Krešo Kadija Ruđer Bošković Institute, Zagreb,Croatia Exotic Cascades at NA49 Krešo Kadija Ruđer Bošković Institute, Zagreb,Croatia

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

NA49 Experiment VTPC-1 (VTPC-2+MTPC) dE/dx resolution: 3-6 % dp/p2 = 7 x (0.3) 10-4 (GeV/c)-1 dE/dx resolution: 3-6 % (sTrig= 28.1 mb)

Data Sample p+p at = 17.2 GeV Before vertex cut After Vertex Cut 1999 1.2 M 0.66 M 2000 2.7 M 1.5 M 2002 2.9 M 1.6 M Total 6.8 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

X5 search X- selection: L 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 z x y X - bx by MV

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

Primary pion selection |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 p

Additional cuts cos(q) < 0.997 (q > 4.5) X- X+ Background Signal q: angle between X i p p- X- q 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

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

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

Systematics study I Remove resonances: events with p- K- p p+ 497.6 ±10 769.0 ±60 892.0 ±30 1115.7 ±10 K+ 1019.0 ±10 1520.0 ±15 By changing: - mass cuts around X and L - dE/dx cut - number of points cut - bx, by cuts - e.t.c. Peak remains robust !

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

Systematic study III – mass cut L X-

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

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

Current efforts Levenberg-Marquardt fitting procedure 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 Use a consistent (debuged) code for all data ! New V0 and X finder ! 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)

Verify X- - and check non-exotic X* 1 |M(pp)-M(L)| < 0.015 GeV |M(Lp)-M(X)| < 0.015 GeV |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]

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

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

Existence of J=3/2 Q partner….??

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

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

M(pKS ) : Preliminary results 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

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

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  LK etc. Look for other pentaquark states p L X W X- - K NA49 preliminary pp data Microcanonical statistical model F. M. Liu, H.Stoecker, K. Werner , hep-ph/0404156

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