Status of the HERA-B Analysis 58th PRC Open session, May 26, 2005

1
Status of the HERA-B Analysis 58th PRC Open
session, May 26, 2005
Hermann Kolanoski Humboldt Universität zu Berlin
and DESY Zeuthen for the HERA-B Collaboration

• Data samples
• Physics topics
• Selected topics
• J/y cross section
• y(2S) production
• A-dependence of J/y production
• ?c production
• Summary

2
Data samples

• Analysis of data taken from Oct. 2002 to Feb.
  2003
• 150 M di-lepton trigger events
• 210 M minimum bias events
• 35 M hard photon trigger events
• 60 M glueball trigger events

? 300 000 J/? ee- ??-
Different target wires, mainly C, Ti, W
proton-nucleon CM energy
3
Analysis Topics
published (2002/03 only)

• Upper limit on BR(Do ? ????) Phys.Lett.B596173-1
  83,2004
• Pentaquark limits (pKS, ??) Phys.Rev.Lett. 93
  (2004) 212003
• bb production cross section
• ? production cross section
• Production of ? and K mesons
• J/? production cross section
• D/Do production ratio
• Production ratio ?(2S) / J/?
• J/? differential distributions
• Charmonium production A-dependence
• ?c production, A dependence
• high-pt photons
• ? polarization
• Vo differential and total cross section
• Hyperon production

needs J/? ref. cross section
draft stage
analysis note in preparation
preliminary results available
needs more work
4
J/y Cross Section from Min. Bias Data
relatively low statistics, but no trigger
uncertainty
ee-
??-
A lot of work for lumi studies publication in
preparation
W
(prelim.)
Ti
average over A with a 0.96?0.01 fixed
HERA-B 1.7 x higher than E771 / 789 extrapolated
to this energy region (!?)
C
A
Important for cross section normalization of
di-lepton triggered data
5
Study of J/? Cross Section Parametrisations
Fit of cross section data currently studied with
F.Maltoni using NRQCD model
Fits rather stable w.r.t. changes in model input
(PDFs, MEs, ..)
Biggest problem inconsistent exp.data
(prelim., study ongoing)
(previously from E771 and E789 (357 ? 8 ? 27)
nb/nucleon)
6
Results for Beauty Cross Sections have to be
scaled by new J/? reference cross section
(prelim.)
Plots still normalized to ?J/? from E771 and
E789 will change by ?1.4
(prelim.)
7
Study of Charmonium Suppressionas input for QGP
searches in heavy ion collisions
Kinematical distributions (xF, pT, polarization)
derived from - NRQCD for nucleon-nucleon
reactions - models for nuclear effects in pA
reactions
xF Lf fm
0.2 20
0.0 7
-0.2 2
xF measures the formation length of the ccg
state
Lf ? 0.3 fm ? ??
scc ?s0 ? Aa a ? 1 ? suppression

• xF gt 0 ccg forms a bound state outside the
  nucleus
• xF lt 0 ccg forms a bound state inside the
  nucleus

8
A dependence of J/? Production ?(xF), ?(pT)
dominant syst. wire sharing 2 decrease to
1 (?)
2-wire runs (C, W), ??- data
HERA-B now absolutely normalized
extending the range of measurements to xF 0.35

• Systematic studies ongoing
• electron channel being finalized

9
y(2S) Production s(y(2S)) / s(J/y)
??- data
W
C
Ti
10
xF distributions
preliminary
preliminary
preliminary

• Ratio
• In agreement with NRQCD
• almost constant vs xF

fitted by a bxF
11
Dependence on pT
preliminary
preliminary
Power-low is suitable for the fitting
?(2S) appears to have a wider pT distribution ?
nuclear effects different for radial excitation?
12
A- and s-Dependence of s(y(2S)) / s(J/y)
Agrees with E866 value a(y(2S)) -
a(J/y)-0.0260.005
preliminary
Results from ??- data
preliminary
Similar results from ee- data
13
?c / J/? production ratio
observed in radiative decay
Background shape from event mixing
??- channel, results from full data set now
available
carbon
all targets
tungsten
?m m(ll-?) m(ll-) GeV/c2
14
?c production results
R(?c) 0.210.05 (prel.)

• Systematic studies ongoing
• background determination
• ? efficiency
• electron channel (similar results)
• dependence on polarization
• The efficiencies for all possible polarization
  states have been calculated and differ by less
  than 10.

from only 10 of 2002/03 data
z
ECMS (GeV)
15
Conclusion

• HERA-B has a considerable list of interesting
  topics under study which should be published.
• The number of active collaboration members is
  decreasing as expected but the main analysis
  topics should be reasonably covered.
• The goal is to produce draft publications by end
  of this year for most of the topics (O(10), for
  sure 4 publications this summer)