Nuclear effects in neutrino-nucleus interactions: the role of spectral functions
- Autores: Joanna Ewa Sobczyk
- Directores de la Tesis: Juan Miguel Nieves Pamplona (dir. tes.)
- Lectura: En la Universitat de València ( España ) en 2019
- Idioma: español
- Tribunal Calificador de la Tesis: Angels Ramos Gómez (presid.), Luis Álvarez Ruso (secret.), Maria Benedetta Barbaro (voc.)
- Programa de doctorado: Programa de Doctorado en Física por la Universitat de València (Estudi General)
- Materias:
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- Resumen
In this Thesis we present a wide analysis of nuclear effects which are crucial for a proper description of neutrino-nucleus scattering. We use a well-established many-body framework, successful in modelling a great variety of nuclear processes. In particular, we analyze the role of the spectral functions (SF) accounting for the modifications of the dispersion relation of nucleons embedded in the nuclear medium. We concentrate on processes mostly governed by one-body mechanisms, studying possible approximations to evaluate the particle-hole propagator using spectral functions and performing a series of analyses and comparisons with other approaches for the quasielastic mechanism.
We also investigate how to include together SFs and long-range random-phase approximation (RPA) correlations in the evaluation of nuclear responses, discussing the interplay between both types of nuclear effects. At low energy transfers (< 50 MeV), we compare our predictions for inclusive muon and radiative pion captures in nuclei, and charge-current (CC) neutrino-nucleus cross sections with experimental results. We also present an analysis of intermediate energy quasielastic neutrino scattering for various targets and (anti)neutrino CC processes. Moreover, we briefly compare our SF and RPA results to predictions obtained within other approaches. We perform a comparison of our SF model (and other approaches) with the electron scattering inclusive data on 12C, in the energy region relevant for the T2K experiment.
Further, we pay attention to scaling properties of our model. Scaling features of the nuclear electromagnetic response functions unveil aspects of nuclear dynamics that are crucial for interpreting neutrino- and electron-scattering data. Obtained scaling functions are characterized by an asymmetric shape, although less pronounced than that obtained from experiment. As we will show, this asymmetry, only mildly affected by final state interactions, is mostly due to nucleon-nucleon correlations, encoded in the continuum component of the hole SF.
Next we present results for the quasielastic weak production of Lambda and Sigma hyperons induced by antineutrinos scattering off nuclei. We employ hole SFs and we describe the propagation of the hyperons in the nuclear medium by means of a Monte Carlo cascade. The latter strongly modifies the kinematics and the relative production rates of the hyperons, leading to a non-vanishing Sigma+ cross section, to a sizable enhancement of the Lambda production and to a drastic reduction of the Sigma0 and Sigma- distributions. We also compute the quasielastic weak Lambda c production cross section, paying special attention to estimate the uncertainties induced by the model dependence of the vacuum n -> Lambda c weak matrix element.
Lastly, we study the tau polarization in CC quasielastic (anti)neutrino-nucleus scattering. We show that the SFs, while playing an important role in the prediction of the differential cross sections, produce much less visible effects on the polarization components of the outgoing tau.
