Recent Quarkonia Results from HERAB

1
Recent Quarkonia Results from HERA-B
International Workshop on Heavy Quarkonium
2006 June 27 30 2006, Brookhaven National
Laboratory
Martin zur Nedden Humboldt-Universität zu
Berlin for the HERA-B Kollaboration
2
The HERA-B Experiment
at the HERA storage ring
data taking up to march 2003
p A ? X , ?s 41.6 GeV

3
Contents

• Introduction
• HERA-B Detector
• Reference J/?-Production Cross Section
• Charmonium Production
• J/? Kinematical Distributions
• J/? Nuclear Dependence
• Polarisation Measurement
• ?(2S) Production
• ?c Production
• Beauty Production
• ? Production Cross Section
• Inclusive Beauty Production Cross Section

4
Part 1

• Introduction
• HERA-B Detector
• Reference J/?-Production Cross Section
• Charmonium Production
• J/? Kinematical Distributions
• J/? Nuclear Dependence
• Polarisation Measurement
• ?(2S) Production
• ?c Production
• Beauty Production
• ? Production Cross Section
• Inclusive Beauty Production Cross Section

5
Proton-Nucleus Interaction
PDF
6
Study of Charmonium Suppression

• state formation effects
• nuclear absorption
• comover absorption
• multiple scattering energy loss

• initial state effects
• shadowing (nuclear PDFs)
• parton energy loss
• intrinsic charm

HERA-B measurement of a for 2 wire materials
a ? 1 ? suppression
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xF-Dependence of Nuclear Suppression
formation time and length
? (xF) ? ? c ?
? ? (xF) boost of J/? w.r.t. nucleus
8
Part 2

• Introduction
• HERA-B Detektor
• Reference J/?-Production Cross Section
• Charmonium Production
• J/? Kinematical Distributions
• J/? Nuclear Dependence
• Polarisation Measurement
• ?(2S) Production
• ?c Production
• Beauty Production
• ? Production Cross Section
• Inclusive Beauty Production Cross Section

9
The HERA-B Detector
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The Dilepton Trigger
HERA-B detector data is read out and buffered
for 12 ?s(proton bunches cross every 96 ns, 0.5
interactions/BX)
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Di-Lepton triggered Data Sample
J/? ? ee- 108,000 J/? s 64 MeV/c2
J/? ? ?? 177,000 s 44 MeV/c2
J/?
3000 ?(2S)
?/?
?
?(2S)
1600 ?(2S)

• absolute cross sections from di-lepton triggered
  data
• need reference cross section

12
Part 3

• Introduction
• HERA-B Detector
• Reference J/?-Production Cross Section
• Charmonium Production
• J/? Kinematical Distributions
• J/? Nuclear Dependence
• Polarisation Measurement
• ?(2S) Production
• ?c Production
• Beauty Production
• ? Production Cross Section
• Inclusive Beauty Production Cross Section

13
J/? Production Cross Section from Minimum Bias
data
important for cross section normalisation of all
di-lepton triggered data based measurements
??-
ee-

• independent data sample
• efficiency and luminosity well understood
• ? systematic uncertainties small (usually
  dominant)

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J/? (MinB) A-Dependence and Results
a 0.96 ? 0.01 (fixed to E866)
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J/y (MinB) Combination with other Experiments
reference cross section is extracted by QCD
inspired fit including all available data (see
talk of A. Spengler)
Hera-B
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Part 4 a

• Introduction
• HERA-B Detector
• Reference J/?-Production Cross Section
• Charmonium Production
• J/? Kinematical Distributions
• J/? Nuclear Dependence
• Polarisation Measurement
• ?(2S) Production
• ?c Production
• Beauty Production
• ? production Cross Section
• Inclusive Beauty Production Cross Section

17
J/? pT Distributions (Nuclear Dependence)
standard fit
preliminary data (di-electron only), compared
with p-A results at similar energy (vs 38.8 GeV)
ltpTgt grows logarithmically with A
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J/? pT Distributions (Nuclear Dependence)
Cronin effect
ltpTgt grows with s ltpTgt ? 0.8 0.01?s
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J/? xF - Distribution
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J/? Nuclear Dependence
muon data only
data sample of 2 wire runs with different
materials (carbon/tungsten)
first measurement at xF lt -0.1 constant small
suppression
R.Vogt, Nucl.Phys.A700(2002)539.
? 0.969 0.003stat 0.021sys
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J/? Polarisation
usually only ???? is given
polarisation depends on reference system
E771, E672/E706
(Gottfried-Jackson)
E866
(Collins-Soper)
hadron CM
(hadron CM)
CDF
tan ? pT/MJ/? ? only for pT ? 0 are the
systems different
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Preliminary Polarisation Results
HCM GJ CS


large polarisation at pT0
? max. in CS frame ? natural system ?


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Part 4 b

• Introduction
• HERA-B Detector
• Reference J/?-Production Cross Section
• Charmonium Production
• J/? Kinematical Distributions
• J/? Nuclear Dependence
• Polarisation Measurement
• ?(2S) Production
• ?c Production
• Beauty Production
• ? production Cross Section
• Inclusive Beauty Production Cross Section

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?/ J/? Production Ratio
electron sample
muon sample
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Kinematical Distributions
Carbon
Tungsten
J/????
J/????
A-dependence??(xF) ?- ?
??, ee
CEM for color-1 nuclear absorption
NRQCD for color-1 -8 nuclear absorption
fit with const ??(E866)-0.0260.005
all consistent with no xF dependence. average of
E866 and NA50 is used ??(E866,
NA50)-0.0300.004
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FeynmanxF Dependence of ? Production Ratio
all targets included, correct for nuclear
effects with ??(E866, NA50)
NRQCD
CEM
data are consistent with both models (and with
no xF dependence)
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y production pT distributions
Carbon
Tungsten
J/????
J/????

• tendency for a wider pT distribution of ?'
• (increasing with A?)

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? Polarisation Measurement
result of
compatible with no polarisation difference
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Production Ratio ? / J/?
vs
in addition ?? and ee measurements yield
A
? improvement of B(?)
(better than current PDG value)
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Part 4 c

• Introduction
• HERA-B Detector
• Reference J/?-Production Cross Section
• Charmonium Production
• J/? Kinematical Distributions
• J/? Nuclear Dependence
• Polarisation Measurement
• ?(2S) Production
• ?c Production
• Beauty Production
• ? production Cross Section
• Inclusive Beauty Production Cross Section

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?c Production
selection
preliminary 2002/2003 data (di-muon sample)

• measurement
• fraction of J/?s from ?c
• kinematical distributions

background mixed events
after background subtraction
entries/(10 MeV/c2)
2000 data sample 370 74 ?cs (µµ-
ee-) R(?c) 0.32 0.06 0.04 Phys. Lett. B
561, 61 (2003)
m(µµ-?)-m(µµ-) GeV/c2
new data 40? bigger ?c statistics
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?c1 - ?c2 Separation
preliminary (a fraction of the di-muon sample)
ET(?) gt 0.4 GeV
further step separate different states by
varying the selection cuts
background mixed events
entries/(1 MeV/c2)
after background subtraction
measure the ?c2 / ?c1 production ratio
m(µµ-?)-m(µµ-) GeV/c2
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Production Cross Section Ratio R(?c)
preliminary evaluation (2002/2003 data)
based on 1300 ?cs reconstructed in the di-muon
channel (less than 10 of the total statistics)
(21 5) of the produced J/?s come from ?c
decays
E771 (p-Si)
E369/ 610/ 673 (p-Be)
p-A
ISR (p-p)
2000
expected final precision
2002/3 prelim.
E705 (p-Li)
HERA-B
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Part 5 a

• Introduction
• HERA-B Detector
• Reference J/?-Production Cross Section
• Charmonium Production
• J/? Kinematical Distributions
• J/? Nuclear Dependence
• Polarisation Measurement
• ?(2S) Production
• ?c Production
• Beauty Production
• ? production Cross Section
• Inclusive Beauty Production Cross Section

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Beauty Production at HERA-B
RD ?531?4 ?m
detached vertex analysis
open
pA ?b?b X J/? X e
e- , ? ?-
hidden
invariant mass analysis
Cross sections normalised to prompt J/? using
the NRQCD supported evaluation ?(pN ? J/? X)
(502 ? 44) nb/nucleon (with ? 0.96 ? 0.01)

• pA ? ? X
• e e- , ??-

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Hidden Beauty Production
muon channel 30.8 7.4
electron channel 75 14
DY
DY
comb
comb
Fit A (?(1S) ?(2S) ?(3S)) B Drell-Yan
combinatorial
?(1S) ?(2S) ?(3S) fixed to E605 results
shape from MC
from like-sign pairs
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Hidden Beauty Production Results
normalized to J/? refernece cross section
fit modified Craigie
? NLO CEM
data are compatible with ?1
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Part 5 b

• Introduction
• HERA-B Detector
• Reference J/?-Production Cross Section
• Charmonium Production
• J/? Kinematical Distributions
• J/? Nuclear Dependence
• Polarisation Measurement
• ?(2S) Production
• ?c Production
• Beauty Production
• ? production Cross Section
• Inclusive Beauty Production Cross Section

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Detached Vertex Analysis
B meson has a long life time ( 9 mm at HERA-B
kinematics) 0.5 mm dilepton vertex
resolution J/? from a B decay will be detached
from primary interaction
downstream
upstream
analysis cuts - decay lenght (?z) - impact
parameter
normalization on the inclusive prompt J/? cross
section. ? systematic error minimization
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Open Beauty Data Sample

• analysis of 2002/03 data
• ee- and ??- triggered data
• C, W, Ti targets (??1 for bb)
• J/? acceptance -0.35 lt xF lt 0.15
• (90 of bb cross section)

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B Flavour Confirmation
t 1.39 0.19 ps

• Long lived candidates around J/? mass
• B lifetime compatible with expected 1.54 ps (PDG)

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Principle of the Cross Section Measurement

• measurement relative to prompt J/?-cross section
• minimize systematics uncertainties
• independent of lumi determination
• mostly independent of production model and J/?
  cross section

atomic number cross section dependence
? in detector acceptance
?R relative efficiency ?1
sum over target materials C,W,Ti
B selection efficiency from MC
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Open Beauty Production R??
relative to prompt J/? to minimize uncertainties
from efficiencies, luminosity
2000 data
combined result of 2000 and 2002/3 data
?R?? 0.032 ? 0.005stat ? 0.004sys
(syst. error mainly from B(b?J/?))
PHYSICAL REVIEW D 73, 052005 (2006)

2000 data Eur. Phys.J. C26 (2003) 345
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Production Cross Section
Relative to prompt J/? to minimize uncertainties
from efficiencies, luminosity
normalizing to ?J/? from Maltoni et al. ?(pN ?
J/? X) (502 ? 44) nb/N

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Summary

• HERA-B collected 300000 J/? and 220 Mio min.bias
  events on different nuclei
• Results on charmonium production (partly
  preliminary)
• J/ ? cross section
• J/ ? xF and pT distributions in a new negative
  xF range
• J/? A dependence demonstrate a flat behavior in
  this region
• Fraction of ?c and ?(2S) yields relative to J/?
  
• Open and hidden beauty cross sections
• Final results on J/?, ?, b-cross section, ?c and
  ?(2S) are/will be publisched during 2006