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Hypertriton 3 body decay channel invariant mass in Pb-Pb collisions at sqrt(s_NN)= 2.76 TeV (2011 data taking)

Figure Information
Scope: PWG
PWG-LF (Light Flavour Spectra)
Energy
2.76 TeV
System
Pb-Pb
Figure Group
Hypertriton and anti-hypertriton production
Figure Image
Figure image (.eps)
2017-Jul-05-InvariantMass_hyp3body_2011PbPb_Performance.eps
Figure image (.pdf)
2017-Jul-05-InvariantMass_hyp3body_2011PbPb_Performance.pdf
Figure Caption

Hypertriton invariant mass spectrum obtained from the reconstruction of its 3 body decay channel. The number of events selected is 19x10^6 (0-10%) in Pb-Pb collisions at 2.76 TeV (2011 data taking)

Detail description

hypertriton candidates are reconstructed in the mesonic weak charged 3 body decay channel deuteron + proton + pion^{-}.

Analysis performed on LHC11h_2 using ESDs

Event selection:

  • Trigger: kCentral, kSemiCentral
  • Centrality: 0-10%, 10-50%
  • z primary vertex: -10 < z_pv < 10 cm

Track cuts:

  • TPCrefit: kTRUE
  • Reject kink daughters
  • Number of TPC clusters > 80
  • chi2/clusters < 5
  • pseudorapidity |eta| < 0.9

Special additional cuts for pion candidates:

  • Number of TPC clusters > 100
  • 0.2 <pT < 1.2 GeV/c

Decay products are identified with the TPC (3\sigma inclusion) and further cuts are applied to select good tripler candidates (e.g. DCA between tracks, angle between tracks)

Additional selection on decay topology is applied:

  • cosine of pointing angle > 0.999
  • ct > 1 cm
  • candidate hypertriton pT range: 2 - 10 GeV/c
  • normalized decay lenght > 3
  • rapidity |y| < 0.5