Institut für Theoretische Teilchenphysik
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Institute for Theoretical Particle Physics (TTP)
Institute for Theoretical Particle Physics (TTP)
Institute for Theoretical Particle Physics (TTP)
Preprints
2006
TTP06-31 Theoretical update of Bs--Bs-bar mixing
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 +====== TTP06-31 Theoretical update of Bs--Bs-bar mixing ====== 
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 +   <hidden TTP06-31  Theoretical update of Bs--Bs-bar mixing > We update the theory predictions for the mass difference Delta m_s, the 
 + width difference Delta Gamma_s and the CP asymmetry in flavour-specific 
 + decays, a_fs^s, for the Bs-Bs-bar mixing system. In particular we 
 + present a new expression for the element Gamma_{12}^s of the decay 
 + matrix, which enters the predictions of Delta Gamma_s and a_fs^s.  To 
 + this end we introduce a new operator basis, which reduces the 
 + troublesome sizes of the 1/m_b and alpha_s corrections and diminishes 
 + the hadronic uncertainty in Delta Gamma_s/Delta m_s considerably. 
 + Logarithms of the charm quark mass are summed to all orders.  We find 
 + Delta m_s = (49.7 =/- 9.4 ) * 10^{-4} and Delta Gamma_s =(f_{B_s}/240 
 + MeV)^2 [(0.105 +/- 0.016) B + (0.024 +/- 0.004) B_S~' - 0.027 +/- 0.015] 
 + ps^{-1} in terms of the bag parameters B, B_S~' in the NDR scheme and 
 + the decay constant f_{B_s}. The improved result for Gamma_{12}^s also 
 + permits the extraction of the CP-violating Bs-Bs-bar mixing phase from 
 + a_fs^s with better accuracy.  We show how the measurements of Delta M_s, 
 + Delta Gamma_s, a_fs^s, A_CP^mix(B_s\to J/\psi \phi) and other 
 + observables can be efficiently combined to constrain new 
 + physics. Applying our new formulae to data from the D0 experiment, we 
 + find a 2-sigma deviation of the Bs-Bs-bar mixing phase from its Standard 
 + Model value. We also briefly update the theory predictions for the 
 + Bd-Bd-bar mixing system and find Delta Gamma_d/Delta m_d = 
 + (52.6+11.5/-12.8) * 10^{-4} and a_fs^d =(-4.8 +1.0/-1.2}) *10^{-4} in 
 + the Standard Model. 
 + </hidden> 
 +|**Alexander Lenz and Ulrich Nierste**  |  
 +|**  JHEP   0706 072 2007  **  | 
 +| {{preprints:2006:ttp06-31.pdf|PDF}} {{preprints:2006:ttp06-31.ps|PostScript}} [[http://arxiv.org/abs/hep-ph/0612167|arXiv]]   | 
 +| |