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arXiv 1602.05322hep-ph
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考虑强子和底夸克质量影响的极化顶夸克衰变中的强子能谱

Hadron energy spectrum in polarized top quark decays considering the effects of hadron and bottom quark masses

S. Mohammad Moosavi Nejad, Mahboobe Balali

摘要:

在固定味数方案(FFNs)下,给出了非零b夸克质量($m_b\neq 0$)的部分衰变宽度($t(\uparrow) \rightarrow bW^+$,随后是$b\rightarrow H_bX$)的次领先阶修正的解析表达式.为了预测出射强子$H_b$的能量分布,我们在一个特定的螺旋度坐标系中应用广义质量变味数方案(GM-VFN),计算顶夸克相对于b夸克动量的极化率,作为归一化$H_b$能量分数$x_H$的函数.我们还研究了胶子碎裂和有限强子质量对强子能谱的影响,使得强子质量是低$x_H$阈值的原因。为了描述顶衰变中的b夸克和胶子强子化,我们利用普适性和标度违反,将通过全局拟合提取的真实的非微扰碎裂函数应用于CERN LEP1和SLAC SLC的$e^+e^-$湮灭数据.

英文摘要:

We present the analytical expressions for the next-to-leading order corrections to the partial decay width $t(\uparrow) \rightarrow bW^+$, followed by $b\rightarrow H_bX$, for nonzero b-quark mass ($m_b\neq 0$) in the fixed-flavor-number scheme (FFNs). To make the predictions for the energy distribution of outgoing hadrons $H_b$, as a function of the normalized $H_b$-energy fraction $x_H$, we apply the general-mass variable-flavor-number scheme (GM-VFNs) in a specific helicity coordinate system where the polarization of top quark is evaluated relative to the b-quark momentum. We also study the effects of gluon fragmentation and finite hadron mass on the hadron energy spectrum so that hadron masses are responsible for the low-$x_H$ threshold. In order to describe both the b-quark and the gluon hadronizations in top decays we apply realistic and nonperturbative fragmentation functions extracted through a global fit to $e^+e^-$ annihilation data from CERN LEP1 and SLAC SLC by relying on their universality and scaling violations.

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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