Towards exploring $U_{e3}$

Abstract

It is emphasized that resolution of the ${\theta }_{23}$ ambiguity is important for determination of ${\theta }_{13}$ if ${\sin }^{2}2{\theta }_{23}<1$, and resolution of the sgn($\Delta m_{31}^2$) ambiguity is important for determination of the CP phase $\delta$. I discuss the prospects of resolution of the ${\theta }_{23}$ ambiguity etc. in the future long baseline experiment after the JPARC experiment measures the oscillation probabilities $P({\nu }_{\mu }\to {\nu }_e)$ and $P({\bar{\nu }}_{\mu }\to {\bar{\nu }}_e)$ at $|\Delta m_{31}^2|L/4E=\pi /2$.

Comments: 8 pages, 5 sets figures, uses ws-procs9x6.cls. Invited talk at 5th Workshop on Neutrino Oscillations and their Origin (NOON2004), Odaiba, Tokyo, Japan, 11-15 Feb 2004