Find the mass with TLorentzVector::SetPtEtaPhiE

Hi all,
I have a problem with TLorentzVector::SetPtEtaPhiE, if I write:

tag_jet1.SetPtEtaPhiE(Pt,Eta,Phi,E); tag_jet2.SetPtEtaPhiE(Pt,Eta,Phi,E); dijet = tag_jet1 + tag_jet2; mass = dijet.M();

I obtain negative mass.
where is my mistake, do you have any idea?
Thank you
Ciccio

Hi,

you get negative masses when E^2 < P^2. So you are setting value of E in SetPtEtaPhiE which are too small compared to P

Best Regards

Lorenzo

Hi,

thank you I found my mistake.
Ciccio