Semi-inclusive neutrino-nucleus reactions at intermediate energies

Abstract

The discovery of neutrino oscillations in 1998 by the Super-Kamiokande experiment opened a new frontier in particle physics. Past, ongoing, and forthcoming experiments are dedicated to unraveling the mechanisms responsible for neutrino oscillations by measuring the physical parameters governing this phenomenon. As for now, the neutrino mass hierarchy remains unknown, yet it is an important physical information. Additionally, neutrino oscillations have hinted at the existence of charge-parity violation within the lepton sector. To determine the presence of such violation, a fundamental parameter of the PMNS paradigm needs to be measured. Presently, accelerator-based neutrino experiments are actively gathering data, while new experiments are in development, all geared towards quantifying the degree of CP violation present in neutrino oscillations. One of the main limiting systematic errors in neutrino oscillation physics comes from our limited knowledge of neutrino-nucleus interactions. To help to constrain nuclear effects for the modeling of neutrino-nucleus interactions and improve the reconstruction of the neutrino energy for oscillation experiments, in this thesis we have studied semi-inclusive neutrino interactions with complex nuclei at intermediate lepton energies, i.e., neutrino beam energies ranging from 0.5 up to 10 GeV. Due to the kinematics of the particles involved and the complexity of the interaction, we have developed a fully relativistic and quantum mechanical model able to describe not only inclusive but also semi-inclusive electron and neutrino reactions with complex nuclei. Starting with Chapter 1, an introduction to neutrino oscillations, acceleratorbased neutrino experiments and neutrino-nucleus interactions is presented. Chapter 2 is mainly focused in the general definition of a semi-inclusive neutrinonucleus reaction and the analysis, from a theoretical point of view, of semiinclusive results using different models of the nucleus, but neglecting the effects introduced by final state interactions. Chapter 3 is entirely dedicated to the description of the one-proton knockout process, a type of semi-inclusive reaction, using a fully relativistic and quantum mechanical model of the nuclear dynamics and final-state interactions called relativistic distorted-wave impulse approximation. In Chapter 4 we review the current approach used by neutrino event generators to describe semi-inclusive reactions. Different approximations for the description of semi-inclusive reactions are compared with semi-inclusive cross section measurements performed by different international collaborations, like T2K, MINERvA and MicroBooNE, in Chapter 5. Finally, in Chapter 6 a summary and the conclusions of this thesis are presented.