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arXiv 1102.4748hep-ex
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用DELPHI探测器在LEP I研究b夸克碎裂函数和在Z极得到的平均分布

A study of the b-quark fragmentation function with the DELPHI detector at LEP I and an averaged distribution obtained at the Z Pole

DELPHI Collaboration, J. Abdallah

摘要:

利用LEP的DELPHI探测器在Z峰处获得的数据研究了b夸克喷注强子化的性质。用两种互补的方法重建了弱衰变b强子的能量E^weak_B。X^weak_B = E^weak_B/E_beam的平均值被测量为0.699 +/-0.011。然后在微扰贡献的两种选择(部分子簇射和Next to Leading Log QCD计算)的框架下分析得到的x^weak_B分布,以便提取非微扰贡献的测量值,用于LEP以外的其他实验环境中b-强子产生的研究。在部分子簇射框架中,数据支持Lund模型的解释,并由DELPHI数据在PYTHIA~6.156范围内确定了相应的参数值:a= 1.84^{+0.23}_{-0.21}和b=0.642^{+0.073}_{-0.063} GeV^-2,相关因子rho = 92.2%。将b夸克碎裂分布的数据与ALEPH、OPAL和SLD在Z峰处得到的数据相结合,得到x^weak_B的平均值为0.7092 ± 0.0025,并提取了非微扰碎裂分量。利用组合分布,还得到了更好的Lund参数:a= 1.48^{+0.11}_{-0.10}和b=0.509^{+0.024}_{-0.023} GeV^-2,相关因子rho = 92.6%。

英文摘要:

The nature of b-quark jet hadronisation has been investigated using data taken at the Z peak by the DELPHI detector at LEP. Two complementary methods are used to reconstruct the energy of weakly decaying b-hadrons, E^weak_B. The average value of x^weak_B = E^weak_B/E_beam is measured to be 0.699 +/- 0.011. The resulting x^weak_B distribution is then analysed in the framework of two choices for the perturbative contribution (parton shower and Next to Leading Log QCD calculation) in order to extract measurements of the non-perturbative contribution to be used in studies of b-hadron production in other experimental environments than LEP. In the parton shower framework, data favour the Lund model ansatz and corresponding values of its parameters have been determined within PYTHIA~6.156 from DELPHI data: a= 1.84^{+0.23}_{-0.21} and b=0.642^{+0.073}_{-0.063} GeV^-2, with a correlation factor rho = 92.2%. Combining the data on the b-quark fragmentation distributions with those obtained at the Z peak by ALEPH, OPAL and SLD, the average value of x^weak_B is found to be 0.7092 +/- 0.0025 and the non-perturbative fragmentation component is extracted. Using the combined distribution, a better determination of the Lund parameters is also obtained: a= 1.48^{+0.11}_{-0.10} and b=0.509^{+0.024}_{-0.023} GeV^-2, with a correlation factor rho = 92.6%.

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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