arXiv 2009.083452020-09-17hep-phhep-exhep-latnucl-exnucl-th

近阈值$J/ψ$光产生机制的研究

Deciphering the mechanism of near-threshold $J/ψ$ photoproduction

Meng-Lin Du, Vadim Baru, Feng-Kun Guo, Christoph Hanhart, Ulf-G. Meißner, Alexey Nefediev, Igor Strakovsky

备注：: 6 pages, 5 figures
发表信息：: Eur. Phys. J. C 80 (2020) 1053
DOI：: 10.1140/epjc/s10052-020-08620-5

摘要：

质子光生$J/ψ$被认为加深了我们对各种物理问题的理解。一方面，它建议提供访问的质子质量的起源，基于QCD多极展开。另一方面，它可以用于研究五夸克态。这个过程通常被假设为通过矢量介子主导进行，也就是说，光子耦合到$J/ψ$，$J/ψ$与质子重新散射，得到$J/ψp$最终状态。在这封信中，我们提供了一个令人信服的提示，并提出必要的测量，以确认一种新的生产机制，通过$Λ_c \bar D^{(*)}$中间状态。特别地，在截面的$J/ψ$的能量依赖性中，在$Λ_c \bar D^{(*)}$阈值处必须存在尖点结构。同样的机制也意味着$J/ψ$ -核子散射长度为1毫微分。考虑到这一点，我们可以预期粲夸克对核子质量的贡献很小。

英文摘要：

The photoproduction of the $J/ψ$ off the proton is believed to deepen our understanding of various physics issues. On the one hand, it is proposed to provide access to the origin of the proton mass, based on the QCD multipole expansion. On the other hand, it can be employed in a study of pentaquark states. The process is usually assumed to proceed through vector-meson dominance, that is the photon couples to a $J/ψ$ which rescatters with the proton to give the $J/ψp$ final state. In this Letter, we provide a compelling hint for and propose measurements necessary to confirm a novel production mechanism via the $Λ_c \bar D^{(*)}$ intermediate states. In particular, there must be cusp structures at the $Λ_c \bar D^{(*)}$ thresholds in the energy dependence of the $J/ψ$ photoproduction cross section. The same mechanism also implies the $J/ψ$-nucleon scattering lengths of order 1 mfm. Given this, one expects only a minor contribution of charm quarks to the nucleon mass.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

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