Constraints on $|U_{e3}{|}^2$ from a Three-Neutrino Oscillation Analysis of the CHOOZ Data

Abstract

Results of a new analysis of the CHOOZ data, performed in the framework of three-neutrino mixing, are presented. Both the cases of normal and inverted neutrino mass hierarchy are considered. The parameters characterizing the solar neutrino oscillations, $\Delta m_{\odot }^2$ and ${\theta }_{\odot }$, are assumed to lie in the region of the large mixing angle (LMA) MSW solution of the solar neutrino problem. For $\Delta m_{\odot }^2$ not exceeding $10^{-4}e{V}^2$ the new CHOOZ exclusion curve in the $\Delta m_{31}^2-|U_{e3}{|}^2$ plane practically coincides with the exclusion curve obtained in the two-neutrino mixing case. For $\Delta m_{\odot }^2$ bigger than or equal to $2x10^{-4}e{V}^2$, the constraints of the CHOOZ data on $|U_{e3}{|}^2$ are more stringent than those obtained in the two- neutrino oscillation analysis.

Comments: 13 pages, LATEX; 10 pages of text, 3 eps-files; the text includes 1 table and 3 figures