Two-loop QCD corrections to {ital b}{bold {r_arrow}}{ital c} transitions at zero recoil
- Institut fuer Theoretische Teilchenphysik, Universitaet Karlsruhe, D-76128 Karlsruhe (Germany)
Complete two-loop QCD corrections to {ital b}{r_arrow}{ital c} transitions are presented in the limit of zero recoil. Vector and axial-vector coefficients {eta}{sub {ital A},{ital V}} are calculated analytically in the limit of equal beauty and charm masses, and a series appoximation is obtained for the general mass case. {eta}{sub {ital A}} is crucial for the determination of the absolute value of the Cabibbo-Kobayashi-Maskawa matrix element {ital V}{sub {ital cb}}. The two-loop effects enhance the one-loop corrections by 22{percent}, removing a major theoretical uncertainty in the value of {vert_bar}{ital V}{sub {ital cb}}{vert_bar}. Including two-loop QCD effects and previously neglected electroweak corrections we find {vert_bar}{ital V}{sub {ital cb}}{vert_bar}=0.0383{plus_minus}0.0021(stat){plus_minus}0.0025(syst){plus_minus}0.0011(theory). {copyright} {ital 1996 The American Physical Society.}
- OSTI ID:
- 288887
- Journal Information:
- Physical Review Letters, Journal Name: Physical Review Letters Journal Issue: 22 Vol. 76; ISSN 0031-9007; ISSN PRLTAO
- Country of Publication:
- United States
- Language:
- English
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