recent NOMAD and MINOS data for the integrated inclusive cross sections. Predictions are made for the differential cross sections for semiinclusive final states (pions, kaons, and nucleons) for the MINOS and NOvA beams. Conclusions: Nuclear effects in the initial-state interactions may slightly change the inclusive nuclear cross section as compared to the free nucleon ones. Final-state interactions noticeably change the spectra of the outgoing hadrons. In the Minerva and NOvA experiments these effects should be visible in the kinetic energy distributions of the final pions, kaons, and nucleons. Secondary interactions play an important role for strangeness production.
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 s
hown, that final state interaction can noticeably change the spectra of the outgoing hadrons. Predictions for the Miner$ u$a experiment are made for pion spectra, averaged over NuMI neutrino and antineutrino fluxes.
We investigate one pion production processes within the Giessen Boltzmann--Uehling--Uhlenbeck (GiBUU) coupled channel transport model. Our calculations for integrated and differential cross sections for realistic experimental neutrino fluxes are comp
ared to the data recently provided by the MiniBooNE collaboration.
The GiBUU model, which implements all reaction channels relevant at medium neutrino energy, is used to investigate the neutrino and antineutrino scattering on iron. Results for integrated cross sections are compared with NOMAD and MINOS data. It is s
hown, that final state interaction can noticeably change the spectra of the outgoing hadrons. Predictions for the Miner$ u$a experiment are made for pion spectra, averaged over NuMI neutrino and antineutrino fluxes.
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 methods 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 $1 pi$ production are closely entangled in actual experiments, due to final state interactions of the scattered nucleons on one hand and of the $Delta$ 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 $1 pi$ 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 $F_2$ 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.
We present a fully relativistic formalism for describing neutrino-induced $Delta$-mediated single-pion production from nuclei. We assess the ambiguities stemming from the $Delta$ interactions. Variations in the cross sections of over 10% are observed
, depending on whether or not magnetic-dipole dominance is assumed to extract the vector form factors. These uncertainties have a direct impact on the accuracy with which the axial-vector form factors can be extracted. Different predictions for $C_5^A(Q^2)$ induce up to 40-50% effects on the $Delta$-production cross sections. To describe the nucleus, we turn to a relativistic plane-wave impulse approximation (RPWIA) using realistic bound-state wave functions derived in the Hartree approximation to the $sigma$-$omega$ Walecka model. For neutrino energies larger than 1 GeV, we show that a relativistic Fermi-gas model with appropriate binding-energy correction produces comparable results as the RPWIA which naturally includes Fermi motion, nuclear-binding effects and the Pauli exclusion principle. Including $Delta$ medium modifications yields a 20 to 25% reduction of the RPWIA cross section. The model presented in this work can be naturally extended to include the effect of final-state interactions in a relativistic and quantum-mechanical way. Guided by recent neutrino-oscillation experiments, such as MiniBooNE and K2K, and future efforts like MINER$ u$A, we present $Q^2$, $W$, and various semi-inclusive distributions, both for a free nucleon and carbon, oxygen and iron targets.
We present a relativistic model for electroweak pion production from nuclei, focusing on the $Delta$ and the second resonance region. Bound states are derived in the Hartree approximation to the $sigma-omega$ Walecka model. Final-state interactions o
f the outgoing pion and nucleon are described in a factorized way by means of a relativistic extension of the Glauber model. Our formalism allows a detailed study of neutrino pion production through $Q^2$, $W$, energy, angle and out-of-plane distributions.
