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Exotic Cascades at NA49: Current Status and Future Efforts in Experimental Results Analysis

Explore the NA49 experimental results on exotic particles and cascades, focusing on data samples, vertex cuts, primary pion selection, systematics studies, Levenberg-Marquardt fitting procedure, and more. Current efforts involve improving data analysis and resolution, detector alignment, and excluding certain tracks. Future plans include expanding data samples, verifying old results, investigating known resonances, and searching for other decay channels and pentaquark states.

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Exotic Cascades at NA49: Current Status and Future Efforts in Experimental Results Analysis

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  1. KrešoKadija Ruđer Bošković Institute, Zagreb,Croatia Exotic Cascades at NA49

  2. Outline • NA49 experimental results • Exotics - status • Current efforts • To do list 1

  3. NA49Experiment VTPC-1 (VTPC-2+MTPC) dp/p2 = 7 x (0.3) 10-4 (GeV/c)-1 dE/dx resolution:3-6 % (sTrig= 28.1 mb)

  4. Data Sample p+p at = 17.2 GeV Before vertex cut After Vertex Cut 19991.2 M 0.66 M 2000 2.7 M 1.5 M 2002 2.9M 1.6 M Total6.8 M 3.76 M Main vertex cuts: 1.) fit converged 2.) x2+y2< 1 cm2 3.) -590.5 cm < z < -572.5 cm i.e. within target

  5. X - y x z MV by bx X5search X-selection: Distance to Bethe- Bloch curve: |dbb| < 3 s |M(pp-) - M(L)| < 0.015 GeV Z X- Zmain_vtx > 12 cm X- position at main vertex (bx , by): |bx| < 2 cm |by| < 1 cm p(from X- decay) position at main vertex |by|> 0.5 cm L

  6. V0 and X Invariant Mass Spectra X-peak 1640 events L peak |M(Lp)-M(X)| < 0.015GeV X+peak L peak 551 events

  7. Primary pion selection (- , + p) p • |dbb| < 1.5 s, dbb .... distance to Bethe-Bloch curve • position at main vertex (bx , by): |bx| < 1.0 cm |by| < 0.5 cm • # of points > 10

  8. X- q p- X-X+ p--1.5 s < dbb < 1.5s -1.5 s < dbb < 1.5 s p+-0.5 s< dbb < 1.5s -1.5 s < dbb < 1.5 s p > 3 GeV/c p > 3 GeV/c Additional cuts cos(q) < 0.997(q > 4.5) Background Signal q: angle betweenX i p

  9. Final Xp Invariant Mass Distributions Baryon spectra: peak at 1.86 GeV Antibaryon spectra: enhancement at the same mass C. Alt et al., Phys. Rev. Lett. 92

  10. Summed spectra M = 1.862 ± 0.002 GeV/c2 G≤ 18 MeV/c2

  11. Systematics study I Remove resonances: events with By changing: - mass cuts around Xand L - dE/dx cut - number of points cut - bx, by cuts - e.t.c. Peak remains robust !

  12. X-p (VENUS + GEANT + REC.) p: all negative particles p : true negative pions Systematics study II DATA ( X shoulders) No structure at 1.86 GeV

  13. Systematic study III – mass cut X- L

  14. pp (Q,X)X s = 1.9 TeV s = 1.9 TeV s =310 GeV e-e+ (Q,X)X e+e- (Q,X)X / / / / / / e p (Q,X)X pA (Q,X)X Bad news: Non observation of X5 Experiment Qs+ X5 Qc+ Energy Reaction CDF E690 pp (Q,X)X s= 39 GeV BaBar s =10.6 GeV ZEUS ALEPH s =91.2 GeV WA89 S- A XX ES =340 GeV HERA-B Ep=920 GeV Ee=300 GeV eBeO (Q,X)X FOCUS Ee=27.6GeV ed (Q,X)X HERMES

  15. If: s (X1530) s (X1860) s (X1860) ZEUS NA49 ZEUS vs. NA49 :Summed spectra NA49 s (X1530)

  16. Current efforts • Use a consistent (debuged) code for all data ! • New V0 and X finder ! • Use a consistent (debuged) code for all data ! • New V0 and X finder ! • Improved main vertex determination ! • Exclude V0 and X tracks from fit • Use higher quality tracks • Further improvement of experimental resolution • Residual corrections • Improve detector alignment (VT1,VT2,MTPC) • And with a new procedure (and 30% more data) …….. Levenberg-Marquardt fitting procedure 9 parameter fit(V0) 4 parameter fit 13 parameter fit(X)

  17. Verify X- - and check non-exotic X* 1 |M(pp)-M(L)| < 0.015GeV |M(Lp)-M(X)| < 0.015GeV |dbbp,p| < 3 s 1+ 2 |bx|X< 2 cm |by|X< 1 cm |by|p >0.5 cm 1 X per event 1+2+ 3 |bx|p < 1 cm |by|p < 0.5 cm |dbbp| < 1.5 s # of points > 10 1+2+3+ |dbbp| < 1 s ptotp > 3 GeV M(X- p+)[GeV/c2]

  18. In SU(3) 10 10 8 Check existence of 8f Q+ + X3/2 X3/2 - - X3/2 X1/2   X(1530)0 p+ X(1530)0 p- X(1530)0 p-

  19. X(1530)0 p: PRELIMINARY No evidence for X+3/2to X(1530)0 p+ decay X(1530)0 p+ No cuts ? X(1530)0 p- No evidence for X+3/2to X(1530)0 p+ decay X(1530)0 p+ pp > 3 GeV/c + - 0.5 s < dbb < 1.5 s p X(1530)0 p- ?

  20. Existence of J=3/2 Q partner….??

  21. Check existence of J=3/2 X partner…. 1780 ?! 1860

  22. pp (Q,X)X s = 1.9 TeV s =310 GeV s = 1.9 TeV e-e+ (Q,X)X e+e- (Q,X)X / / / / / / / e p (Q,X)X pA (Q,X)X NA-49 s =17.6 GeV pp (Q,X)X X5and Q : members of a multiplet Experiment Qs+ X5 Qc+ Energy Reaction CDF E690 pp (Q,X)X s= 39 GeV BaBar s =10.6 GeV ZEUS ALEPH s =91.2 GeV WA89 S- A XX ES =340 GeV HERA-B Ep=920 GeV Ee=300 GeV eBeO (Q,X)X FOCUS Ee=27.6GeV ed (Q,X)X HERMES

  23. 0 M(pKS ) : Preliminary results M(pKS0) selected KS0 selected p and KS0 M(pKS0) Additional proton selection • 0.5 s < dbb < - 3 s • |bx| < 1 cm, |by| < 0.5 cm • 5 GeV/c < pp < 30 GeV • 0.2 GeV/c < pT < 0.9 GeV/c MQ+= 1.526±0.002 GeV/c2, G < 15 MeV/c2

  24. Additional proton selection • 0.5 s < dbb < - 3 s • |bx| < 1 cm, |by| < 0.5 cm • 5 GeV/c < pp < 30 GeV • 0.2 GeV/c < pT < 0.9 GeV/c 0 M(pKS ) : Preliminary results + 80 < # of points (primary proton) < 145 ????

  25. p p K L X W X- - NA49 preliminary pp data Microcanonical statistical model F. M. Liu, H.Stoecker, K. Werner , hep-ph/0404156 To do list:Summary • Data sample increase by up to ~ 30% • Improve analysis, reanalyse data and: • Verify old results • Look for known resonances • Look for other possible decay channels X5 X(1530) p, X5 LKetc. • Look for other pentaquark states

  26. T. Antičić K. Kadija T. Šuša Ruđer Bošković Institute, Zagreb,Croatia The NA49 Collaboration 1

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