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Exotic Cascades at NA49

Kre šo Kadija Ruđer Bošković Institute, Zagreb,Croatia. Exotic Cascades at NA49. Outline. NA49 experimental results Exotics - status Current efforts T o do list. 1. NA49 Experiment. VTPC-1 (VTPC-2+MTPC). dp/p 2 = 7 x (0.3) 10 -4 (GeV/c) -1. dE/dx resolution: 3-6 %.

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Exotic Cascades at NA49

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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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