is well fitted by $\Delta_c \sim w^{1/\phi}$ with $\phi^{-1} = 0.56(2)$ or $\phi =
1.78(6)$; see the inset of Fig. \[Fig:PCPphase\]. Let us assume the existence of the well-defined crossover scaling which is described by the scaling function [@DL9] $$\rho_p(\Delta,w;t) = t^{-\delta} {\cal F}(\Delta^{\nu_\|} t,
w^{\mu_\|} t),
\label{Eq:scaling}$$ where $\rho_p$ is the pair density and $\mu_\| = \nu_\|/\phi$ with $\phi$ estimated in the above. We examine whether the scaling function in Eq.  correctly describe the crossover near the PCP critical point.

![\[Fig:PCPphase\] (Color online) Phase boundary of the model of Eq.  at $q=0$ in $w-p$ plane. Symbols locate the numerically estimated critical points. The error of the critical point is smaller than the symbol size. The curve shows the least-square-fit result of the phase boundary. The absorbing (active) phase is above (below) the curve. Inset: the same but the vertical axis is $\Delta_c(w)$ in log-log scale. The slope corresponds to the inverse of the crossover exponent which is estimated as $\phi = 1.78(6)$. ](ParkFig3.eps){width="45.00000%"}

![\[Fig:mucollapse\] (Color online) Log-log plot of the scaling function Eq.  for the PCP crossover model using $\delta = 0.1595$ and $\mu = 0.97$. All curves are collapsed into a single curve. ](ParkFig4.eps){width="45.00000%"}

First, we measure the 