Second moment of degree three $L$-functions

Abstract: Let $F$ be a Hecke-Maass cusp form for $SL(3,\mathbb{Z})$. We obtain a non-trivial upper bound of the second moment of $L(F,s)$ in $t$-aspect: $$ \int_{T}^{2T}|L(F,1/2+it)|^2 dt\ll_{F,\epsilon} T^{3/2-3/88+\epsilon}.$$