## Abstract

We compute the virtual (α_{s}^{2}) fermionic contributions to the charm quark mass dependent matrix elements of the X _{s}γ decay. In the case of a massless quark loop insertion into the gluon propagator, our result obtained as an expansion in z ≤ m _{c}^{2}/m_{b}^{2} and an exact expression in terms of multi-fold MB integrals, confirms the findings of Bieri, Greub and Steinhauser [22]. In the case of a b-quark loop insertion, we observe large differences between the actual massive case and the massless approximation. These turn out, as expected, to be less pronounced for the charm quark.

Original language | English (US) |
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Article number | 072 |

Journal | Journal of High Energy Physics |

Volume | 2007 |

Issue number | 9 |

DOIs | |

State | Published - Sep 1 2007 |

## Keywords

- B-physics
- QCD
- Rare decays

## ASJC Scopus subject areas

- Nuclear and High Energy Physics

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