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arXiv 0802.2563nucl-thhep-phnucl-ex
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介子云与核子电磁形状因子

Meson Clouds and Nucleon Electromagnetic Form Factors

Gerald A. Miller

摘要:

与常见的非相对论知识相比,通常的萨克斯形状因子不是电荷或磁化强度密度的傅立叶变换。相反,电磁$F_1$形状因子的二维傅里叶变换是横平面中部分子的电荷密度。对中子形状因子的可用数据的分析导致的结果是,中子电荷密度在中心处为负,并且横向电荷半径的平方为正。这与许多人的期望相反。另外,使用测量的质子形状因子导致质子的中心$u$夸克电荷密度比$d$夸克的电荷密度大约80%的结果。质子(中子)电荷密度具有长范围的带正(负)电荷的分量,表明存在π介子云。

英文摘要:

In contrast with common non-relativistic lore, the usual Sachs form factors are not the Fourier transforms of charge or magnetization densities. Instead, the two-dimensional Fourier transform of the electromagnetic $F_1$ form factor is the charge charge density of partons in the transverse plane. An analysis of the available data for neutron form factors leads to the result that the neutron charge density is negative at the center, and that the square of the transverse charge radius is positive. This contrasts with many expectations. Additionally, the use of measured proton form factors leads to the result that the proton's central $u$ quark charge density is larger than that of the $d$ quark by about 80%. The proton (neutron) charge density has a long range positively (negatively) charged component indicative of a pion cloud.

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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