The symmetric-square L-function on the critical line

We prove an asymptotic formula for the first moment of the symmetric-square L  -functions L(sym2f,s) on the critical line for cusp forms f of weight k, level N and real primitive character χ modulo N  , as N→∞N→∞. It follows that for any t∈Rt∈R, there exists f   such that L(sym2f,1/2+it)≠0.