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Re: RhoError class in pandaroot [message #16767 is a reply to message #16766] Tue, 03 June 2014 11:57 Go to previous messageGo to previous message
Ralf Kliemt is currently offline  Ralf Kliemt
Messages: 507
Registered: May 2007
Location: GSI, Darmstadt
first-grade participant

From: *gsi.de
Hi Elisabetta,



The RhoCandidate stores the 4-momentum and its covariance matrix in the coordinates of (px, py, pz, e). The covariance is a "RhoError" type, which inherits from TMatrixD. The diagonal elements contain sigma^2 of the corresponding coordinate. If you want to get some error and pull distributions, you can do something like that:


for (j=0;j<muplus.GetLength();++j)
{
  TLorentzVector lv=muplus[j]->P4();
  RhoError lvCov=muplus[j]->P4Cov();
  hpullpx->Fill( ( lv.Px() - lvmc.Px() ) / sqrt( lvCov[0][0] ) );
  hpullpy->Fill( ( lv.Py() - lvmc.Py() ) / sqrt( lvCov[1][1] ) );
  hpullpz->Fill( ( lv.Pz() - lvmc.Pz() ) / sqrt( lvCov[2][2] ) );
  hpulle->Fill( ( lv.E() - lvmc.E() ) / sqrt( lvCov[3][3] ) );
}

If you need the other coordinates, you would have to convert that error matrix to those coordinates.

Cheers
Ralf
 
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