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横向电荷密度和质子半径

Transverse charge density and the radius of the proton

Alexander V. Gramolin, Rebecca L. Russell

备注：
Our Python analysis code is available at https://github.com/gramolin/radius/
发表信息：
Phys. Rev. D 105, 054004 (2022)
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摘要：

一个令人费解的差异之间存在的值的质子电荷半径使用不同的实验技术：弹性电子-质子散射和光谱的电子和μ子氢。质子半径是通过在零四动量转移下的电形状因子$G_E(Q^2)$的斜率来定义的，这在散射实验中是无法实现的。我们提出了一种新的方法提取质子半径的散射数据在一个广泛的$Q^2$范围内，而不是试图直接确定$G_E$在$Q^2 = 0$的斜率。该方法将质子的半径与其横向电荷密度相关联，该横向电荷密度是狄拉克形状因子$F_1(Q^2)$的二维傅里叶变换。我们应用我们的方法来重新分析A1合作[J.C. Bernauer等人，物理修订版信函105，242001（2010）]并提取与原始结果一致的半径值$r_E = 0.889(5)_{\text{stat}}(5)_{\text{syst}}(4)_{\text{model}}~\text{fm}$。我们还提供了新的参数化的狄拉克和泡利形状因子和质子的横向电荷和磁化强度密度。我们的再分析表明，质子半径的差异不能解释的问题与拟合和外推的A1数据$Q^2 = 0$。

英文摘要：

A puzzling discrepancy exists between the values of the proton charge radius obtained using different experimental techniques: elastic electron-proton scattering and spectroscopy of electronic and muonic hydrogen. The proton radius is defined through the slope of the electric form factor, $G_E(Q^2)$, at zero four-momentum transfer, which is inaccessible in scattering experiments. We propose a novel method for extracting the proton radius from scattering data over a broad $Q^2$ range rather than attempting to directly determine the slope of $G_E$ at $Q^2 = 0$. This method relates the radius of the proton to its transverse charge density, which is the two-dimensional Fourier transform of the Dirac form factor, $F_1(Q^2)$. We apply our method to reanalyze the extensive data obtained by the A1 Collaboration [J. C. Bernauer et al., Phys. Rev. Lett. 105, 242001 (2010)] and extract a radius value, $r_E = 0.889(5)_{\text{stat}}(5)_{\text{syst}}(4)_{\text{model}}~\text{fm}$, that is consistent with the original result. We also provide new parametrizations for the Dirac and Pauli form factors and the transverse charge and magnetization densities of the proton. Our reanalysis shows that the proton radius discrepancy cannot be explained by issues with fitting and extrapolating the A1 data to $Q^2 = 0$.

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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