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arXiv 1305.6464hep-ph
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使用分段函数对\bar{B} -> X_d gamma的树级贡献

Tree-level contribution to \bar{B} -> X_d gamma using fragmentation functions

H. M. Asatrian, C. Greub

摘要:

我们用碎裂函数计算了b-> u \bar{u} d γ跃迁到包含辐射衰变\bar{B} -> X_d γ的最重要的树能级贡献。在这个框架中,由轻夸克(u,\bar{u}和d)的共线光子发射产生的奇异性可以被吸收到(裸)夸克到光子碎裂函数中。作为输入,我们使用的碎裂函数提取的ALEPH组从两个射流截面在LEP测量,其中一个射流需要包含一个光子。为了得到μ_F \sim m_b下的夸克-光子碎裂函数,我们利用演化方程,数值求解。然后,我们计算与算子P^ u_{1,2}相关的b-> u \bar{u} d gamma的(积分)光子能谱。为了比较,我们也给出了相应的结果时,使用非零(组分)质量的轻夸克。

英文摘要:

We evaluate the most important tree-level contributions connected with the b-> u \bar{u} d gamma transition to the inclusive radiative decay \bar{B}-> X_d gamma using fragmentation functions. In this framework the singularities arising from collinear photon emission from the light quarks (u, \bar{u} and d) can be absorbed into the (bare) quark-to-photon fragmentation function. We use as input the fragmentation function extracted by the ALEPH group from the two-jet cross section measured at LEP, where one of the jets is required to contain a photon. To get the quark-to-photon fragmentation function at the fragmentation scale μ_F \sim m_b, we use the evolution equation, which we solve numerically. We then calculate the (integrated) photon energy spectrum for b-> u \bar{u} d gamma related to the operators P^u_{1,2}. For comparison, we also give the corresponding results when using nonzero (constituent) masses for the light quarks.

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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