Electromagnetic dipole operator effect on B{yields}X{sub s}{gamma} at O({alpha}{sub s}{sup 2})
- Department of Physics, University of Alberta, Edmonton, AB T6G 2J1 (Canada)
- Institute of Theoretical Physics, Warsaw University, 00-681 Warsaw (Poland)
- Institute for Nuclear Research, Russian Academy of Sciences, Moscow, 117312 (Russian Federation)
The flavor-changing electromagnetic dipole operator O{sub 7} gives the dominant contribution to the B{yields}X{sub s}{gamma} decay rate. We calculate two-loop QCD corrections to its matrix element together with the corresponding bremsstrahlung contributions. The optical theorem is applied, and the relevant imaginary parts of three-loop diagrams are computed following the lines of our recent t{yields}X{sub b}W calculation. The complete result allows us to test the validity of the naive non-Abelianization (NNA) approximation that has been previously applied to estimate the next-to-next-to-leading order QCD correction to {gamma}(B{yields}X{sub s}{gamma})/{gamma}(B{yields}X{sub u}e{nu}). When both decay widths are normalized to m{sub b,R}{sup 5} in the same renormalization scheme R, the calculated O({alpha}{sub s}{sup 2}) correction is sizable ({approx}6%), and the NNA estimate is about 1/3 too large. On the other hand, when the ratio of the decay widths is written as Sxm{sub b,MS}{sup 2}(m{sub b})/m{sub b,pole}{sup 2}, the calculated O({alpha}{sub s}{sup 2}) correction to S is at the level of 1% for both the complete and the NNA results.
- OSTI ID:
- 20711204
- Journal Information:
- Physical Review. D, Particles Fields, Vol. 72, Issue 3; Other Information: DOI: 10.1103/PhysRevD.72.033014; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2821
- Country of Publication:
- United States
- Language:
- English
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