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Resonances in

Resonances in. March 7, 2018 | Albrecht Gillitzer. PANDA Collaboration Meeting 1/18, GSI Darmstadt. Status of Resonances. Little known Decay modes :. ?. ?. Studied Event Samples. beam momentum p = 4.6 GeV /c data set (1): 4 M events (PHSP)

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Resonances in

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  1. Resonances in March 7, 2018 | Albrecht Gillitzer PANDA Collaboration Meeting 1/18, GSI Darmstadt

  2. Status ofResonances • Little known • Decaymodes: ? ?

  3. Studied Event Samples • beam momentum p = 4.6 GeV/c • dataset (1): 4 M events (PHSP) • dataset (2): 5 M events & c.c. with & c.c. & cont., weight 1/7 each sub-channel • dataset (3): 22 M events DPM • dataset(4): 6.6 M events (PHSP)

  4. Simulation & Analysis Parameters • same procedurefor all datasets • standarddetector, Geant4, ‚recoideal‘, ideal PID • PandaRoottrunk 30122 & 30127 • novisibledifference bothdatasetsadded • defineasstableparticles in EvtGendecayfile • usemodifieddecayof in Geant4  98.6% signalevents • both MC & recoinfo in onentuple (quasi-complete)

  5. Analysis Procedure • require all particles in thesignaldecaytree in the MC list • require all final particlecandidatespresentwith ‚hit tag‘ forchargedparticles: >3 hits in anycentraltrackingdetector • reconstruct vertices (1.: vtx fit, 2.: massconstraint fit) • reconstruct • reconstructvertices (1.: vtx fit, 2.: massconstraint fit) • reconstructsystem (vtx fit) • reconstructsystemsystem (4C fit) • controlspectraforeachstep

  6. MC Signal Efficiencies Data Set (1) • MC losses due to: • interaction • missinghitsofdaughterparticles

  7. Resonstruction Efficiency StableParticles • n-tupleonlyfilledforfully ‚reconstructable‘ events • separate analysis

  8. ReconstructionEfficiencies reference: reconstructableevents 1: reco 0.916 2: reco true 0.838 4: reco 0.924 5: reco true 0.845 8: reco 0.743 9: reco true 0.708 11: reco 0.748 12: reco true 0.713 15: reco 0.728 16: reco true 0.355 17: recoconv. 0.076 true + conv. 0.431 20: reco 0.522 23: cand true 0.180 25: reco 0.136

  9. MC TruthFraction Final Sample 4C fit & masscut reference: final sample 1: true 0.996 3: true 0.996 6: true 0.996 8: true 0.995 11: true 0.805 12: conv. 0.144 true + conv. 0.949 23: true* 0.798 * conv. not included.incl. conv.: 0.941

  10. Histograms • ~1000 histogramscreated here: onlyfew final plots ! • MC spectra: • Px, Py, Pz, P, Pt, θ, PtvsPz, θvs P for all particles: • decaypositionsof • 2-body massspectra & Dalitzplot • 4 analysislevels: ‚generated‘, ‚reco‘, ‚XiXi‘, ‚final‘ • recospectra: • vertex: position, reco-true, pulls • all fits (vtx, m.c.f., 4C; ): : and prob. • massspectraofcompositeparticles at different stages • 4-momenta of all particlesbefore & after 4C fit • large numberofcontrolspectra

  11. MC generated MC ‚reco‘ MC ‚XiXi‘ MC ‚final‘

  12. MC ‚final‘ Reconstructed ‚final‘

  13. Signal Data Set (2): IncludeΞ*Resonances • decay ofthesystemto (b = 1/7 each): • 5 M events • all recoefficiencyvaluesare same asfordataset (1)

  14. MC generated MC ‚reco‘ MC ‚final‘ Reconstructed ‚final‘

  15. MC generated MC generated Reconstructed ‚final‘ Reconstructed ‚final‘

  16. Data Set (3): DPM Background • identical analysisprocedure • 2 events out of 22 millionsurvived all selectioncriteria • botheventshave prompt decay vertices within 3 mm • requiring and both events are eliminated • signal-to-background: (90% C.L.) • significance: (90% C.L.)

  17. Data Set (4): • 6.6 M events, (extrapolatedfromdata at higher) • 674 eventssurvived all selectioncriteria • mosteventshave decay vertices within few mm • after requiring and , 34 events survive • signal-to-background: • significance:

  18. beforevertexcut after vertexcut

  19. Release Note Ready

  20. Summary • comprehensive analysisof4.6 GeV/c includingbackgroundstudies • over-all reconstructionefficiency: ~3.5 % • reconstructionsignificantlycontributestoefficiencylosses (~43%) andto ‚fake‘ combinations in the final data sample (~5%) • acceptanceandreconstruction uniform acrossphasespace • 22 M DPM backgroundevents S/B > 4.6 • 6.6 M events S/B = 47 • releasenotereadyfordistributiontothecollaboration

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