Transcript K. Kadija
Exotic Cascades at NA49 Krešo Kadija Ruđer Bošković Institute, Zagreb,Croatia [email protected] EPIPHANY, Cracow, January 6-8 2005. Outline NA49 experimental results Exotics - status Current efforts To do list [email protected] 1 EPIPHANY, Cracow, January 6-8 2005. NA49 Experiment dp/p2 = 7 x (0.3) 10-4 (GeV/c)-1 VTPC-1 (VTPC-2+MTPC) dE/dx resolution: 3-6 % (sTrig= 28.1 mb) [email protected] EPIPHANY, Cracow, January 6-8 2005. Data Sample p+p at s = 17.2 GeV Before vertex cut 1999 2000 2002 1.2 M 2.7 M 2.9 M Total 6.8 M After Vertex Cut 0.66 M 1.5 M 1.6 M 3.76 M Main vertex cuts: 1.) fit converged 2.) x2+y2< 1 cm2 3.) -590.5 cm < z < -572.5 cm [email protected] i.e. within target EPIPHANY, Cracow, January 6-8 2005. X5 search X- selection: Distance to Bethe- Bloch curve: |dbb| < 3 s L |M(pp-) - M(L)| < 0.015 GeV Z X- Zmain_vtx > 12 cm X - position at main vertex (bx , by): X y |bx| < 2 cm |by| < 1 cm p (from X - decay) position at main vertex - x by MV z |by| > 0.5 cm bx [email protected] EPIPHANY, Cracow, January 6-8 2005. V0 and X Invariant Mass Spectra X- peak 1640 events L peak |M(Lp)-M(X)| < 0.015 GeV X+ peak L peak [email protected] 551 events EPIPHANY, Cracow, January 6-8 2005. Primary pion selection (X- p, X+ p) |dbb| <p1.5 s, dbb .... distance to Bethe-Bloch curve position at main vertex (bx , by): |bx| < 1.0 cm |by| < 0.5 cm # of points > 10 [email protected] EPIPHANY, Cracow, January 6-8 2005. Additional cuts cos(q) < 0.997 (q > 4.5) Background Signal q: angle between X i p X- q p- X pp+ -1.5 s < dbb < 1.5s -0.5 s < dbb < 1.5s p > 3 GeV/c [email protected] -1.5 s < dbb < -1.5 s < dbb < p > 3 GeV/c EPIPHANY, Cracow, January 6-8 2005. 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 [email protected] EPIPHANY, Cracow, January 6-8 2005. Summed spectra M = 1.862 ± 0.002 GeV/c G [email protected] ≤ 18 MeV/c2 EPIPHANY, Cracow, January 6-8 2005. Systematics study I Remove resonances: pp+ 497.6 ±10 K+ p K- p 892.0 ±30 1115.7 ±10 892.0 ±30 1019.0 ±10 1520.0 ±15 1115.7 ±10 1520.0 ±15 events with 769.0 ±60 By changing: - mass cuts around X and L - dE/dx cut - number of points cut - bx, by cuts Peak remains robust ! - e.t.c. [email protected] EPIPHANY, Cracow, January 6-8 2005. Systematics study II X-p (VENUS + GEANT + REC.) p: all negative particles DATA ( X shoulders) p : true negative pions No structure at 1.86 GeV [email protected] EPIPHANY, Cracow, January 6-8 2005. Systematic study III – mass cut L [email protected] X- EPIPHANY, Cracow, January 6-8 2005. Bad news: Non observation of X5 Reaction Energy CDF pp (Q,X)X 1.9 TeV TeV / s == 1.9 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 Experiment Q s+ WA89 X5 Q c+ S- A XX ES =340 GeV HERA-B pA FOCUS eBeO (Q,X)X E e=300 GeV HERMES [email protected] (Q,X)X E p=920 GeV ed (Q,X)X E e=27.6GeV EPIPHANY, Cracow, January 6-8 2005. ZEUS vs. NA49 :Summed spectra NA49 If: s (X1530) s (X1860) [email protected] NA49 s (X1530) s (X1860) EPIPHANY, Cracow, January 6-8 2005. ZEUS Current efforts 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) [email protected] EPIPHANY, Cracow, January 6-8 2005. 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| |by| p p < 1 cm < 0.5 cm |dbbp| < 1.5 s # of points > 10 1+2+3+ |dbbp| < 1 s ptotp > 3 GeV M(X- p+)[GeV/c2] [email protected] EPIPHANY, Cracow, January 6-8 2005. Check existence of 8f Q+ In SU(3) 10 - X3/2 X3/2 X(1530)0 p- X1/2 X(1530)0 p- [email protected] 10 + X3/2 X(1530)0 p+ EPIPHANY, Cracow, January 6-8 2005. 8 X(1530)0 p: PRELIMINARY 0 p+ X(1530) No evidence ? for X+3/2 No cuts X(1530)0 p- X(1530) p+ No0evidence for X+3/2 pp ? [email protected] to X(1530)0 p+ X(1530)0 p- to X(1530)0 p > 3 + - 0.5 s GeV/c < dpbb < 1.5 s EPIPHANY, Cracow, January 6-8 2005. Existence of J=3/2 Q partner….?? [email protected] EPIPHANY, Cracow, January 6-8 2005. Check existence of J=3/2 X partner…. 1780 ?! 1860 [email protected] EPIPHANY, Cracow, January 6-8 2005. X5 and Q : members of a multiplet Reaction Energy CDF pp (Q,X)X 1.9 TeV TeV / s == 1.9 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 Experiment Q s+ WA89 X5 Q c+ S- A XX ES =340 GeV HERA-B pA FOCUS eBeO (Q,X)X E e=300 GeV (Q,X)X E p=920 GeV HERMES ed (Q,X)X E e=27.6GeV NA-49 pp (Q,X)X / s =17.6 GeV [email protected] EPIPHANY, Cracow, January 6-8 2005. M(pKS0 ) : 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 [email protected] < 15 MeV/c2 EPIPHANY, Cracow, January 6-8 2005. M(pKS0 ) : Preliminary results 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 + 80 < # of points (primary proton) < 145 ???? [email protected] EPIPHANY, Cracow, January 6-8 2005. 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. p for p Lpentaquark X W X- - states K other Look NA49 preliminary pp data Microcanonical statistical model F. M. Liu, H.Stoecker, K. Werner , hep-ph/0404156 [email protected] EPIPHANY, Cracow, January 6-8 2005. The NA49 Collaboration T. Antičić K. Kadija T. Šuša Ruđer Bošković Institute, Zagreb,Croatia [email protected] 1 EPIPHANY, Cracow, January 6-8 2005.