1. Galina Pakhlova ITEP&Belle
International Workshop on Heavy Quarkonia 2008
2-5 December 2008, Nara Women's University
Galina Pakhlova
ITEP&Belle
Charm components of R using ISR at Belle

2. Two main reasons to know charm components of R
R(s) = σ(e+e–→hadrons, s)/ σ(e+e–→μ+μ–, s)
Two main reasons to know charm components of R
To shed light on the nature of the charmoniumlike “1–– family” with masses above open charm threshold
To provide model independent information on the parameters of the JPC = 1–– charmonium states spectrum above open charm threshold
Galina Pakhlova

3. Y(4260)
Y(4325)
Y(4008)
Y(4660)
Curious 1– – family
Galina Pakhlova 3

4. e+e−→ 1– – final states via ISRc e- 
s=E2cm-2EEcm e+ e–
1– –
ISR physics at B-factories
Quantum numbers of final states are fixed JPC = 1– –
Continuous ISR spectrum: access to the whole s interval
em suppression compensated by huge luminosity
comparable sensitivity to energy scanning (CLEOc, BES
Galina Pakhlova

5. Two or one states in e+e–→J/π+π– γISR ?
Y(4260)
454 fb-1
344±39 ev
Y(4008)
arXiv:
NEW
Two or one states in e+e–→J/π+π– γISR ?
< % CL
7.5±0.9±0.8
Br(J/π+π–)Γee , eV
Solution1 Y(4008) Solution2
Solution1 Y(4260) Solution2
Absence of open charm production
is inconsistent with conventional charmonium
Galina Pakhlova

6. e+e–→(2S) π+π– γISR Y(4360), Y(4660) ...
Y(4360)→(2S)ππ
PRL 98, (2007)
298 fb-1
Y(4660) ?
Y(4360) 8σ
Y(4660)
5.8
670 fb-1
PRL 99, (2007)
Y(4360)
2-BW fit with interference
Absence of open charm production
is inconsistent with conventional charmonium
Galina Pakhlova

7. Y states vs inclusive cross section e+e–→hadrons
(3770)
if Ruds=2.285±0.03
Durham Data Base
Y(4008)
(4040)
(4160)
Y(4260)
Y(4325)
(4415)
Y(4660)
Peak positions for M(J/) & M((2S)) significantly different
Y(4008) mass is close to (4040)
Y(4260) mass corresponds to dip in inclusive cross section
Galina Pakhlova

8. Interpretations of Y states
Problem:
No room for Y states among conventional 1– – charmonium
quark model S.Godfrey and N.Isgur PRD32,189 (1985)
33S1= (4040), 23D1 = (4160), 43S1 = (4415) are measured
masses of predicted 33D1 (4520), 53S1 (4760), 43D1(4810) higher(lower) Y masses
Options
Y(4325) = 33D1 , Y(4660) = 53S1 with shifted masses
G.J Ding et al Phys.Rev.D77: (2008)
A.M.Badalyan et al arXiv:
Charmonium hybrids
Zhu S.L.; Close F.E.; Kou E.and Pene O.
are expected by LQCD in region GeV
the dominant decay Y(4260)→DD1 (threshold 4287 MeV)
Hadro-charmonium
Specific charmonium state “coated” by excited light-hadron matter
S.Dubinskiy, M.B.Voloshin, A.Gorsky
Multiquark states
[cq][cq] tetraquark Maiani L., Riquer V., Piccinini F., Polosa A.D.
DD1 or D*D0 molecules Swanson E.; Rosner J.L., Close F.E.
S-wave charm meson thresholds Lui X.
Galina Pakhlova

9. Charmonium states contribution to inclusive cross section e+e−→ hadrons above open charm threshold
ψ(3770), ψ(4040), ψ(4160), ψ(4415) have been known for more then 25 years
M, Γtot, Γee are quite uncertain
To fix the resonance parameters one needs to know their decay channels to take into account their interference:
How to take into account non-resonant contribution?
How to take into account many open charm thresholds?
Galina Pakhlova

10. Last fit to the inclusive R spectrum
Resonance shapes
Interference term
Rres=RBW+Rint
Phys.Lett.B660,315(2008)
The interference is taken into account
model dependent
Significant effect of interference
To reduce model dependence
need to measure exclusive
cross sections e+e−→D(*)D(*)
BaBar y(3770)DD
Rearrange slide
Galina Pakhlova

11. with full reconstruction
e+e– →DD
via ISR
with full reconstruction D 
s=E2cm-2EEcm e+ e–
reconstructed
not reconstructed
if undetectable
Full reconstruction of hadronic part
ISR photon detection is not required
but used if it is in the detector acceptance
Galina Pakhlova

12. e+e−  DD at s~3.7−5 GeV via ISR
D0D0 or D+D– (full reconstruction)
no extra tracks
detection of γISR is not required
if γISR is detected
M(DDγISR) is required ~ Emc
670 fb-1
D+D–
D0D0
Phys.Rev.D77,011103(2008)
Combinatorial bgs are estimated from D sb
Other bgs are small and taken into account
γISR is not detected
Consistent with ISR production DD
γISR is detected
Galina Pakhlova

13. e+e–  D(*)D(*)cross section calculation
Translate measured mass spectra to cross sections:
D(*)D(*)
Measured D(*)D(*) mass spectra
Total efficiency
Differential ISR luminosity
Galina Pakhlova

14. σ(ee→D+D−)/σ(ee →D0D0) = 0.72±0.16±0.06
(4040)
(4160)
(4415)
670 fb-1
(3770)
σ(e+e− →DD)
σ(ee→D+D−)/σ(ee →D0D0) = 0.72±0.16±0.06
at MDD≈M(3770)
is consistent with BES&CLEOc
Broad structure around 3.9 GeV is in qualitative agreement ?? with coupled-channel model Phys. Rev. D21, 203 (1980)
Some structure between (4040) and (4160)
Statistics is small
Hint of (4415)
Galina Pakhlova

15. σ(e+e− →DD) Durham Data Base Phys.Rev.D77,011103(2008)
arXiv:
Durham Data Base
Galina Pakhlova

16. with partial reconstruction
e+e– →D(*)D*
via ISR
with partial reconstruction
D(*) D 
s=E2cm-2EEcm e+ e– π
reconstructed
not reconstructed
but constrained D*
DD* & D*D*
D* partial reconstruction
increase eff ~ times
detection of ISR photon
Galina Pakhlova

17. e+e–→D(*)D* with partial reconstruction
Reconstruction of D(*) γISR
wide peak in Mrec(D(*)γISR) at M D*
contribution from e+e–→D(*)D* (n)πγ
Reconstruction of D(*) γISR + πslow from unreconstructed D*
wide peak in Mrec(D(*)π-γISR) at MD
Use recoil mass difference
Mrec = Mrec(D(*)γISR) - Mrec(D(*)πγISR)
narrow peak at (MD* - MD)
cancellation of momentum smearing
Tight ΔMrec cut small background
Use kinematical constraint Mrecoil(D(*)γISR) →MD* to improve resolution
Phys. Rev. Lett. 98, (2007)
D*+D*-
D+ D*-
Mrec(D*+γISR)
ΔMrec
MD*
MD*
with ΔMrec cut
σRMD~1 MeV
Galina Pakhlova

18. Exclusive e+e–→D(*)D* cross-sections
(4160)
(4040)
arXiv:
D*+D*-
D+D*-
550/fb
(4040)
(4415)
Phys. Rev. Lett. 98, (2007)
(4160)
Y(4260)
Backgrounds are reliably
estimated from the data
Y(4260) signal
DD* : hint, but not significant
D*D* : clear dip (similar to inclusive R)
Systematic errors ≈ statistical errors
Durham Data Base
Galina Pakhlova

19. Three body final states
s=E2cm-2EEcm e+ e– π
reconstructed
not reconstructed
if undetectable
D0 D− +
full reconstruction of hadronic part
ISR photon detection is not required
but used if it is in the detector acceptance
Galina Pakhlova

20. e+e−  D0D–+ at s ~ 4−5 GeV via ISR
Consistent with ISR production
670 fb-1
D0 D− π+
full reconstruction
no extra tracks
similar analysis and bgs
no major bgs except for combinatorial
Clear (4415)DD signal
Galina Pakhlova

21. Resonant structure in (4415)DD
M(D0π+) vs M(D–π+) from (4415) region
Clear D*2(2460) signals
Constructive interference
No non-D*2(2460) contribution
DDπ non DD*2(2460)
DD*2(2460)
~10σ
670 fb-1
Phys.Rev.Lett.100,062001(2008)
M = 4411± 7 MeV
Γtot =77±20 MeV
Nev= 109± 25
Consistent with BES,
Phys.Lett.B660,315(2008)
PDG06, Barnes at.al
Phys. Rev. D72, (2005)
σ(e+e–→(4415))×Br((4415)→DD*2(2460))×Br(D*2(2460) →Dπ)=(0.74±0.17±0.07)nb
Br((4415)  D(D)non D2(2460))/Br((4415) DD*2(2460))<0.22
Galina Pakhlova

22. Charm baryons final states
Partial reconstruction with anti-proton tag
Λc+ X 
s=E2cm-2EEcm e+ e– p
reconstructed
not reconstructed
Λc– ─
p tag ─
Reconstruct Λc+
anti-proton tag from inclusive Λc–→p–X Br(Λc+→pX) = (50±16)%
combinatorial background
suppressed by a factor of 10
detect the high energy ISR photon
Galina Pakhlova

23. partial reconstruction with p tag
Λc sidebands
Mrecoil(Λc+γISR)
Λc–
Λc–(2595)
Λc–(2625)
Λc–(2765)
Λc–(2880)
no Σ–
partial reconstruction with p tag ─
e+e–→Λc+Λc– γISR
Clear peak in Mrec(Λc+ISR )
distribution at Λc mass.
Wide shoulder for mass >2.5GeV/c2
contributions from Λc+Λc–π0
could proceed via Λc+Σ– ; violates isospin and should be highly suppressed
and Λc+Λc–π π
could proceed via Λc+Λc(2595)–, Λc+Λc(2625)–, Λc+Λc(2765)–, Λc+Λc(2880)–
Apply asymmetric requirement on Mrec(Λc+ISR ) to suppress tail from Λc+Λc–π0 and Λc+Λc–π π reflection
Total refection contributions < 5% (included in systematics)
Use kinematical constraint Mrecoil(ΛcISR)  M Λc to improve resolution
Look at Mrecoil(ISR) ≡ Mass spectra of Λc+Λc–
Galina Pakhlova

24. no peak-like structure
670 fb-1
X(4630)
8.2
Phys.Rev.Lett.101,172001(2008)
e+e–→Λc+Λc– γISR
NEW
e+e–→Λc+Λc– γISR
no peak-like structure
dibaryon threshold effect
like in B→pΛπ, J/→γpp
Interpretations for the new X(4630)
X(4630) = Y(4660)? JPC=1––
53S1 charmonium state
in some models M (53S1) ~4670MeV
Something else...
Galina Pakhlova

25. Contribution to the inclusive cross section
D*D*
DD* DD
DDπ
Λc+Λc–
Contribution to the inclusive cross section
Galina Pakhlova

26. Belle: Sum of all measured exclusive contributions
D*D*
DD*
(4040)
(4160)
Y(4008)
(4415)
Y(4660)
Y(4260)
Y(4360) DD
DDπ
Λc+Λc– ?
PRD77,011103(2008)
PRL100,062001(2008)
σ(e+e–→open charm) via ISR
NEW
PRL98, (2007)
Phys.Rev.Lett.101,172001(2008)
(3770)
if Ruds=2.285±0.03
Durham Data Base
Y(4008)
(4040)
(4160)
Y(4260)
Y(4360)
(4415)
Y(4660)
Belle: Sum of all measured exclusive contributions
Y states vs exclusive cross sections
Y(4008) mass coincides with DD* peak
Y(4260) mass corresponds to dip in D*D* X-sect.
Y(4660) mass is close to Λc+Λc– peak
Enhancement near 3.9 GeV in ee→DD coupled channel effect?
(4415) more contributions to be measure
Galina Pakhlova

27. In conclusion Five exclusive open charm final states were measured
DD, DDπ, D*D, D*D*, ΛcΛc
Their sum is close to e+e– → hadrons
Belle & BaBar &Cleo_c cross sections measurements are consistent with each other in corresponding energy ranges
D*D* (main contribution)
complicated shape of cross section
clear dip at M(D*D*) ~ 4260GeV (similar to inclusive R)
DD* (main contribution)
broad peak at threshold (shifted relative to 4040 GeV) DD
broad enhancement ~ 3.9 GeV – coupled channel effect?
DDπ
(4415) signal observed, dominated by (4415)→DD2 (2460)
ΛcΛc
Enhancement at threshold, mass and width are consistent with Y(4660)
Galina Pakhlova

28. All presented cross sections could be found in Durham Data Base
In conclusion
Theoretical efforts
to describe charm components
of R are kindly requested!
Galina Pakhlova

29. To do list
Galina Pakhlova