We update the theory predictions for the mass difference ∆M s , the width difference ∆Γ s and the CP asymmetry in flavour-specific decays, a s fs , for the B s −B s system. In particular we present a new expression for the element Γ s 12 of the decay matrix, which enters the predictions of ∆Γ s and a s fs. To this end we introduce a new operator basis, which reduces the troublesome sizes of the 1/m b and α s corrections and diminishes the hadronic uncertainty in ∆Γ s /∆M s considerably. Logarithms of the charm quark mass are summed to all orders. We find ∆Γ s /∆M s = (49.7 ± 9.4) • 10 −4 and ∆Γ s = (f Bs /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 Bs. The improved result for Γ s 12 also permits the extraction of the CP-violating B s −B s mixing phase from a s fs with better accuracy. We show how the measurements of ∆M s , ∆Γ s , a s fs , A mix CP (B s → J/ψφ) and other observables can be efficiently combined to constrain new physics. Applying our new formulae to data from the DØ experiment, we find a 2σ deviation of the B s −B s mixing phase from its Standard Model value. We also briefly update the theory predictions for the B d −B d system and find ∆Γ d /∆M d = 52.6 +11.5 −12.8 • 10 −4 and a d fs = −4.8

In the framework of a 2HDM effective lagrangian for the MSSM, we analyse important phenomenological aspects associated with quantum soft SUSY-breaking effects that modify the relation between the bottom mass and the bottom Yukawa coupling. We derive a resummation of the dominant supersymmetric corrections for large values of tanβ to all orders in perturbation theory. With the help of the operator product expansion we also perform the resummation of the leading and next-to-leading logarithms of the standard QCD corrections. We use these resummation procedures to compute the radiative corrections to the t → b H + , H + → tb decay rates. In the large tanβ regime, we derive simple formulae embodying all the dominant contributions to these decay rates and we compute the corresponding branching ratios. We show, as an example, the effect of these new results on determining the region of the M H + -tanβ plane excluded by the Tevatron searches for a supersymmetric charged Higgs boson in top quark decays, as a function of the MSSM parameter space.

No abstract

We compute the QCD corrections to the decay rate difference in the B s -B s system, ∆Γ Bs , in the next-to-leading logarithmic approximation using the heavy quark expansion approach. Going beyond leading order in QCD is essential to obtain a proper matching of the Wilson coefficients to the matrix elements of local operators from lattice gauge theory. The lifetime difference is reduced considerably at next-to-leading order. We find (∆Γ/Γ)063] in terms of the bag parameters B, B S in the NDR scheme. As a further application of our analysis we also derive the next-to-leading order result for the mixing-induced CP asymmetry in inclusive b → uūd decays, which measures sin 2α. [3,4]. In principle, a measured value for ∆Γ Bs could also give some information on the mass difference ∆M Bs [5], if the theoretical prediction for the ratio (∆Γ/∆M) Bs can be sufficiently well controlled [6]. Furthermore, as pointed out in [7], if non-standardmodel sources of CP violation are present in the B s system, ∆Γ Bs can be smaller (but not larger) than expected in the standard model. For this reason a lower bound on the standard model prediction is of special interest.The calculation of inclusive non-leptonic b-hadron decay observables, such as ∆Γ Bs , uses the heavy quark expansion (HQE). The decay width difference is expanded in powers of Λ QCD /m b , each term being multiplied by a series of radiative corrections in α s (m b ). In the case of (∆Γ/Γ) Bs , the leading contribution is parametrically of order 16πIn the framework of the HQE the main ingredients for a reliable prediction (less than 10% uncertainty) are a) subleading corrections in the 1/m b expansion, b) the non-perturbative matrix elements of local four-quark operators between B-meson states and c) O(α s ) radiative corrections to the Wilson coefficients of these operators. The first issue has been addressed in [6]. The hadronic matrix elements can be studied using numerical simulations in lattice QCD. In this letter, we present the next-to-leading order QCD radiative corrections to the Wilson coefficient functions for ∆Γ Bs . In addition to removing another item from the above list and reducing certain renormalization scale ambiguities of the leading order prediction, the inclusion of O(α s ) corrections is necessary for a satisfactory matching of the Wilson coefficients to the matrix elements to be obtained from lattice calculations.Our results provide the first calculation of perturbative QCD effects beyond the leading logarithmic approximation to spectator effects in the HQE for heavy hadron decays. The consideration of subleading QCD radiative effects has implications of conceptual interest for the construction of the HQE. Soft gluon emission from the spectator s quark in the B s meson leads to power-like IR singularities in individual contributions, which would apparently impede the HQE construction, because they cannot be absorbed into matrix elements of local operators. It has already been explained in [8], how these severe IR divergences cancel in the...

The presence of a sizable CP-violating phase in B s -B s mixing would be an unambiguous signal of physics beyond the standard model. We analyze various possibilities to detect such a new phase considering both tagged and untagged decays. The effects of a sizable width difference ⌬⌫ between the B s mass eigenstates, on which the untagged analyses rely, are included in all formulas. A novel method to find this phase from simple measurements of lifetimes and branching ratios in untagged decays is proposed. This method does not involve two-exponential fits, which require much larger statistics. For the tagged decays, an outstanding role is played by the observables of the time-dependent angular distribution of theWe list the formulas needed for the angular analysis in the presence of both a new CP-violating phase and a sizable ⌬⌫, and propose methods to remove a remaining discrete ambiguity in the new phase. This phase can therefore be determined in an unambiguous way.