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arXiv 0908.2746hep-ph
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半包含e^+e^-湮没的高阶阈值重算

Higher-order threshold resummation for semi-inclusive e^+e^- annihilation

S. Moch, A. Vogt

摘要:

在无质量微扰QCD中,导出了三阶半包含e^+e^-湮灭中夸克系数函数的完全软增强和虚胶子贡献。这些项使我们能够将碎裂函数的软胶子重算扩展两个数量级,达到次-首对数(N^3LL)精度。的重混指数被发现是相同的结构功能,包括深非弹性散射。这一发现,连同已知的结果高阶夸克形状因子,有利于确定所有软和虚拟的贡献的四阶差分系数函数为这两个过程。与之前的(N^2LL)次幂不同,在LEP能量下,N^3LL贡献的数值效应可以忽略不计。

英文摘要:

The complete soft-enhanced and virtual-gluon contributions are derived for the quark coefficient functions in semi-inclusive e^+e^- annihilation to the third order in massless perturbative QCD. These terms enable us to extend the soft-gluon resummation for the fragmentation functions by two orders to the next-to-next-to-next-to-leading logarithmic (N^3LL) accuracy. The resummation exponent is found to be the same as for the structure functions in inclusive deep-inelastic scattering. This finding, together with known results on the higher-order quark form factor, facilitates the determination of all soft and virtual contributions of the fourth-order difference of the coefficient functions for these two processes. Unlike the previous (N^2LL) order in the exponentiation, the numerical effect of the N^3LL contributions turns out to be negligible at LEP energies.

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