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Discovery of Charmonium-like Meson States via ISR

This study explores the inclusive cross section of e+e- collisions at ~3.7-5 GeV, focusing on open charm final states and the discovery of charmonium-like meson states. The analysis involves both partial and full reconstruction techniques to identify the different final states and their cross sections. The results provide insights into the production and properties of these meson states.

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Discovery of Charmonium-like Meson States via ISR

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  1. e+e−→ open charm via ISRX(4160) in J/ recoil Quarkonium Working Group, October 20, 2007 Galina Pakhlova ITEP for the Belle Collaboration

  2. Experiment Belle “An unexpected bonus from the B-factory experiments has been the discovery of a large number of charmonium-like meson states…” Galina Pakhlova

  3. e+e− open charm final states

  4. PDG 2006 Y(4260) R-study around open charm threshold e+e- machines at s~(3.7 -5) GeV • inclusive e+e- hadrons cross-section • complicated structure • model and fit dependent description For years no exclusive studies e+e- specific final states Last years new interest both in experiment and theory A lot of new data!!! Galina Pakhlova

  5. e- e- e+ s=(Ecm-E)2-p2 D(*) reconstructed D*  D not reconstructed but constrained Exclusive e+e−D(*)D* cross-sections via ISR Method ISR at B-factories comparable with energy scan (CLEOc, BES) • Hard ISR photon takes away significant fraction of energy • Continuous ISR spectrum: access to whole s interval • emsuppression, but ~ 700/fb at Belle vs ~ 60/pb CLEO-c The first measurement Belle: D*+D*-, D+ D*- with partial reconstruction • increase eff ~ 10 − 20 times Galina Pakhlova

  6. Phys. Rev. Lett. 98, 092001 (2007) D+ D*- D*+D*- MD* MD* Mrec(D*+ISR) Mrec(D+ISR) ΔMrec ΔMrec e+e-D(*)D* with partial reconstruction • Full reconstruction D(*) ISR • wide peak inMrec(D(*)ISR)atM D* • contribution from e+e-D(*)D* (n)πγ • Full reconstruction D(*) ISR +slowfrom unreconstructed D* • wide peak inMrec(D(*)-ISR)atMD • Use recoil mass difference ΔMrec = Mrec(D(*)ISR) - Mrec(D(*)ISR) • narrow peak at(MD* - MD) cancellation of momentum smearing • Tight ΔMreccut  small background • Use kinematical constraint Mrecoil(D(*) ISR) MD* to improve resolution with ΔMrec cut RMD~1 MeV Galina Pakhlova

  7. Phys. Rev. Lett. 98, 092001 (2007) D*+D*- CHARM 2007 (4415) D*D* (4160) (4040) (4160) Y(4260) D+D*- PRELIMINARY (4040) DD* Y(4260) 550/fb Exclusive e+e–D(*)D*cross-sections Charged D(*)D* ½ from CLEOc • Systematic errors ≈ statistical errors • Submitted to Durham database Y(4260) signal DD* : hint, but not significant D*D* : clear dip (similar to inclusive R) Galina Pakhlova

  8. D0D0 orD+D–(full reconstruction) • no extra tracks D0D0 DD D+D– 670 fb-1 ISR is not detected • Combinatorial bgs are estimated from D s/b • Other bgs are small and taken into account Consistent with ISR production NEW e+e− DD at s~3.7−5 GeV via ISR • detection of ISRis not required • if ISRis detected M(DD ISR) is required ~ Ecm ISR is detected Galina Pakhlova

  9. arXiv:0708.0082 arXiv:0710.1371 (4160) (4415) (4040) (4040) Y(4260) (4160) (3770) Y(4260) 670 fb-1 (4415) 384 fb-1 Mass spectra of DD no signalY(4260)DD Belle&BaBar are in a qualitative agreement Galina Pakhlova

  10. Charm 2007 DD (4040) (e+e– DD) (4160) (4040) PRELIMINARY (4160) 670 fb-1 (3770) (4415) Phys. Rev. Lett. 98, 092001 (2007) D*D* DD* Broad structure around 3.9 GeV is in qualitative agreement ?? with coupled-channel model Phys.Rev.D21, 203 (1980) Cross section above 4 GeV has a similar shape to this measured for ee  D*D* ? σ(ee  D+D−)/σ(ee  D0D0) = 0.720.160.06 at MDD≈M(3770) is consistent with BES/CLEOc Galina Pakhlova

  11. 670 fb-1 Consistent with ISR production NEW e+e− D0D–+ at s ~ 4−5 GeV via ISR D0 D−+ • full reconstruction • no extra tracks Clear (4415)DD signal • similar analysis and bgs • no major bgs except for combinatorial Galina Pakhlova

  12. arXiv:0708.3313, submitted to PRL 670 fb-1 DD*2(2460) ~10σ M = 4411± 7 MeV tot =77±20 MeV Nev= 109± 25 DD non DD*2(2460) Consistent with BES, hep-ex/0705.4500, PDG06, Barnes at.al Phys. Rev. D72, 054026 (2005) 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 Br((4415)  D(D)non D2(2460))/Br((4415) DD*2(2460))<0.22 σ(e+e-(4415))×Br((4415)DD*2(2460))×Br(D*2(2460) D)=(0.74±0.17±0.07)nb Galina Pakhlova

  13. NEW DD Phys. Rev. Lett. 98, 092001 (2007) arXiv:0708.0082 submitted to PRD(RC) DDπ NEW D*D* DD* arXiv:0708.3313, submitted to PRL Contributions to the inclusive cross-section at 3.7-5GeV + + 2 = 2 uds-continuum Anything else? These 4 final states almost saturate inclusive cross section Galina Pakhlova

  14. New state in double charmonium production

  15. arXiv:0708.3812 D* D*π D 693fb-1 D* D All signals are > 5 New study of e+e− J/ D(*)D(*) • The method is pioneered by Belle • Reconstruct J/ and one of two D (or D*) • Unreconstructed D(*) is seen as a peak Mrecoil (J/ D(*)) • D and D* recoiling against reconstructed J/ D(*)are well separated (~2.5) • Simultaneous fit toD-signal and D-sidebands to fix bg Phys. Rev. Lett. 98, 082001 (2007) Galina Pakhlova

  16. e+e–J/DD DD 3.8 D • Tag unreconstructedD: • |Mrecoil (J/ D) - MD| < 70MeV • Refit Mrecoil (J/ D) MD : • improve M DD by ~10 • Broad peak at MDDis not consistent with non resonant • DDproduction in the process • e+e− J/ DD • large fitting systematic error in the parameters of this enhancement Galina Pakhlova

  17. e+e– J/DD*andD*D X(3940) D reconstructedD*tag ee J/ DD reflection D*-reconstructedD-tag 6.0  M = 3942 ±6 MeV tot =37 ±12 MeV Nev= 52 ±11 +7 -6 3.8 +26 - 15 X(3940) cross check +24 - 16 D* D • X(3940)DD* confirmed with new data • M and  are in agreement with published results. Galina Pakhlova

  18. M=(4156 15)MeV/c2  =(139 21)MeV +25 −20 D*reconstructed D*tag +111 −61 X(4160) 5.5 e+e− J/ D*D* D* Broad clear peak at threshold • New state X(4160) ≠ψ(4160)is observed in D*D* decay mode One more particle to explain … JPС=0−+(hc (4S)) is not excluded Galina Pakhlova

  19. Summary

  20. e+e−open charm D*D* • complicated shape of cross section • consistent with CLEO_c at MD*D* (3.8-4.3) GeV • clear dip at MD*D* ~ 4260GeV (similar to inclusive R) DD* • broad peak at threshold (shifted relative to 4040 GeV) • consistent with CLEO_c at MDD* (3.8-4.3) GeV • hint at MDD* ~ 4260GeV DD • complicated shape of cross section • consistent with CLEO_c at MDD (4.0-4.3) GeV • σ(ee(3770)→DD) consistent with BES/CLEO_c • broad enhancement ~ 3.9 GeV – coupled channel effect? • above 4GeV similar shape as D*D* DD • (4415) signal observed, dominated by (4415)  DD**2 • DD + DD + D*D + D*D* cross section is close to ee  hadrons( - ee  uds continuum) Galina Pakhlova

  21. Double charmonium production X(3940) • is confirmed with a significance ~ 6.0 X(4160) • NEW state observed for the first time ~ 5.5  Galina Pakhlova

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