RooAddPdf sum("sum","backgroudns and signal pdfs",RooArgList(bipdf,tlpdf,b81pdf,b82pdf,b83pdf,b84pdf,b85pdf,b86pdf),RooArgList(nbi,ntl,nb81,nb82,nb83,nb84,nb85,nb86));

double b1=5.0;
double b2=12.0;

 RooGaussian fconstraint2("fconst2","fconst2",ntl,RooConst(b2),RooConst(b2*0.40));
  RooGaussian fconstraint("fconst","fconst",nbi,RooConst(b1),RooConst(b1*0.50));
 // RooGaussian fconstraint("fconst","fconst",nbi,RooConst(intb),RooConst(intb*0.10));

  RooArgSet combined(fconstraint2,fconstraint);
   
 RooDataHist  data("data","dataset with t",RooArgList(x),Import(*newdata2));

  RooNLLVar nll("nll","nll",sum,data,Extended(kTRUE));

   RooMinuit m(nll);
  m.migrad();
  m.hesse(); 
  //-------------------------------------------------------------------//

 
   
   RooFitResult* r2=sum.fitTo(data,ExternalConstraints(combined),Save());