Phi-meson photo-production to study multi-gluon exchange process

菲介子照片制作研究多胶子交换过程

• 批准号: 14340075
• 负责人: NAKANO Takashi
• 金额: $ 8.83万
• 依托单位: Osaka University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2002
• 资助国家: 日本
• 起止时间: 2002 至 2003
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14340075/
• 关键词: Phi-meson; Pomeron; Laser-Electron Photon; Theta particle; 光生成; グルーオン; グルーボール

Since a $phi$ meson is almost pure s s_bar state, diffractive photo-production for a Ф meson off a proton in a wide energy range is well described as a pomeron-exchange (multi gluon-exchange) process in the framework of the Regge theory and of the Vector Dominance Model ; a high energy photon converts into a Ф meson and then it is scattered from a proton by an exchange of the pomeron while the meson-exchange is suppressed by the OZI rule. However, at low energies other contributions arising from meson (π, η)-exchange, a scaler (0^<++>glueball)-exchange, and ss_bar knock-out are possible. These contributions fall off rapidly as the incident photon energy increases, and can be studied only in the low energy region near the production threshold. Linearly polarized photons are an ideal probe to decompose these contributions. For natural-parity exchange such as pomeron and 0^<++>glueball exchanges, the decay plane of $K^+K^-$ is concentrated in the photon polarization vector. For unnatural-parity exchange processes like π and ηexchange processes, it is perpendicular to the polarization vector. A preliminary analysis of the KK decay asymmetry for Φphoto-productions in the forward angles showed the natural-parity exchange contributions are still dominant. The cross-section shows a bump structure near 2 GeV which cannot be explained by Pomeron exchange contribution only. Thus we conclude there must be additional natural-parity exchange contribution, which may be attributed to a new Regge trajectory associated with 0^<++> glueball. As a bi-product of this study, we found evidence for a narrow S=+1 baryon resonance in photo-production from a neutron, which may be interpreted as a Pentaquark state Θ^+.

由于A $ PHI $ MESON几乎是纯S_bar状态，因此在较宽的能量范围内，在质子范围内，在质子范围内，质子脱离质子的衍射照片产生是Pomeron-Exchange（多gluton-Exchange）在Regge理论和矢量优势模型的框架中的Pomeron-exthange（Multi Gluton-Exchange）过程；高能量照片转换为hemon，然后通过波梅隆的交换将其从质子散射，而介子交换被OZI规则抑制。然而，在低能下，可能可能由介子（π，η）-Exchange，缩放器（0^<++>粘合球）-exchange和ss_bar敲除产生其他贡献。随着入射光子能量的增加，这些贡献迅速下降，并且只能在生产阈值附近的低能区域进行研究。线性极化照片是分解这些贡献的理想探针。对于诸如Pomeron和0^<++>粘合球交换之类的自然交换，$ K^+K^ - $的衰减平面集中在光子极化向量上。对于诸如π和ηExchange过程之类的不自然交换过程，它垂直于极化载体。对向前角度的φPhoto产生的KK衰减不对称的初步分析表明自然差异的贡献仍然是主导的。横截面显示了2 GEV附近的凸起结构，仅由Pomeron交换贡献来解释。我们包含的必须有其他自然交换贡献，这可能归因于与0^<++>粘合球相关的新regge轨迹。作为这项研究的培养基，我们发现了来自中子的照片产生中狭窄的S =+1 baryon共振的证据，中子可以解释为pentaquark状态θ^+。

项目成果

Evidence for Narrow S=+1 Baryon Resonance in Photo-production from Neutron

中子照片制作中窄 S= 1 重子共振的证据

• 发表时间: 2003
• 期刊: Physical Review Letters 91
• 作者: T.Nakano;et al.
• 通讯作者: et al.