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

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

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

e+e−→ 1– – final states via ISR c 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

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 Two or one states in e+e–→J/π+π– γISR ? < 0.7 90% 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

e+e–→(2S) π+π– γISR Y(4360), Y(4660) ... Y(4360)→(2S)ππ PRL 98, 212001 (2007) 298 fb-1 Y(4660) ? Y(4360) 8σ Y(4660) 5.8 670 fb-1 PRL 99, 142002 (2007) Y(4360) 2-BW fit with interference Absence of open charm production is inconsistent with conventional charmonium Galina Pakhlova

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

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.D77:014033 (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.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

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

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

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

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

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

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

σ(e+e− →DD) Durham Data Base Phys.Rev.D77,011103(2008) arXiv:0801.3418 Durham Data Base Galina Pakhlova

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 ~ 10-20 times detection of ISR photon Galina Pakhlova

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, 092001 (2007) D*+D*- D+ D*- Mrec(D*+γISR) ΔMrec MD* MD* with ΔMrec cut σRMD~1 MeV Galina Pakhlova

Exclusive e+e–→D(*)D* cross-sections (4160) (4040) arXiv:0801.3418 D*+D*- D+D*- 550/fb (4040) (4415) Phys. Rev. Lett. 98, 092001 (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

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

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

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, 054026 (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

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

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

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

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

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, 092001 (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

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

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

To do list Galina Pakhlova