Tau polarization in quasielastic charged-current neutrino(antineutrino)–nucleus scattering

Abstract

The quasielastic charged-current (CC) tau neutrino (antineutrino)-nucleus scattering is considered. The dependence of tau polarization on nuclear-structure effects is discussed in detail. The description of the nucleus is based on the Mean-Field Theory (MFT). The ground state of nucleus is described using the Relativistic Fermi Gas model (FG). The effective mass is introduced as well as the ring Random Phase Approximation (RPA) effects are taken into account in the framework of relativistic meson-nucleon model. The Local Density Approximation (LDA) is used for the argon nucleus, having in mind possible application to the ICARUS experiment. The discussion concentrates on the threshold region where the τ − can be unpolarized and the nuclear effects play an important role.

Progress and open questions in the physics of neutrino cross sections at intermediate energies

“…, -nucleus scattering [127]. The impact of RPA correlations at MiniBooNE energies ∼ ν E 750 MeV is quite significant.…”

Nuclear effects on lepton polarization in charged-current quasielastic neutrino scattering

“…This model basically consists on a relativistic local Fermi gas (LFG) including nuclear dynamical corrections such as some kind of relativistic RPA correlations and an effective mass for the nucleons inside the nucleus (this is an approximate way of taking into account the FSI). However the model of [33], first presented in [34,35], has not been tested in other nuclear reactions such as (e, e ′ ). In Sect.…”

“…We account for relevant reaction mechanisms where two nucleons participate, by dressing the nucleon propagators in the nuclear medium. In particular these effects change the dispersion relation of the nucleon, which in some works is taken into account by the over-simplified method of introducing an effective mass for the nucleon [33].…”

Polarization of τ in quasielastic (anti)neutrino scattering: The role of spectral functions

“…We will focus on the quasi-elastic (QE) region in which the single nucleon knock-out is the dominant reaction mechanism. Previous works on ν τ andν τ scattering have considered the nucleus as an ensemble of free nucleons [4], or used the Random Phase Approximation (RPA), and an effective nucleon mass to describe the initial nuclear state [5]. The use of an effective mass for the nucleon is a simplified method to account for the effects due to the change of its dispersion relation inside of a nuclear medium.…”

“…In addition, one should bear in mind that RPA corrections take into account the absorption of the gauge boson, mediator of the interaction, by the nucleus as a whole instead of by an individual nucleon, and their importance decreases as the gauge boson wave-length becomes much shorter than the nuclear size. Thus, RPA effects on the polarization observables become little relevant, even for the total or partially integrated cross sections [6,25], for a great part of the phase-space accessible in the CC reaction [5,7]. This work is organized as follows.…”