论文标题
解密接近阈值$ j/ψ$光增生的机制
Deciphering the mechanism of near-threshold $J/ψ$ photoproduction
论文作者
论文摘要
据信，质子的$ j/ψ$的光生源可加深我们对各种物理问题的理解。一方面，建议基于QCD多极扩展，可以提供对质子质量原点的访问。另一方面，它可以用于对五夸克州的研究。通常认为该过程是通过向量 - 梅森优势进行的，即$ j/ψ$的光子夫妇与质子脱离质子，以提供$ j/ψp$最终状态。在这封信中，我们提供了一个引人入胜的提示，并提出了通过$λ_C\ bar d^{（*）} $中间状态确认新生产机制所需的测量。特别是，必须在$λ_C\ bar d^{（*）} $阈值的$ J/ψ$光增生性横截面的能量依赖性中有尖端结构。相同的机制也意味着$ j/ψ$ -Nucleon散射长度为1 mfm。鉴于此，人们期望魅力夸克对核子质量的贡献很小。
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.
