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Rc measurements & vector charmonia
Changzheng YUAN
IHEP, Beijing
(BES & Belle collaborations)
Fermilab, May 18, 2010
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Outline
• Introduction
• Rc measurements– R scan: BESII & CLEOc + prior BES
– ISR: Belle & BaBar
• Vector charmonium spectroscopy
• Summary
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High mass vector charmoniaToo many vectors!
What is the nature of the newly observed states?
Charmonium?Hybrid?Hadro-charmonium?Tetraquark?Molecular?…
Can we answer?
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R & Rc
All the vector charmonium states appear in this plot (between 3.0 and 4.7 GeV!). We extract resonant parameters from these (and more) Rc data!
From PDG
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Outline
• Introduction
• Rc measurements– R scan: BESII & CLEOc + prior BES
– ISR: Belle & BaBar
• Vector charmonium spectroscopy
• Summary
-e
+e*γ
ISRγ
c
cJPC = 1--
ψ’, ψ’’, Y…
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BESII R Scan (2-5 GeV)
[PRL84, 594 (2000)][PRL88, 101802 (2002)][PLB677, 239 (2009)]
6 points: uncertainty 6-12%85 points: uncertainty 6.6%
3 points: uncertainty 3-4%: Ruds~ 2.14Rc = R-Ruds
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BESII R Scan (around ψ(3773))
PRL97, 262001 (2006)68 points
uncertainty 4-5%Rc = Rhad-Ruds
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CLEOc R Scan (3.97-4.26 GeV)PRD80, 072001 (2009)13 points
uncertainty 2-3%R = Rc+Ruds
(Ruds =2.285)
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Rc Scan (3.97-4.26 GeV)CLEOcPRD80, 072001 (2009)
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Belle Rc Scan via ISR
Continuous energy scan. Full mass range in one experiment, errors are large due to low efficiency of ISR & D tag.
uncertainty 10-50%
PRL100, 062001 (2008)
PRD77, 011103 (2008)
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Belle Rc Scan via ISR
Summed by G. Pakhlova.Still missing modes (small Xs):1. Charm strange meson pairs2. Charmonium+hadron/γ3. Charm baryons except Λc
PRL101, 172001 (2008)
PRD80, 091101 (2009)
Rc=Σσ
(cha
rm)/σ
(μμ)
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Belle Rc Scan via ISR
(charmonium+hadrons)
Full reconstruction of the hadronic system, no ISR photon tag
PRL99, 182004 (2007)
PRL99, 142002 (2007)
PRD77, 011105 (2008)
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BaBar Rc Scan via ISRPRD76, 111105 (2007)
Babar fully reconstruct D- & Dbardecays
ISR photon detection not required
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BaBar Rc Scan via ISR
PRD79, 092001 (2009)
Summed of DDbar, DD*, and D*D* cross sections.
Cro
ss s
ectio
n (n
b)
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BaBar Rc Scan via ISR(charmonium+hadrons)
Only reported mode from BaBar, ππJ/ψ results not published
PRL98, 212001 (2007)
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A few comments on Rc measurements• Already lots of data (BES, Belle, BaBar, CLEOc)• Precisions are not very high, especially for exclusive
charm final states• Charmed strange final states in full range still
missing (CLEOc at E<4.3 GeV)• More charmonium final states from Belle/BaBar full
data sample?• BESIII scan with high statistics
– 1 fb-1/year now, expect 5 fb-1/year in ~3 years– Can measure all final states with cross section > 10 pb– May start R scan (E=3-4.6 GeV) in 3-4 years
• Do you have any new idea? Join us or tell us!
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Outline
• Introduction
• Rc measurements– R scan: BESII & CLEOc + prior BES
– ISR: Belle & BaBar
• Vector charmonium spectroscopy
• Summary
-e
+e*γ
ISRγ
c
cJPC = 1--
ψ’, ψ’’, Y…
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Incoherent sum of 3 BWs• BES data (M, Γ, Γee)
– ψ(4040)• 4040 ± 1 MeV• 89 ± 6 MeV• 0.91 ± 0.13 keV
– ψ(4160)• 4155 ± 5 MeV• 107 ± 16 MeV• 0.84 ± 0.13 keV
– ψ(4415)• 4429 ± 9 MeV• 118 ± 35 MeV• 0.64 ±0.23 keV
PRD72, 017501 (2005)
Fit by K.K.Seth
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Fit by BES
BES, PLB660, 315 (2008)
Amplitude of r f
Mass dependent width
Coherent sum of 4 BWs
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Fit by BES
C.L. =31.8%
BES, PLB660, 315 (2008)
Contribution from each component
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Final results from BES
BES, PLB660, 315 (2008)
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Multiple solutions
CZY, X.H. Mo, P. Wang, arXiv:0911.4791Same problem exists in fitting Rc data
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Multiple solutions in R-fit
X.H. Mo, CZY, P. Wang, in preparation
Simplified parameterization of the resonance amplitudes
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Multiple solutions in BES data
4 solutions with the same fit quality!
BES official fit is only one of the four possible solutions!
X.H. Mo, CZY, P. Wang, in preparation
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Multiple solutions in BES data
X.H. Mo, CZY, P. Wang, in preparation
Same for all solutions
Sol. I (same as BES)
Sol. II
Sol.III
Sol. IV
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Multiple solutions in BES dataLeptonic partial widths
are very different in different solutions.
Toy MC (100 points, 1% error) shows that when data are more precise, the difference in Γeecould be very significant.
Which solution is PHYSICS?
X.H. Mo, CZY, P. Wang, in preparation
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Choose one from multiple solutions
Toy MC with 100 data points with 1% relative error in R measurement.
Which solution should we choose?
X.H. Mo, CZY, P. Wang, in preparation
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Summary• Rc measurements
– R scan: BESII & CLEOc + prior BES– ISR: Belle & BaBar
• Vector charmonium spectroscopy– How to describe the resonances– Use not only inclusive data, but also charm cross
sections– Multiple solutions
• Future– More data from BESIII (<3% error in R)– Better models– Fit ψ’s and Y’s simultaneously
Thanks a lot!
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e+e-→ π+π-ψ(2S) via ISR
Y(4360) – consistent with BaBarY(4660) – NEW (5.8σ)
Belle: X.L. Wang & C.Z.Y et al., PRL99, 142002 (2007)
Two solutionsSystematics±9
.5%
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e+e-→ π+π-J/ψ via ISR• Non resonant J/ψππ ?• Re-scattering ee → D(*)D(*) → J/ψππ ?• Another broad state ?
– Check the latter hypothesis and influence of interference of Y(4260) with non-Y contribution:
– Fit with 2 coherent BWs– Two-fold ambiguity in amplitude
(constructive-destructive interference) + model uncertainty due to ψ’ tail
2-BW fit with interference better describes the data: Y(4260) parameters are different (especially peak cross section – large uncertainty)
Belle: C.Z.Y & C.P. Shen et al., PRL99, 182004 (2007)
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Multiple solutions
CZY, X.H. Mo, P. Wang, arXiv:0911.4791