LHC signature with long-lived stau in high reheating temperature scenario

We study the possibility of observing the stau signal at LHC in case that the gravitino is the lightest supersymmetric particle and the stau is the next lightest supersymmetric particle in high reheating temperature scenario. We show that a number of stau signals can be observed at LHC for $\sqrt{s}=7 {\rm TeV}$ and an integrated luminosity of $1 {\rm fb}^{-1}$ in most of the parameter region for the reheating temperature $T_R\gsim{\cal O}(10^8) {\rm GeV}$. We also show that the parameter region with $T_R\gsim2\times10^9 {\rm GeV}$, which is consistent with the thermal leptogenesis, is all covered for $\sqrt{s}=14 {\rm TeV}$ with $10 {\rm fb}^{-1}$.