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arXiv 0707.0650hep-ph
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QCD和SUSY QCD中b夸克的运行质量

Running mass of the b-quark in QCD and SUSY QCD

A. V. Bednyakov

摘要:

在超对称量子色动力学(SUSY QCD)中,DRbar方案中定义的b夸克的运行质量是一个重要参数。为了找到它的值,它应该与一些已知的实验输入有关。本文选用非超对称QCD中定义的b夸克运行质量来确定超对称QCD中相应的参数。这两个量之间的关系是通过考虑五味QCD作为一个有效的理论,从它的超对称扩展。计算的双环关系及其对MSSM频谱的影响的数值分析进行了讨论。由于非超对称模型的MSbar计划是更自然的比DRbar,我们还提出了一个新的程序,允许一个计算MSbar和DRbar参数之间的关系。非物理的ε-标量,引起上述计划之间的差异被假定为是沉重的和解耦的物理自由度相同的方式。通过这种方法,可以“抓住两只兔子”,即,重粒子解耦,同时从DRbar变为MSbar。在QCD背景下给出了DRbar -> MSbar跃迁的两圈例子。简要讨论了该方法的优点和缺点。

英文摘要:

The running mass of the b-quark defined in DRbar-scheme is one of the important parameters of SUSY QCD. To find its value it should be related to some known experimental input. In this paper the b-quark running mass defined in nonsupersymmetric QCD is chosen for determination of corresponding parameter in SUSY QCD. The relation between these two quantities is found by considering five-flavor QCD as an effective theory obtained from its supersymmetric extension. A numerical analysis of the calculated two-loop relation and its impact on the MSSM spectrum is discussed. Since for nonsupersymmetric models MSbar-scheme is more natural than DRbar, we also propose a new procedure that allows one to calculate relations between MSbar- and DRbar-parameters. Unphysical epsilon-scalars that give rise to the difference between mentioned schemes are assumed to be heavy and decoupled in the same way as physical degrees of freedom. By means of this method it is possible to ``catch two rabbits'', i.e., decouple heavy particles and turn from DRbar to MSbar, at the same time. Explicit two-loop example of DRbar -> MSbar transition is given in the context of QCD. The advantages and disadvantages of the method are briefly discussed.

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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