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arXiv 1601.02787hep-ph
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一种新的色散形式对核子虚康普顿散射的约束

Constraints on the virtual Compton scattering on the nucleon in a new dispersive formalism

Irinel Caprini

备注：
13 pages, 5 figures. Minor changes, additional references, title slightly changed, matches the version published in PRD
发表信息：
Phys. Rev. D 93, 076002 (2016)
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摘要：

虚拟康普顿前向散射振幅的色散表示最近已重新审查与评估的Cottingham公式的质子-中子电磁质量差。分析中最困难的部分与不变振幅之一有关，表示为$T_1(ν, Q^2)$，这需要在标准色散关系中减去固定光子动量平方$q^2=-Q^2$时的能量$ν$。我们提出了一个替代的色散框架，它实现了解析性和幺正性相结合的柯西积分关系在低和中等的能量与模量表示的振幅在高能量。利用泛函分析的技巧，我们导出了减函数$S_1(Q^2)=T_1(0, Q^2)$、中低能电子-质子截面和高能Regge模型与解析性一致的充要条件.从这个条件下，我们得到的减法函数模型无关的约束，面对他们的核子磁极化率和最近在文献中报道的结果的可用信息。该形式也可用于测试角动量平面中$J=0$上固定极点的存在性，但需要更准确的数据才能得到明确的答案。

英文摘要：

The dispersive representation of the virtual Compton forward scattering amplitude has been recently reexamined in connection with the evaluation of the Cottingham formula for the proton-neutron electromagnetic mass difference. The most difficult part of the analysis is related to one of the invariant amplitudes, denoted as $T_1(ν, Q^2)$, which requires a subtraction in the standard dispersion relation with respect to the energy $ν$ at fixed photon momentum squared $q^2=-Q^2$. We propose an alternative dispersive framework, which implements analyticity and unitarity by combining the Cauchy integral relation at low and moderate energies with the modulus representation of the amplitude at high energies. Using techniques of functional analysis, we derive a necessary and sufficient condition for the consistency with analyticity of the subtraction function $S_1(Q^2)=T_1(0, Q^2)$, the electron-proton cross sections measured at low and moderate energies and the Regge model assumed to be valid at high energies. From this condition we obtain model-independent constraints on the subtraction function, confronting them with the available information on nucleon magnetic polarizabilities and results reported recently in the literature. The formalism can be used also for testing the existence of a fixed pole at $J=0$ in the angular momentum plane, but more accurate data are necessary for a definite answer.

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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