Reading a TString TBranch from a TTree

ROOT
2

In principle, this should be the right way:

TString *paddle = nullptr;
TString *beam_blocker = nullptr;
TTree *t = (TTree*)f_root->Get("DICER");
if (t) {
   t->SetBranchAddress("paddle"      , &paddle);
   t->SetBranchAddress("beam_blocker", &beam_blocker);
}

[edited to add the required pointer initialization]