Revisiting the bottom quark forward-backward asymmetry AFB in electron-positron collisions
Revisiting the bottom quark forward-backward asymmetry AFB in electron-positron collisions
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重新审视正负电子碰撞中的底夸克前后不对称 AFB
DOI：
10.1140/epjc/s10052-020-8234-x
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Shen Jian-Ming
中科院分区：
文献类型：
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作者：
Wang Sheng-Quan;Meng Rui-Qing;Wu Xing-Gang;Chen Long;Shen Jian-Ming
底夸克前后不对称性AFB是正负电子碰撞中在Z 0峰处观察到的一个关键现象。在本文中，我们采用最大保形性原理（PMC）来固定次领先阶QCD修正对AFB的α s运行行为。由此产生的PMC规模为该AFB是一个数量级小于传统的选择μ r=MZ。该标度具有物理上合理的行为，反映了QCD动力学的虚拟性，与重整化标度的选择无关。我们的分析表明，底夸克前后不对称的有效动量流应该是μ r << MZ，而不是通常所认为的μ r=MZ.此外，使用PMC大大改善了AFB微扰QCD级数的收敛性。我们对裸底夸克前后不对称性的预测被修正为AFB 0，B=0.1004 +/- 0.0016，这减少了这个（伪）观测值的实验测定与相应的标准模型拟合到2.1 σ之间的众所周知的张力。
The bottom quark forward-backward asymmetry AFB is a key observable in electron-positron collisions at the Z0 peak. In this paper, we employ the Principle of Maximum Conformality (PMC) to fix the alpha s-running behavior of the next-to-next-to-leading order QCD corrections to AFB. The resulting PMC scale for this AFB is an order of magnitude smaller than the conventional choice mu r=MZ. This scale has the physically reasonable behavior and reflects the virtuality of its QCD dynamics, which is independent to the choice of renormalization scale. Our analyses show that the effective momentum flow for the bottom quark forward-backward asymmetry should be mu r << MZ other than the conventionally suggested mu r=MZ. Moreover, the convergence of perturbative QCD series for AFB is greatly improved using the PMC. Our prediction for the bare bottom quark forward-backward asymmetry is refined to be AFB0,b=0.1004 +/- 0.0016, which diminishes the well known tension between the experimental determination for this (pseudo) observable and the respective Standard Model fit to 2.1 sigma.