Engineering topics
Publications and source records attributed to Mosel, U.
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.
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 Miner{nu}a experiment are made for pion spectra, averaged over NuMI neutrino and antineutrino fluxes.
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.
Ongoing experiments at JLAB investigate the nuclear transparency in exclusive {rho}{sup 0}(770) electroproduction off nuclei. In this work we present transport model predictions for the attenuation of {rho}{sup 0}s in nuclei and for color transparency (CT) effects as observable at CLAS with a 5 GeV electron beam energy. A full event simulation developed here permits to study the impact of actual experimental acceptance conditions and kinematical cuts. The exclusive (e,e{sup '{rho}0}) cross section off nucleons is described by diffractive and color string breaking mechanisms extended toward the onset of the deep inelastic regime. Different hadronization and CT scenarios are compared. We show that a detailed analysis of the elementary cross section, nuclear effects, and experimental cuts is needed to reveal the early onset of {rho}-CT at present JLAB energies.
We investigate the pp{yields}ppe{sup +}e{sup -} and quasifree pn{yields}pne{sup +}e{sup -} reactions within an effective Lagrangian model at a laboratory kinetic energy of 1.25 GeV for which experimental data have recently been reported by the HADES Collaboration. The model uses a meson-exchange approximation to describe the initial nucleon-nucleon (NN) scattering. Contributions to the reaction amplitudes are included from the NN bremsstrahlung as well as from the excitation, propagation, and radiative decay of the {Delta}(1230) isobar state. It is found that the HADES data on the e{sup +}e{sup -} invariant mass distribution in the pp{yields}ppe{sup +}e{sup -} reaction are excellently reproduced by our model where the {Delta} isobar term dominates the spectrum. In the case of the quasifree pn{yields}pne{sup +}e{sup -} reaction, a strong sensitivity to the pion electromagnetic form factor is observed which helps to bring the calculated cross sections closer to the data in the higher dilepton mass region.
We investigate neutrino-induced one pion production on nucleons. The elementary neutrino-nucleon cross section is calculated as the sum of the leading Delta pole diagram and several background diagrams obtained within the nonlinear sigma model. This approach does not introduce any new adjustable parameters, which allows unambiguous predictions for the observables. Considering electroproduction experiments as benchmark, the model is shown to be applicable up to pion-nucleon invariant mass W<1.4 GeV and provides a good accuracy. With respect to the total one pion cross section, the model predicts the background at the level of 10% for the p{pi}{sup +}, 30% for p{pi}{sup 0}, and 50% for n{pi}{sup +} final states. The results are compared with experimental data for various differential cross sections. Distributions with respect to muon-nucleon and muon-pion invariant masses are presented for the first time. The model describes the data quite well, with the discrepancies being of the same order as those between different data sets.
We present a study of neutrino-nucleus interactions at the T2K experiment based on the GiBUU transport model. The aim of T2K is to measure {nu}{sub e} appearance and {theta}{sub 13}, but it will also be able to do a precise measurement of {nu}{sub {mu}}disappearance. The former requires a good understanding of {pi}{sup 0} production, while the latter is closely connected with a good understanding of quasielastic scattering. For both processes we investigate the influence of nuclear effects and particular final-state interactions on the expected event rates, taking into account the T2K detector setup.
We show that the Lagrangian of a free spin-(5/2) field in the spinor-tensor representation with an auxiliary spinor field depends on three arbitrary parameters. The first two parameters are associated with the spin-(3/2) and spin-(1/2) sector of the theory while the last is related to the auxiliary degrees of freedom. We derive a corresponding propagator of the system which represents a (2x2) matrix in the (psi{sub m}u{sub n}u,xi) space. The diagonal terms stand for the propagation of the spin-(5/2) and auxiliary fields whereas the nondiagonal ones correspond to the psi{sub m}u{sub n}u-xi mixing. The resulting spin-(5/2) propagator contains nonpole contributions coming from the spin-(3/2) and spin-(1/2) sector of the spinor-tensor representation. A general form of the interaction vertex involving the spin-(5/2) field is discussed by the example of the piNN{sub (5/2)}* coupling. It is demonstrated that lower spin degrees of freedom can be removed from the theory by use of higher-order derivative coupling.
We apply the Giessen Boltzmann-Uehling-Uhlenbeck (GiBUU) model to questions relevant to current and future long-baseline neutrino experiments, and we address in particular the relevance of charged-current reactions for neutrino-disappearance experiments. A correct identification of charged-current quasielastic (CCQE) events--which is the signal channel in oscillation experiments--is relevant for neutrino energy reconstruction and thus for the oscillation result. We show that about 20% of the quasielastic cross section is misidentified in present-day experiments and has to be corrected for by means of event generators. Furthermore, we show that a significant part of 1pi{sup +} (> 40%) events is misidentified as CCQE events, mainly caused by pion absorption in the nucleus. We also discuss the dependence of both of these numbers on experimental detection thresholds. We further investigate the influence of final-state interactions on the neutrino energy reconstruction.