Galina Pakhlova ITEP&Belle

International Workshop on Heavy Quarkonia 20082-5 December 2008, Nara Women's University

Galina Pakhlova2

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

R(s) = σ(e+e–→hadrons, s)/ σ(e+e–→μ+μ–, s)

Galina Pakhlova3

Y(4260)

Y(4325)Y(4660)

Y(4008)

Curious 1– – family

Galina Pakhlova4

e+e−→ 1– – final states via ISR

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

c

c

e-

s=E2cm-2EEcm

e+

e–

e+

1– –

Galina Pakhlova5

PRL 99, 182004 (2007)

550 fb-1

2-BW fit with interference • two solutions: different peak cross sections

Y(4008)7.4σ Y(4260)

PRL 99, 182004 (2007)

550 fb-1

2-BW fit with interference • two solutions: different peak cross sections

Y(4008)7.4σ Y(4260)

Two or one states in e+e–→J/π+π– γISR ?Y(4260)

454 fb-1

344±39 ev

Y(4008)

arXiv:0808.1543

NEW

Absence of open charm production is inconsistent with conventional

charmonium

< 0.7 90% CL

7.5±0.9±0.8

Br(J/π+π–)Γee , eV

Solution1 Y(4008) Solution2

Solution1 Y(4260) Solution2

(2S)First Y(4260)PRL 95,142001(2005)

233 fb-1

8σ

(2S)First Y(4260)PRL 95,142001(2005)

233 fb-1

8σ

Confirmed PRL 96,162003(2006)

+ J/00 (5.1σ)

11σConfirmed PRL 96,162003(2006)

+ J/00 (5.1σ)

11σPRD74,091104R(2006)

13.3 fb-15.4σ

PRD74,091104R(2006)

13.3 fb-15.4σ

Galina Pakhlova6

Y(4360)→(2S)ππ

PRL 98, 212001 (2007)

298 fb-1

Y(4660) ?

e+e–→(2S) π+π– γISR

Y(4360), Y(4660) ...

2-BW fit with interference

Absence of open charm production is inconsistent with conventional charmonium

Y(4360) 8σ

Y(4660) 5.8

670 fb-1

PRL 99, 142002 (2007)

Y(4360)

Y(4360)

Galina Pakhlova7

Y states vs inclusive cross section e+e–→hadrons

Peak positions for M(J/) & M((2S)) significantly differentY(4008) mass is close to (4040)Y(4260) mass corresponds to dip in inclusive cross section

(3

770)

if Ruds=2.285±0.03 Durham Data Base

Y(4

008)

(4

040)

(4

160)

Y(4

260)

Y(4

325)

(441

5)

Y(4

660)

Galina Pakhlova8

Interpretations of Y states Problem:

No room for Y states among conventional 1– – charmoniumquark 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

OptionsY(4325) = 33D1 , Y(4660) = 53S1 with shifted masses

G.J Ding et al Phys.Rev.D77:014033 (2008) A.M.Badalyan et al arXiv:0805.2291

Charmonium hybrids Zhu S.L.; Close F.E.; Kou E.and Pene O.

• are expected by LQCD in region 4.2-5 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.GorskyMultiquark 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 Pakhlova9

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 Pakhlova10

Resonance shapes Interference term

Rres=RBW+Rint

Phys.Lett.B660,315(2008)

Last fit to the inclusive R spectrum

To reduce model dependence need to measure exclusive cross sections e+e−→D(*)D(*)

The interference is taken into account • model dependent

Significant effect of interference

Galina Pakhlova11

D

D

s=E2cm-2EEcm

e+

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

e+e– →DD via ISR

with full reconstruction

Galina Pakhlova12

Combinatorial bgs are estimated from D sb Other bgs are small and taken into account

γISR is not detected

Consistent with ISR production

DD

e+e− DD at s~3.7−5 GeV via ISR

γISR is detected

670 fb-1

D+D–

D0D0

Phys.Rev.D77,011103(2008)

• D0D0 or D+D– (full reconstruction)

• no extra tracks

• detection of γISR is not required

• if γISR is detected

• M(DDγISR) is required ~ Emc

Galina Pakhlova13

e+e– D(*)D(*)cross section calculation

Measured D(*)D(*) mass spectra

Differential ISR luminosityTotal efficiency

Translate measured mass spectra to cross sections:

D(*)D(*)

Galina Pakhlova14

σ(ee→D+D−)/σ(ee →D0D0) = 0.72±0.16±0.06

at MDD≈M(3770) is consistent with BES&CLEOc

(4040)

(4160)

(4415)

670 fb-1(3770)

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)

σ(e+e− →DD)

Galina Pakhlova15

Phys.Rev. D76, 111105(2007)

σ(e+e− →DD)

Phys.Rev.D77,011103(2008)

arXiv:0801.3418

Durham Data Base

Galina Pakhlova16

D(*)

D

s=E2cm-2EEcm

e+

e–

e+

π

reconstructed

not reconstructed

but constrained

D*

DD* & D*D*

D* partial reconstruction • increase eff ~ 10-20 times

detection of ISR photon

e+e– →D(*)D* via ISR

with partial reconstruction

Galina Pakhlova17

e+e–→D(*)D* with partial reconstructionPhys. Rev. Lett. 98, 092001 (2007)

D*+D*- D+ D*-

Mrec(D*+γISR) Mrec(D*+γISR)

ΔMrecΔMrec

MD*

with ΔMrec cut

σRMD~1 MeV

MD*

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

Galina Pakhlova18

D*+D*-

D+D*-

550/fb

(4040)

(4415)

Phys. Rev. Lett. 98, 092001 (2007)

(4160)

Y(4260)

Exclusive e+e–→D(*)D* cross-sections

Y(4260) signal DD* : hint, but not significant D*D* : clear dip (similar to inclusive R) • Systematic errors ≈ statistical errors

(4160)

(4040)

arXiv:0801.3418

(4160)

(4040)

Durham Data Base

Backgrounds are reliably estimated from the data

Galina Pakhlova19

D

D

s=E2cm-2EEcm

e+

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

Three body final states

Galina Pakhlova20

e+e− D0D–+ at s ~ 4−5 GeV via ISR

D0 D− π+ full reconstruction no extra tracks

Clear (4415)DD signal

similar analysis and bgs no major bgs except for combinatorial

Consistent with ISR production

670 fb-1

Galina Pakhlova21

Resonant structure in (4415)DD

Br((4415) D(D)non D2(2460))/Br((4415) DD*2(2460))<0.22

M = 4411± 7 MeVΓtot =77±20 MeV

Nev= 109± 25

Consistent with BES,Phys.Lett.B660,315(2008)

PDG06, Barnes at.al Phys. Rev. D72, 054026 (2005)

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)

σ(e+e–→(4415))×Br((4415)→DD*2(2460))×Br(D*

2(2460) →Dπ)=(0.74±0.17±0.07)nb

Galina Pakhlova22

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

Λc+

X

s=E2cm-2EEcm

e+

e–

e+

p

reconstructed

not reconstructed

Λc–

─

Partial reconstruction with anti-proton tag Charm baryons final states

p tag ─

Galina Pakhlova23

e+e–→Λc+Λc

– γISR

Λ c sidebands

Mrecoil(Λc+γISR)

Λc–

Λc–(2595)

Λc–(2625)

Λc–(2765)

Λc–(2880)

no Σ–

partial reconstruction with p tag ─

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(ΛcISR) M Λc to improve resolution Look at Mrecoil(ISR) ≡ Mass spectra of Λc

+Λc–

Galina Pakhlova24

670 fb-1

X(4630) 8.2

Phys.Rev.Lett.101,172001(2008)

e+e–→Λc+Λc

– γISR

NEW

e+e–→Λc+Λc

– γISR

PRL 99,142002(2007)

ee→ΛΛ via ISR

PRD73,012005(2006)

ee→pp via ISR

PRL 99,142002(2007)

ee→ΛΛ via ISR

PRD73,012005(2006)

ee→pp via ISR

• no peak-like structure

PRL 97, 242001 (2006)

6.2σ B–→Λc+p π–─

PRL 97, 242001 (2006)

6.2σ B–→Λc+p π–─

• dibaryon threshold effect • like in B→pΛπ, J/→γpp

Interpretations for the new X(4630)

•53S1 charmonium state • in some models M (53S1) ~4670MeV

• Something else...

• X(4630) = Y(4660)? JPC=1––

Galina Pakhlova25

Contribution to the inclusive cross section

D*D*

DDπ

DD*

DD

Λc+Λc

–

Galina Pakhlova26

D*D*

DD*

(4

040)

(4

160)

Y(4

008)

(4

415)

Y(4

660)

Y(4

260)

Y(4

360)

DD

DDπ

Λc+Λc

–

?

PRD77,011103(2008)

PRL100,062001(2008)

σ(e+e–→open charm) via ISR

NEW

PRL98, 092001 (2007)

Phys.Rev.Lett.101,172001(2008)

(3

770)

if Ruds=2.285±0.03

Durham Data Base

Y(4

008)

(4

040)

(4

160)

Y(4

260)

Y(4

360)

(4

415)

Y(4

660)

Belle: Sum of all measured exclusive contributions

Y states vs exclusive cross sectionsY(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

– peakEnhancement near 3.9 GeV in ee→DD coupled channel effect?

(4415) more contributions to be measure

Galina Pakhlova27

In conclusionFive 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 • complicated shape of cross section • 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 Pakhlova28

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 Pakhlova29

To do list