e+e−→ J/ D(*)D(*) & ψ(4160) → DD P. Pakhlov (ITEP) for the Belle Collaboration BES-Belle-Cleo-BaBar Meeting, November 25, 2007
Introduction Charmonium above open charm threshold decaying to open charm are seen in ee annihhilation (via ISR at B-factories or energy scan at charm factories) ee double charmonium production X(3940) DD* (4415) ??? DD* More here? one state is found in γγ (4040) D*D* (4160) c2’ DD 02/04/2019 P. Pakhlov
New study of e+e− J/ D(*)D(*) Monte Carlo The method is pioneered by Belle Phys. Rev. Lett. 98, 082001 (2007) Reconstruct J/ and one of two D (or D*) Unreconstructed D(*) is seen as a peak Mrecoil (J/ D(*)) M ~ 30MeV < MD* – MD D and D* recoiling against reconstructed J/ D(*) are well separated (~2.5) e+e− J/ DD(*) with J/ D reconstruction Cross talk e+e− J/ DD to e+e− J/ DD* ~ 15% due to ISR J/ψ D e- D* D e+ M(Dπ) ~ MD* if MDD* is around the threshold 02/04/2019 P. Pakhlov
e+e− J/ D(*)D(*) signals in the data 693fb-1 D* D*π D arXiv:0708.3812 Signals for all three processes are well seen in the data e+e− J/ DD* and e+e− J/ D*D* are seen with both D and D* reconstruction Backgrounds are combinatorial Simultaneous fit to D-signal and D-sidebands to fix bg Monte Carlo: All signals are > 5 02/04/2019 P. Pakhlov
e+e– J/D D D D 3.8 D Tag unreconstructed D: |Mrecoil (J/ D) - M D | < 70MeV Refit Mrecoil (J/ D) M D : improve M DD resolution by ~10 Broad threhsold enhancement at MDD is not consistent with non resonant DD production in the process e+e− J/ DD However: large fitting systematic error in the parameters of this enhancement Significance is still low No definite conclusion! but this study is needed to fix cross talk to e+e− J/ DD* 02/04/2019 P. Pakhlov
D*-reconstructed D-tag e+e– J/DD* and D*D D* X(3940) D reconstructed D*tag 6.0 ee J/ DD reflection D M = 3942 ±6 MeV tot =37 ±12 MeV N = 52 ±11 +7 –6 +26 –15 D*-reconstructed D-tag X(3940) cross check 3.8 +24 –16 X(3940)DD* confirmed with new data M and are in agreement with published results. 02/04/2019 P. Pakhlov
D*reconstructed D*tag e+e− J/ D* D* 5.5 X(4160) D*reconstructed D*tag D* M=(4156 15)MeV/c2 =(139 21)MeV Broad clear peak at threshold New state X(4160)(C=+1) ≠ ψ(4160)(C=–1) is observed in D*D* decay mode +25 −20 +111 −61 One more state to explain … JPС=0− + (c (4S)) is not excluded Born cross-sections for two observed states comparable to other double charmonium cross-sections 02/04/2019 P. Pakhlov
Systematics & cross checks Systematics in masses and widths are dominated by fitting uncertainty (BW and bg parameterizations) Production systematics is dominated by uncertainty in due to unknown angular distributions Cross checks: with different D sb windows with different D subsamples for X(3940)/X(4160) with D and D* reconstructions give consistent results 02/04/2019 P. Pakhlov
e+e− D0D–+ at s ~ 4−5 GeV via ISR Phys. Rev. Lett. 98, 092001 (2007): D*D + D*D* Different reconstruction methods used for different hadronic final states: DD* & D*D* – partial reconstruction of D* + detection of ISR photon DD & D0 D− + – full reconstruction of hadronic part; ISR photon detection is not required (but used if in the detector acceptance) e- e- reconstructed D(*) e+ s=(Ecm-E)2-p2 D* D not reconstructed but constrained arXiv:0708.0082: DD not reconstructed if undetectable e- e- D e+ s=(Ecm-E)2-p2 reconstructed D 02/04/2019 P. Pakhlov
e+e− D0D–+ at s ~ 4−5 GeV via ISR Consistent with ISR production 670 fb-1 D0 D− + full reconstruction no extra tracks similar analysis and bgs to e+e− DD no major bgs except for combinatorial Clear (4415)DD signal 02/04/2019 P. Pakhlov
Resonant structure in (4415)DD M(D0+) vs M(D-+) from (4415) region Clear D*2(2460) signals Positive interference Non D*2(2460) contribution is not seen DD non DD*2(2460) DD*2(2460) ~10σ 670 fb-1 arXiv:0708.3313, accepted by PRL M = 4411± 7 MeV tot =77±20 MeV Nev= 109± 25 Consistent with BES, hep-ex/0705.4500, PDG06, Barnes et.al Phys. Rev. D72, 054026 (2005) σ(e+e-(4415))×Br((4415)DD*2(2460))×Br(D*2(2460) D)=(0.74±0.17±0.07)nb Br((4415) D(D)non D2(2460))/Br((4415) DD*2(2460))<0.22 02/04/2019 P. Pakhlov
Decomposition of inclusive cross-section D*D* DD* Phys. Rev. Lett. 98, 092001 (2007) DD NEW arXiv:0708.0082 submitted to PRD(RC) 2 + + DDπ NEW arXiv:0708.3313, submitted to PRL = 2 uds-continuum Anything else? These 4 final states almost saturate inclusive cross section 02/04/2019 P. Pakhlov
is confirmed with a significance ~ 6.0 X(4160) Summary X(3940) is confirmed with a significance ~ 6.0 X(4160) NEW state observed for the first time ~ 5.5 (4415) (4415) DDπ signal observed, dominated by (4415) DD**2 DD + DD + D*D + D*D* cross section is close to ee hadrons ( ee uds continuum); still a room for (4415) open charm final states exists! 02/04/2019 P. Pakhlov