Complete NNLO QCD Analysis of $\overline{B} \to X_{s} l^{+} l^{-}$ and Higher Order Electroweak Effects

We complete the next-to-next-to-leading-order QCD calculation of the branching ratio for B -> X_s l^+ l^- including recent results for the three-loop anomalous dimension matrix and two-loop matrix elements. These new contributions modify the branching ratio in the low-q^2 region, BR_ll, by about...

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Detalles Bibliográficos
Autores principales: Bobeth, Christoph, Gambino, Paolo, Gorbahn, Martin, Haisch, Ulrich
Lenguaje:eng
Publicado: 2003
Materias:
Particle Physics - Phenomenology
Acceso en línea:https://dx.doi.org/10.1088/1126-6708/2004/04/071
http://cds.cern.ch/record/690283
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author Bobeth, Christoph
Gambino, Paolo
Gorbahn, Martin
Haisch, Ulrich
author_facet Bobeth, Christoph
Gambino, Paolo
Gorbahn, Martin
Haisch, Ulrich
author_sort Bobeth, Christoph
collection CERN
description We complete the next-to-next-to-leading-order QCD calculation of the branching ratio for B -> X_s l^+ l^- including recent results for the three-loop anomalous dimension matrix and two-loop matrix elements. These new contributions modify the branching ratio in the low-q^2 region, BR_ll, by about +2% and -2%, respectively. We furthermore discuss the appropriate normalization of the electromagnetic coupling alpha, and calculate the dominant higher order electroweak effects, showing that they affect BR_ll and the zero of the forward-backward asymmetry, q^2_0, by -5% to +3%, depending on the normalization scale adopted for alpha(mu_em). After introducing a few additional improvements in order to reduce the theoretical error, we perform a comprehensive study of the uncertainty. We obtain BR_ll(1 GeV^2 <= q^2 <= 6 GeV^2) = (1.702 +- 0.170) x 10^-6 and q^2_0 = (3.23 +- 0.12) GeV^2.
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institution Organización Europea para la Investigación Nuclear
language eng
publishDate 2003
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spelling cern-6902832023-01-31T10:07:10Zdoi:10.1088/1126-6708/2004/04/071http://cds.cern.ch/record/690283engBobeth, ChristophGambino, PaoloGorbahn, MartinHaisch, UlrichComplete NNLO QCD Analysis of $\overline{B} \to X_{s} l^{+} l^{-}$ and Higher Order Electroweak EffectsParticle Physics - PhenomenologyWe complete the next-to-next-to-leading-order QCD calculation of the branching ratio for B -> X_s l^+ l^- including recent results for the three-loop anomalous dimension matrix and two-loop matrix elements. These new contributions modify the branching ratio in the low-q^2 region, BR_ll, by about +2% and -2%, respectively. We furthermore discuss the appropriate normalization of the electromagnetic coupling alpha, and calculate the dominant higher order electroweak effects, showing that they affect BR_ll and the zero of the forward-backward asymmetry, q^2_0, by -5% to +3%, depending on the normalization scale adopted for alpha(mu_em). After introducing a few additional improvements in order to reduce the theoretical error, we perform a comprehensive study of the uncertainty. We obtain BR_ll(1 GeV^2 <= q^2 <= 6 GeV^2) = (1.702 +- 0.170) x 10^-6 and q^2_0 = (3.23 +- 0.12) GeV^2.We complete the next-to-next-to-leading order QCD calculation of the branching ratio for B -> X_s l^+ l^- including recent results for the three-loop anomalous dimension matrix and two-loop matrix elements. These new contributions modify the branching ratio in the low-q^2 region, BR_ll, by about +1% and -4%, respectively. We furthermore discuss the appropriate normalization of the electromagnetic coupling alpha and calculate the dominant higher order electroweak effects, showing that, due to accidental cancellations, they change BR_ll by only -1.5% if alpha(mu) is normalized at mu = O(m_b), while they shift it by about -8.5% if one uses a high scale normalization mu = O(M_W). The position of the zero of the forward-backward asymmetry, q_0^2, is changed by around +2%. After introducing a few additional improvements in order to reduce the theoretical error, we perform a comprehensive study of the uncertainty. We obtain BR_ll(1 GeV^2 <= q^2 <= 6 GeV^2) = (1.57 +- 0.16) x 10^-6 and q_0^2 = (3.76 +- 0.33) GeV^2 and note that the part of the uncertainty due to the b-quark mass can be easily reduced.hep-ph/0312090CERN-TH-2003-260TUM-HEP-532-03FERMILAB-PUB-03-046-TUCSD-PTH-03-19IPPP-03-77CERN-TH-2003-260TUM-HEP-532FERMILAB-PUB-2003-046-TUCSD-PTH-2003-19IPPP-2003-77oai:cds.cern.ch:6902832003-12-05
spellingShingle Particle Physics - Phenomenology
Bobeth, Christoph
Gambino, Paolo
Gorbahn, Martin
Haisch, Ulrich
Complete NNLO QCD Analysis of $\overline{B} \to X_{s} l^{+} l^{-}$ and Higher Order Electroweak Effects
title Complete NNLO QCD Analysis of $\overline{B} \to X_{s} l^{+} l^{-}$ and Higher Order Electroweak Effects
title_full Complete NNLO QCD Analysis of $\overline{B} \to X_{s} l^{+} l^{-}$ and Higher Order Electroweak Effects
title_fullStr Complete NNLO QCD Analysis of $\overline{B} \to X_{s} l^{+} l^{-}$ and Higher Order Electroweak Effects
title_full_unstemmed Complete NNLO QCD Analysis of $\overline{B} \to X_{s} l^{+} l^{-}$ and Higher Order Electroweak Effects
title_short Complete NNLO QCD Analysis of $\overline{B} \to X_{s} l^{+} l^{-}$ and Higher Order Electroweak Effects
title_sort complete nnlo qcd analysis of $\overline{b} \to x_{s} l^{+} l^{-}$ and higher order electroweak effects
topic Particle Physics - Phenomenology
url https://dx.doi.org/10.1088/1126-6708/2004/04/071
http://cds.cern.ch/record/690283
work_keys_str_mv AT bobethchristoph completennloqcdanalysisofoverlinebtoxsllandhigherorderelectroweakeffects
AT gambinopaolo completennloqcdanalysisofoverlinebtoxsllandhigherorderelectroweakeffects
AT gorbahnmartin completennloqcdanalysisofoverlinebtoxsllandhigherorderelectroweakeffects
AT haischulrich completennloqcdanalysisofoverlinebtoxsllandhigherorderelectroweakeffects

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