Opened 6 years ago
#1374 new How to
invariant mass of high-pT hadronic-tau leptons
| Reported by: | Ernesto Arganda | Owned by: | |
|---|---|---|---|
| Priority: | major | Milestone: | |
| Component: | Delphes code | Version: | Delphes 3 |
| Keywords: | hadronic tau, invariant mass | Cc: | szynkman@…, nicolas.mileo@…, xabier.marcano@…, robamorales@…, ernesto.arganda@… |
Description
Dear Delphes Team,
we have generated 10k events of the Drell-Yan (DY) production of a tau-lepton pair, by means of the interface MadGraph+Pythia8+Delphes3, for a LHC center-of-mass energy of 14 TeV, setting the default cards in each case. We have also generated 10k events for the production of a heavy neutral MSSM Higgs boson with a mass of 1 TeV, decaying also into a tau-lepton pair, and using the same default cards. The distribution of the hadronic-tau invariant mass is the expectable for the DY events (see Figure 2 of the PDF we have attached with a simple analysis performed with MadAnalysis 5), but we do not understand the distribution of the hadronic-tau invariant mass obtained for the heavy MSSM Higgs boson, since the range of this variable goes from 0 GeV to very large mass values, up to 100 GeV or even larger (see also Figure 2), very different to the DY result, that peaks around 2 GeV and falls up to 20 GeV, with no events for larger mass values (see Figure 3, in which we have performed a zoom of the invariant mass distribution for the range [0 GeV, 20 GeV]).
On the other hand, the distribution of the transverse momentum (pT) of the tau leptons coming from the Higgs decay is also very different with respect to the DY process (see Figure 1). In order to figure out if the differences on the invariant mass distributions could be related to the different pT, we have imposed at the generator level (MadGraph run card) a cut on the tau-lepton transverse momentum (pT(tau) > 250 GeV) and generated again 10k DY and MSSM Higgs events. As you can see in Figures 2 and 3, the invariant mass distribution does not change at all for the MSSM Higgs events, since the Higgs boson we have produced is very heavy and the tau-leptons coming from its decay are very energetic, with very high pT, as expected. However, the invariant mass distribution for the DY tau leptons produced with the pT cut changes drastically, resulting in a very similar profile to the tau leptons coming from the Higgs decay (with or without pT cut).
Do you know why we are obtaining so large hadronic-tau invariant mass values for high-pT tau leptons? What are the reconstruction method for the hadronic-tau leptons? Thank you very much for your help.
Best regards,
Ernesto Arganda, Nicolás Mileo and Alejandro Szynkman.
