[Rivet] transverse sphericity in rivet

[Tobias Hülsing]

Hello!

I am trying to implement an ATLAS analysis in rivet.
We measured the transverse sphericity and I think your projection and 
our definition aren't the same.
In how far is it possible to implement "our sphericity" to rivet?
Below is our routine to calculate the sphericity.

Best regards,

Tobias

/double
CalcTranSphericity(double sumpx2, double sumpy2, double sumpxpy) //sum 
of px^2, py^2, px*py. Input: Momenta of all charged particles within 
|eta|<2.5, pT>500MeV
{
   double marray[4];
   for (int i = 0; i < 4; i++)
     {
       marray[i] = 0;
     }
   marray[0] = sumpx2;
   marray[1] = sumpxpy;
   marray[2] = sumpxpy;
   marray[3] = sumpy2;

   // use root matrix to find eigenvalues...
   TMatrixDSym matrix(2);
   matrix.SetMatrixArray(marray);

   TMatrixDSymEigen eigen(matrix);
   TVectorD E = eigen.GetEigenValues();

   double lambda1 = 0;
   double lambda2 = 0;

   if (E[0] < E[1])
     {
       lambda1 = E[0];
       lambda2 = E[1];
     }
   else
     {
       lambda1 = E[1];
       lambda2 = E[0];
     }

   double ST = 0;
   ST = 2 * lambda1 / (lambda1 + lambda2);
   //  std::cout<<"Check:lambda1+lambda2 "<<lambda1 + lambda2 <<std::endl;
   if ((lambda1 + lambda2) == 0) return -1;
   return ST;
}/
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