1 / 11

Possible Mechanism for Understanding the Near Threshold Enhancement in J/ψ → γ pp

Possible Mechanism for Understanding the Near Threshold Enhancement in J/ψ → γ pp. Xiao-Hai Liu Institute of High Energy Physics, CAS. Collaborators: Qiang Zhao, Yuan-Jiang Zhang (Phys. Rev. D 80, 034032, 2009). Near Threshold Enhancement in J/ψ → γ pp (BESII results).

marvin-boyer
Download Presentation

Possible Mechanism for Understanding the Near Threshold Enhancement in J/ψ → γ pp

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Possible Mechanism for Understanding the Near Threshold Enhancement in J/ψ→γpp Xiao-Hai Liu Institute of High Energy Physics, CAS Collaborators: Qiang Zhao, Yuan-Jiang Zhang (Phys. Rev. D 80, 034032, 2009)

  2. Near Threshold Enhancement in J/ψ→γpp(BESII results) M= 1859 MeV Γ< 30 MeV JPC=0-+ χ2/d.o.f.=56.3/56 Phys. Rev. Lett. 91, 022001

  3. Interpretations on this Phenomenon • Glueball candidate (Kochelev & Min; B.A. Li; Hao et al.; … ) • Baryonium (Datta & O’Donnell; Ding & Yan; Loiseau & Wycech; Zhu & Gao; …) • Final states pp interactions (Zou & Chiang; Kerbikov et al.; Bugg; Sibirtsev et al.; Entem & Fernandez; Chen et al.; …)

  4. Motivations of Considering VV Rescatering • The VV invariant mass distribution is dominated by the 0- components in J/ψ→γVV, and most of these channels have relatively larger branching ratios. (PLB 353, 378; PRD 73, 112007; PLB 472, 200; PRD 33, 1222; PRD 39, 701.) A very broad 0- resonance observed by BES, M=1800 MeV • These vector mesons generally have strong couplings with the nucleons and/or hyperons.

  5. The Model Suppressed Free Parameters Insignificant

  6. Numerical Fitting Results Model dependent parameters: • '1.15»1.20 GeV ', ' -/2 Destructive interferences

  7. Cross Section of pp→VV • In the experiments of pp annihilations at rest, i.e. pLab=200 Mev/c2, Crystal Barrel Collaboration, 1993 C. Baltay et al., 1963 • With the same effective Lagrangians, form factors and coupling constants as in J/ψ→γpp, • We didn’t overestimate the contributions of VV → pp

  8. Results for J/ψ→pp We could only do a rough estimation according to BESII result (PRD77, 032005) The corresponding parameters are taken the same as those in J/ψ→pp

  9. How to understand some other channels No significant enhancement BESII, 2007 CLEO, 2005

  10. How to understand some other channels • There is no significant narrow threshold enhancement in these two channels. • The pp FSI which fits the data of J/ψ→γpp will confront problems here, however it needs a more accurate experimental data as a premise. • Because of lack of the data for and some other related channels, our rescattering mechanism still needs to be checked in these processes.

  11. Summary and Outlook • The VV-rescattering effects, i.e. J/ψ→ γVV→γpp , may one of the possible mechanisms which can produce the near threshold enhancement observed by BESII in J/ψ→ γpp . • The fitting result indicates that the enhancement may be resulted from the destructive interference between different rescattering amplitudes. • The forthcoming BESIII results on J/ψ(ψ’)→ γpp and J/ψ(ψ’)→pp may help us to clarify this phenomenon and the underlying mechanism.

More Related