Neutrino oscillation from the beam with Gaussian-like energy distribution

TL;DR

This paper models neutrino oscillations using Gaussian-like energy distributions, revealing wave packet expansion effects that impact the measurement of mixing angles and oscillation properties in long baseline experiments.

Contribution

It introduces a Gaussian-like wave packet approach to simulate neutrino energy distribution and studies its effects on oscillation behavior and parameter measurement.

Findings

Wave packet expansion during propagation affects oscillation amplitude.

Larger Gaussian packet width reduces oscillation amplitude.

Oscillation period increases with packet width.

Abstract

A recent neutrino experiment at Daya Bay gives superior data of the distribution of the prompt energy. In this paper, the energy distribution presented in the experiment is simulated by applying a Gaussian-like packet to the neutrino wave function received by the detector. We find that the wave packet of neutrinos is expanded during the propagation. As a result, the mixing angle $\theta_{13}$ is more difficult to be measured than $\theta_{12}$ and $\theta_{23}$ in long baseline experiments. Some other propagation properties, such as the time evaluation of the survival probability, the neutrino oscillation and the $CP$ violation, are also studied with the employment of the coherent state method. When the Gaussian packet width increases, the amplitude of the neutrino oscillation decreases, whereas the oscillation period increases gradually.