Complete NNLO QCD Analysis of B -> 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 ab...
| Main Authors: | , , , |
|---|---|
| Format: | Journal article |
| Published: |
2003
|
| _version_ | 1826288962728099840 |
|---|---|
| author | Bobeth, C Gambino, P Gorbahn, M Haisch, U |
| author_facet | Bobeth, C Gambino, P Gorbahn, M Haisch, U |
| author_sort | Bobeth, C |
| collection | OXFORD |
| 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 +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. |
| first_indexed | 2024-03-07T02:21:39Z |
| format | Journal article |
| id | oxford-uuid:a41f9d30-e6b7-4062-90e0-c33dc20bd6cb |
| institution | University of Oxford |
| last_indexed | 2024-03-07T02:21:39Z |
| publishDate | 2003 |
| record_format | dspace |
| spelling | oxford-uuid:a41f9d30-e6b7-4062-90e0-c33dc20bd6cb2022-03-27T02:31:43ZComplete NNLO QCD Analysis of B -> X_s l^+ l^- and Higher Order Electroweak EffectsJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:a41f9d30-e6b7-4062-90e0-c33dc20bd6cbSymplectic Elements at Oxford2003Bobeth, CGambino, PGorbahn, MHaisch, UWe 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. |
| spellingShingle | Bobeth, C Gambino, P Gorbahn, M Haisch, U Complete NNLO QCD Analysis of B -> X_s l^+ l^- and Higher Order Electroweak Effects |
| title | Complete NNLO QCD Analysis of B -> X_s l^+ l^- and Higher Order
Electroweak Effects |
| title_full | Complete NNLO QCD Analysis of B -> X_s l^+ l^- and Higher Order
Electroweak Effects |
| title_fullStr | Complete NNLO QCD Analysis of B -> X_s l^+ l^- and Higher Order
Electroweak Effects |
| title_full_unstemmed | Complete NNLO QCD Analysis of B -> X_s l^+ l^- and Higher Order
Electroweak Effects |
| title_short | Complete NNLO QCD Analysis of B -> X_s l^+ l^- and Higher Order
Electroweak Effects |
| title_sort | complete nnlo qcd analysis of b gt x s l l and higher order electroweak effects |
| work_keys_str_mv | AT bobethc completennloqcdanalysisofbgtxsllandhigherorderelectroweakeffects AT gambinop completennloqcdanalysisofbgtxsllandhigherorderelectroweakeffects AT gorbahnm completennloqcdanalysisofbgtxsllandhigherorderelectroweakeffects AT haischu completennloqcdanalysisofbgtxsllandhigherorderelectroweakeffects |