section the general criterion in the parameter space for the localized graviton on the 3-brane to be massless. We will also show that the massless graviton at $\xi = 0$ is followed via a coupling constant renormalization. In section 4 we will consider the free particle case with an $1d$-box constraint and $\delta$-function potentials at the both boundaries as a toy model of RS1. The final expression is dependent on the two free parameters $\xi_1$ and $\xi_2$ which parametrize the BCs arising at both boundaries of $1d$ box. In section 5 we will compute the fixed-energy amplitude for RS1 which depends on two free parameters $\xi_1$ and $\xi_2$. We will show in this section that there is no localized massless graviton on both branes. For positive-tension brane, however, the massless graviton can appear when the width of $1d$ box is infinity, which is essentially identical to RS2. For the negative-tension brane our numerical calculation indicates there is no localized massless graviton regardless of the size of $1d$ box. In final section a brief conclusion is given.

Toy Model 1: Free Particle on a half-line with $\delta$-function Potential
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In this section as a toy model of RS2 we will examine 