1. Multi-hyperons in p-p events X- X+ X(1530)0 X(1530)0 W- W+
Tome Anticic
Kreso Kadija
Tatjana Susa
Vedran Nikolic
1996
1.03 M
1999
1.21 M
Rudjer Boskovic Institute
Zagreb, Croatia
2000
2.67 M
2001
0.67 M
2002
2.84 M
NA49 collaboration meting, Krakow, 2008

2. Data corrected with millepede Main vertex with improved method
X signal
13 parameter fitter
3 MeV/bin
Data corrected with millepede
Main vertex with improved method
about 3800 X-
about 1200 X+

3. X cuts X cuts X p p all tracks need at least 8 VTPC points
Lrap < -1.0
|Lim | < 8 MeV
(by/0.5)2 + (bx)2 < 12
-1.0 < Lrap < -0.5
|Lim | < 12 MeV X
-0.5 < Lrap < 0.5
|Lim | < 18 MeV
(pby/0.2)2 + (pbx/0.4)2 > 0.5 2
0.5 < Lrap
|Lim | < 20 MeV p
proton
Xrap < -1.75
zX - zmain < 0 cm
-1.75< Xrap < 0.75
zX - zmain < 5 cm p
0.75 < Xrap < 1.25
zX - zmain < 12 cm
1.25 < XXap
zX - zmain < 20 cm
all tracks need at least 8 VTPC points
Spectra with minmal cuts:
5 cm vertex
20 MeV around L mass
No impact cuts
all tracks are +- 3 s (dE/dX)
Rejected spectra due to above cuts

4. Includes contribution of neutral lambda decay
X acceptance
Includes contribution of neutral lambda decay

5. X- signal- rapidity mb mb
rapidity pt

6. X- signal,error and temperature
Rapidity
Signal
(mb)
Statistical error
Systematic error
Temperature
(MeV)
Error
-1.5
0.0160
0.0022
0.0009
-1.0
0.0229
0.0014
0.0004
152 3
-0.5
0.0298
0.0012
0.0006
169
0.0
0.0333
0.0013
0.0005
155
0.5
0.0308
0.0015
170 4
1.0
0.0225
0.0019 5
1.5
0.0145
0.0039

7. X- cross section
s= mb
Venus

8. X- signal- inv. xf

9. X- signal- xf

10. X+ - rapidity mb mb
rapidity pt

11. X+ signal and temperature
Rapidity
Signal
(mb)
Statistical error
Systematic error
Temperature
(MeV)
Error
-1.5
0.0012
-1.0
-0.5
133 3
0.0
147 4
0.5
129
1.0
0.0056
0.0011
0.0003

12. Rapidity- data and Venus
X+ – cross section mb
s= mb
Rapidity- data and Venus
Venus

13. X+ - inv xf mb mb

14. X+ - xf

15. Prim track selection: D c2 < 0.5 between ttrack and rtrack
X(1530)0
2.5 MeV binning
About 550 X(1530)0
selection: +- 6 MeV around Xmass if Xrap < 0.25, MeV otherwise
Prim track selection: D c2 < 0.5 between ttrack and rtrack

16. X(1530)0
T =

17. X(1530)0 signal and temperature
Rapidity
Signal
(mb)
Statistical error
Systematic error
-1.0
0.0050
0.0012
0.0005
-0.5
0.0066
0.0010
0.0006
0.0
0.0083
0.5
0.0059
0.0011
1.0
0.0049
0.0015

18. X(1530)0 cross section
s= mb
Venus

19. X(1530)0 xf and inv. xf
Invariant xf xf

20. Central rapidity only +- 0.25
X(1530)0
Central rapidity only
scentralrap= mb

21. DATA(after all other cuts)
W : additional cuts
zW - zmain > 12 cm
DATA(after all other cuts) MC
Rap = -0.5
Ptot of Kaon candidate
Ptot of Kaon

22. Asymetric dedx cut on Kaon (pion main contaminant)
W: additional cuts II
Asymetric dedx cut on Kaon (pion main contaminant)
Rap = -0.5
Rap = 0
Rap = 0.5

23. Inv mass W- Rap = -0.5 Rap = 0.0 Rap = 0.5 about 70 W-

24. W- pt only 1 rap bin, from -1.25 to 1.25 Invariant xf T = 163 +- 4
rapidity

25. W- -0.5 0.0 0.5 Rapidity Signal (mb) Statistical error
Systematic error
-0.5
0.0
0.5

26. W-
s= mb
Invariant xf
Venus

27. W- inv. Xf and xf
Invariant xf xf

28. W+
scentralrap= mb

29. Things to come Things to be in the next paper:
singly strange hyperon paper-
L, L(1520), S(1385)
What about K*, Ks ?
pA also worked on in parallel

30. L new pt and rapidity acceptance
previous rap range up to
pt at midrap
previous pt range up to 1.35 GeV
pt = 1.5 GeV
pt = 1.7 GeV
all L
pt = 1.9 GeV
pt = 2.1 GeV
rap = - 2.0

31. More hyperons
L(1520)

32. S(1385)+ -> L p+ S(1385)- -> L p-
Width ~ 38 MeV

33. S(1385)+, S(1385)-
~ 4000
~ 6000

34. S(1385)+ _
Rap -1.0
Rap -1.5
Rap -0.5
Rap 0.0

35. S(1385)+ _
Rap 0.5
Rap 1.0
Rap 1.5

36. S(1385)+/- counts, ratios (NO ERRORS, NO MC CORRECTION FACTOR)
rapidity

37. S(1385)+ pt
0.1
0.3
0.5
0.9
1.1
0.7

38. S(1385)+ pt
1.3
1.5

39. S(1385)+ , S(1385)-

40. Backup slides

41. Omega II DATA MC Impact of Omega Impact of Kaon
(Wby/0.5)2 + (Wbx)2 < 12
Impact of Kaon
(Kby/0.2)2 + (Kbx/0.4)2 > 0.5 2

42. Inv mass W- Rap = 0.0 Rap = -1.0 Rap = 0.5 Rap = -0.5 Rap = 1.0

43. Omega/AntiOmega cuts (same)
DATA MC
Rap = -1
Rap = -0.5
Ptot of Kaon

44. Inv mass W+

45. X spectra in the 1999 data set
new X-
old X-

46. aomega

47. Experimental data using Gap TPC
S4 trigger effect
Min bias Venus events
Experimental data using Gap TPC

48. X reconstruction correction factors
improved R3D/main vertex/ X finder/ geometry
standard R3D/main vertex/ X finder/ geometry
The correction factors include the loss due to neutral L decays, as well as the loss due to 18 cm cut from the 20 cm target

49. New residuals, new impact parameters
new L
forward rap.
(1999 data)
Impact parameter in x
Impact parameter in y
old L
forward rap.

50. Cross section determination
weight = gTriggerCS(year)*nMcOrig/nMcRec/nPPEvents
nPPEvents=nFullEvents*(1.-rateEmpty/rateFull)

51. Gauss main vertex fit R3D main vertex accuracy
Gauss main vertex accuracy
R3D main vertex accuracy vs track number
Comparison
Gauss main vertex accuracy vs track number
Gauss significantly better
Mean closer to zero
RMS better by 30 %
Much smaller tails