Defining non numerical cut range

Hi,
I need to determine the threshold value for 0.5PE in dark count analysis. For this, I first determined the gain of the measurement, and then using the TCut command, I determined the height of SIngle PE. Since I dont want to edit my code for each analysis, I used following code. But it doesnt works. It says that I cant use non numerical cut range even though I have already defined that in terms of number.
Please correct my code where it is wrong.[code]

Double_t ADC = 30500.0;            //Conversion Factor to Charge

//----------------->>>>>>
TCanvas *c1= new TCanvas ("c1", "c1", 700, 600);
//TCut general = "RMS> 8 && RMS<12 && Area>1000 && Area< 2500";
TCut general = "RMS> 8 && RMS<12";
c1->SetLogy();

//==================================================================>>>>>>>>>>>>>>>>>>>>
   


    TH1F *h1= new TH1F ("h1", "Area", 400, 0, 10000);

     h1->GetXaxis()->SetTitle("Signal Electrons");
     h1->GetXaxis()->CenterTitle(1);
     h1->GetXaxis()->SetNdivisions(10);
     h1->GetXaxis()->SetTitleOffset(1.1);
     h1->GetXaxis()->SetTitleSize(0.045);
     h1->GetXaxis()->SetTitleFont(42);
     h1->GetXaxis()->SetLabelSize(0.045);
     h1->GetXaxis()->SetLabelOffset(0.01);
     h1->GetXaxis()->SetLabelFont(42);

h1->GetYaxis()->SetTitle("Count");
     h1->GetYaxis()->SetTitleSize(0.045);
    h1->GetYaxis()->SetTitleOffset(1.2);
    h1->GetYaxis()->SetTitleFont(42);
    h1->GetYaxis()->CenterTitle();
     h1->GetYaxis()->SetLabelFont(42);
     h1->GetYaxis()->SetLabelSize(0.045);
    h1->GetYaxis()->SetLabelOffset(0.01);
T1->Draw("Area>>h1",general);

TF1 *f= new TF1 ("f", "gaus", 0, 10e5);
h1->Fit ("f", "", "", 1100, 2200);
f->SetLineColor (kRed);
double gain = f->GetParameter(1);
Gain= gain*30500/100;
f->Draw("same");
double mean = f->GetParameter(1);
double sigma = f->GetParameter(2);

TLatex* text = new TLatex();
text->SetTextSize(0.06);
   text->DrawLatex(3000, 10e04, Form("Gain = %e",Gain));

TCanvas *c2= new TCanvas ("c2", "c2", 700, 600);
c2->SetLogy();
TCut cut= "Area> mean-sigma && Area< mean + sigma";

TH1F *h2= new TH1F ("h2", "", 400, 0, 10000);
T1->Draw("Height>>h2", cut);

}
[/code]

Try: TCut cut = TString::Format("abs(Area - %.17g) < %.17g", mean, sigma); or: TCut cut = TString::Format("TMath::Abs(Area - %.17g) < %.17g", mean, sigma); or: TCut cut = TString::Format("Area > %.17g && Area < %.17g", mean - sigma, mean + sigma);