charmonium production in media
DESCRIPTION
Charmonium Production in Media. Quarkonia in Media / Production. International Workshop on Heavy Quarkonia 2008 December 2 – 5 2008, Nara Women University, Japan. Martin zur Nedden Humboldt-Universit ät zu Berlin for the HERA-B Collaboration. The HERA-B Experiment. 920 GeV protons. - PowerPoint PPT PresentationTRANSCRIPT
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Martin zur Nedden, HU Berlin QWG Meeting, Nara 2008, p. 1Charmonium Production in Media
Charmonium Production in Media
Martin zur NeddenHumboldt-Universität zu Berlin
for the HERA-B Collaboration
International Workshop on
Heavy Quarkonia 2008December 2 – 5 2008, Nara Women University, Japan
Quarkonia in Media / Production
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Martin zur Nedden, HU Berlin QWG Meeting, Nara 2008, p. 2Charmonium Production in Media
920 GeV protons
p + A X , s = 41.6 GeV
The HERA-B Experiment
data taking up to march 2003
Spectrometer at the HERA storage ring: proton-fixed target
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Martin zur Nedden, HU Berlin QWG Meeting, Nara 2008, p. 3Charmonium Production in Media
Contents
• Introduction• HERA-B Detector• J/ψ: Kinematical Distributions• J/ψ: Nuclear Dependence• χc Production
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Martin zur Nedden, HU Berlin QWG Meeting, Nara 2008, p. 4Charmonium Production in Media
Contents: Part 1
• Introduction• HERA-B Detector• J/ψ: Kinematical Distributions• J/ψ: Nuclear Dependence• χc Production
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Martin zur Nedden, HU Berlin QWG Meeting, Nara 2008, p. 5Charmonium Production in Media
Hadronic Production of Heavy Quarks
ij
FRijFjFi dxdxppxfxf 2122
212
22
1 ),,,(ˆ),(),(
production in hadronic interaction
Parton-Density-Functionwithin the hadron
partoniccross setion
hadronisation:formation ofhadrons withheavy quarksor quarkonia stats
factorisation of the process
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Martin zur Nedden, HU Berlin QWG Meeting, Nara 2008, p. 6Charmonium Production in Media
Quarkonia Formation
Hadronization: formation of Quarkonia (J/ψ, ψ’, χc, Υ)long distance (~1/(mcv)) process:non-perturbative calculations andinput from experiments needed, model dependence:CSM, COM, CEM, NRQCD
qq formation: production of heavy quarks in mediashort distance (~1/mc) / high momentum process:perturbative calculation
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Martin zur Nedden, HU Berlin QWG Meeting, Nara 2008, p. 7Charmonium Production in Media
based on Glauber-model:
≠ 1 „dependence”
Nuclear Effects for Charmonium Production
p
μ/e+
μ/e-
J/
final state formation effects:• nuclear absorption• comover absorption• multiple scattering + energy lossinitial state effects:
• shadowing (nuclear PDFs)• parton energy loss • intrinsic charm
ApNpA
HERA-B: acsess to production in media measurement of using C and W wires:
C
W
W
C
W
C
C
W
C
W
C
W
AA
LL
NN
AA
ln
ln
ln
ln
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Martin zur Nedden, HU Berlin QWG Meeting, Nara 2008, p. 8Charmonium Production in Media
xF-Dependence of Nuclear Effects
for c = 0.5 fm
xF [fm]
0.2 30
0 10
-0.2 4
p
μ/e+
μ/e-
J/
formation time and length: (xF) = c
= (xF) boost of J/ w.r.t. nucleus
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Martin zur Nedden, HU Berlin QWG Meeting, Nara 2008, p. 9Charmonium Production in Media
Contents: Part 2
• Introduction• HERA-B Detector• J/ψ: Kinematical Distributions• J/ψ: Nuclear Dependence• χc Production
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Martin zur Nedden, HU Berlin QWG Meeting, Nara 2008, p. 10Charmonium Production in Media
HERA-B Detector and Trigger
p-beam
z [cm]
C
Ti
W
Muon-TriggerElectron-Trigger
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Martin zur Nedden, HU Berlin QWG Meeting, Nara 2008, p. 11Charmonium Production in Media
•150 M di-lepton trigger events (e+e- / μ+μ- triggers) ~ 300 000 J/ψ ~ 15 000 c
~ 5 000 ψ’
• 210 M minimum bias events
HERA-B Data Samples
m(ee) [GeV/c2]
en
trie
s/(3
0 M
eV
/c2)
103
104
2.5 3.0 3.5 4.0
~ 120 000 J/ψ ~ 2 200 ψ′
σJ/ψ ~ 64 MeV
~ 120 000 J/ψ ~ 2 200 ψ′
σJ/ψ ~ 64 MeV
e+e-
J/J/ψψJ/J/ψψ
ψ′ψ′ψ′ψ′
en
trie
s/(2
5 M
eV
/c2)
m(μμ) [GeV/c2]
103
104
2.8 3.2 3.6 4.0
μ+μ-
J/J/ψψJ/J/ψψ
ψ′ψ′ψ′ψ′
~ 170 000 J/ψ ~ 3 000 ψ′
σJ/ψ ~ 44 MeV
~ 170 000 J/ψ ~ 3 000 ψ′
σJ/ψ ~ 44 MeV
Three target materials:pC,pW and pTi collisions
absolute cross section measurements for di-lepton triggered data need independent reference cross section
measured with minBias events: σ(J/ψ) = (502 ± 44) nb/nucl.
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Martin zur Nedden, HU Berlin QWG Meeting, Nara 2008, p. 12Charmonium Production in Media
Contents: Part 3
• Introduction• HERA-B Detector• J/ψ: Kinematical Distributions• J/ψ: Nuclear Dependence• χc Production
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Martin zur Nedden, HU Berlin QWG Meeting, Nara 2008, p. 13Charmonium Production in Media
J/ pT Distributions
HERA-B combined result
Increase of <pT2> with
A (radius of nucleus):
linear dependence on the nuclear path length of the incident parton
GeV1.29/4.27s
GeV8.38s
GeV6.41s
NA50
E672/706/771/789
HERA-B
2
2
2
11
T
TT
T p
pp
dp
dN
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Martin zur Nedden, HU Berlin QWG Meeting, Nara 2008, p. 14Charmonium Production in Media
J/ψ xF - Distribution
Fx
FF
F w
xx
dx
dN2lnexp
wxF : widthΔxF : shift
width increasing withRadius of nucleus
shift increasing withRadius of nucleus
• pT distribution:• increase of <pT
2> with radius• xF distribution:
• increasing width and shift with radiusboth effects compatible with initial state energy loss
HERA-B combined result
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Martin zur Nedden, HU Berlin QWG Meeting, Nara 2008, p. 15Charmonium Production in Media
Contents: Part 4
• Introduction• HERA-B Detector• J/ψ: Kinematical Distributions• J/ψ: Nuclear Dependence• χc Production
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Martin zur Nedden, HU Berlin QWG Meeting, Nara 2008, p. 16Charmonium Production in Media
Measurement of Nuclear Dependence
TF
C
C
TF
W
W
C
W
TF
dpdx
ddpdx
d
A
Apx
/1
/1
ln
ln
1)/(
XJpAA /
sys.stat. 016.0004.0981.0
C
W
C
W
A
A
nuclear dependence parameter α extracted from the ratioof carbon and tungsten J/ψ production cross sections
Final result form HERA-B:
result based on double wire runs only
Measurement of the xF and pT dependence of α based on full data sample:
Using the measured kinematical distributions of carbon and tungsten (normalized)(full data sample of single and double wire runs)
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Martin zur Nedden, HU Berlin QWG Meeting, Nara 2008, p. 17Charmonium Production in Media
Nuclear Dependence Measurement: pT
Good agreement of E866 anHERA-B measurement in thecommon region of pT
pT broadening effect as seen by E866 confirmed
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Martin zur Nedden, HU Berlin QWG Meeting, Nara 2008, p. 18Charmonium Production in Media
Theoretical Models for xF Dependence
Separate description and integration:
• final state absorption• interaction with co-movers• energy loss (EL)• shadowing of nuclear PDFs• intrinsic charm quark components (IC)
Nuclear Parton Density Functions:
• Eskola, Kolhinen, Salgado (EKS, Eur.Phys.JC9(1999)61)• scale dependence of a proton within a nucleon via DGLAP• initial PDF from CTEQ4L and LO-GRV
• Eskola, Paukkunen, Salgado (EPS, arXiv:0802.0139)• improved leading order DGLAP including NLO
• Hirai, Kumano, Nagai (HKN, Phys.Rev.C70(2004)044905)• nuclear structure functions and Drell-Yan cross sections• weak anti-shadowing at negative xF
Initial state energy loss:
• Gavin, Milana (GM, Phys.Rev.Lett.68(1992)1834)• based on multiple scattering approach• elastic scatterings of quarks and gluons
• Brodsky, Hoyer (BH, Phys.Lett.B298(1993)165)• modification of GM
Model calculation by R. Vogt:
- Phys.Rev.C61(2000)035203- Phys.Rev.C71(2005)054902- Private communication
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Martin zur Nedden, HU Berlin QWG Meeting, Nara 2008, p. 19Charmonium Production in Media
Theoretical Descriptions: Overview
All calculations done by Ramona Vogt in 2007/2008
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Martin zur Nedden, HU Berlin QWG Meeting, Nara 2008, p. 20Charmonium Production in Media
Nuclear Dependence Measurement: xF
average α measurement form HERA-B:
sysstat 016.0004.0981.0 .
Final result form HERA-B, to be published in Eur.Phys.J
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Martin zur Nedden, HU Berlin QWG Meeting, Nara 2008, p. 21Charmonium Production in Media
Reggeon Phenomenology Model
Boreskov and Kaidalov (JEPT Lett.D77(2003)599):
predicts anti-screening effects in negative xF region- color less state containing quarks (i.e. D-Mesons) propagates trough the nucleus- large size (consisting of D-mesons), large interaction cross section: energy loss- J/ψ projected out of energy dependent color-less state
HERA-BE866
cc
HERA-B result within uncertainties qualitatively compatible
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Martin zur Nedden, HU Berlin QWG Meeting, Nara 2008, p. 22Charmonium Production in Media
Contents: Part 5
• Introduction• HERA-B Detector• J/ψ: Kinematical Distributions• J/ψ: Nuclear Dependence• χc Production
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Martin zur Nedden, HU Berlin QWG Meeting, Nara 2008, p. 23Charmonium Production in Media
χc Production
)/(
)/()(2
1,
J
JBRR i
cic
c
Relative measurement of χc to J/ψ production
eeJ
Jc
//
/
HERA-B:
Selection by γ Selection (Eγ) andinvariant mass measurement: )()( llMllMM
• making use of J/ψ production cross section from min.Bias data• disentangle χc1 and χc2 by double Gaussian fits: separate cross section measurements• background subtraction by mixed events• separate analysis for electrons and muons• full statistics in both channels: 15000
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Martin zur Nedden, HU Berlin QWG Meeting, Nara 2008, p. 24Charmonium Production in Media
χc Event Counting
electronsmuons
Separation of χc1 and χc2 in the ΔM spectra:• double Gaussian fit with some fixed parameters predicted by MC• free parameters are the ratio and sum of event numbers
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Martin zur Nedden, HU Berlin QWG Meeting, Nara 2008, p. 25Charmonium Production in Media
A-Dependence
C
W
C
W
J
A
A
R
R
c
c
c
log
log
/
averaged result of
HERA-B:
Δα = 0.05 ± 0.04
Atomic mass number dependence:
• same principle as for J/ψ• no significant difference in A-dependence within the statistical limits
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Martin zur Nedden, HU Berlin QWG Meeting, Nara 2008, p. 26Charmonium Production in Media
Production Cross Section Ratio R(c)
[GeV]s
CDF CDF ((p-pp-p))
ISR ISR ((p-pp-p))
E771 E771 ((p-p-SiSi))
E705 E705 ((p-p-LiLi))
E369/ E369/ 610/ 610/ 673 673
((p-p-BeBe))
2002/3 final
ππ-A-A
Final result: Rχc = (18.8 ± 2.8)%
of the produced J/ψ’s come from χc decays
HERA-B
HERA-B 2000
[%]c
R
97015200)(#
6605630)(#
7109570)(#
tot
ee
c
c
c
available statistics:
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Martin zur Nedden, HU Berlin QWG Meeting, Nara 2008, p. 27Charmonium Production in Media
Final Results of χc
eon61)nb/nucl(231)(
nb/nucleon)35133()(
23.057.0)(
)(
04.005.0
40.002.1
188.0
c2
1
2
1
12
028.0026.0
c
c
c
R
Rc
Final result form HERA-B, accepted for Phys.Rev.D (arXiv:0807.2167)
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Martin zur Nedden, HU Berlin QWG Meeting, Nara 2008, p. 28Charmonium Production in Media
Summary
HERA-B collected 300000 J/, 15000 χc and 220 Mio minimum bias events on nuclear targets (mainly carbon and tungsten)
Final Results on charmonium production:
• J/: inclusive production cross section• J/: xF and pT distributions in a new negative xF range J/: nuclear dependence: tendency of enhancement in at xF <0• c : production ratio, disentanglement of χc1 and χc2
Final results on kinematics of J/ production, nuclear dependence of J/ψ and c production are final and published (during 2008)