Related papers: QSSR estimate of the $B_B$ parameter at next-to-le…
The accuracy of the vacuum saturation hypothesis is discussed using the examples of vacuum expectation values of four-quark operators and the parameter $B$, which determines the short-distance contribution to the $K^0 - \bar K^0$ mixing.…
In this talk, I present new results [1] obtained from QCD spectral sum rules (QSSR), on the bag constant parameters entering in the analysis of the B^0_{(s)}-\bar B^0_{(s)} mass-differences. Taking the average of the results from the…
We use QCD sum rules to compute matrix elements of the Delta B=2 operators appearing in the heavy-quark expansion of the width difference of the B_s mass eigenstates. Our analysis includes the leading-order operators Q and Q_S, as well as…
The QCD finite energy sum rules method is used to show that the parameter of the K^0-\bar{K}_0 mixing \hat{B} is mainly determined by the value of g m_s< \bar{d} G_{\mu\nu} \sigma_{\mu\nu} d > and the vacuum expectation values of four-quark…
We present the preliminary result of the calculation of $B_B$ parameter using lattice NRQCD. The calculation is performed on a $16^3 \times 48$ quenched lattice at $\beta=5.9$ with clover light quark. The use of lattice NRQCD enables us to…
We extract the matrix elements of four quark operators O_{L,S} relevant to the B_s and \bar B_s life time difference from QCD sum rules. We find the vacuum saturation approximation works reasonably well, i.e., within 10%. We discuss the…
We compute the perturbative corrections to the HQET sum rules for the matrix element of the \Delta B=2 operator that determines the mass shift of $B^0$, $\bar{B}^0$ states. Technically, we obtain analytically the non-factorizable…
We present our results of lattice calculations of $B$ parameters, which parameterize $\Delta B$=2 transition amplitudes together with the leptonic decay constant. Calculations are made in the quenched approximation at $\beta$=5.7, 5.9, 6.0…
We present our recent results for the B-parameters, which parameterize the \Delta B=2 transition amplitudes. Calculations are made in quenched QCD at \beta=5.7, 5.9, and 6.1, using NRQCD for heavy quark and the $O(a)$-improved action for…
We report on the calculation of next-to-next-to-leading order (NNLO) QCD corrections to the width difference $\Delta \Gamma_s$ in the neutral $B$-meson mixing process $B^0_s - \bar{B}^0_s$. These contributions represent an important step in…
The matrix element of B^0 -\bar B^0 mixing is evaluated from QCD sum rules for three-point correlators with next-to-leading order accuracy in pQCD.
We present a calculation of the B0 - anti-B0 mixing matrix element in the framework of QCD sum rules for three-point functions. We compute alpha_s corrections to a three-point function at the three-loop level in QCD perturbation theory,…
We calculate the next-to-leading order QCD corrections to $B$ to scalar meson form factors from QCD light-cone sum rules with $B$ meson light-cone distribution amplitudes. We demonstrate that the $B$ meson-to-vacuum correlation functions…
The QED vacuum polarization function is calculated to O(alpha^2) (next-to-leading order) accuracy in the threshold regime by using the concept of effective field theories to resum diagrams with the instantaneous Coulomb exchange of…
We present results of a large-scale simulation for the Kaon B parameter $B_K$ in quenched lattice QCD with the Kogut-Susskind quark action. Calculating $B_K$ at 1% statistical accuracy for seven values of lattice spacing in the range…
In this talk I report on the results of a recent calculation of the \alpha_s corrections to a three-point correlation function at the three-loop level in QCD perturbation theory, which allows one to extract the matrix element of B^0 -\bar…
We extend the theoretical prediction for the width difference $\Delta \Gamma_q$ in the mixing of neutral $B$ mesons in the Standard Model to next-to-next-to-leading order in $\alpha_s$. To this aim we calculate three-loop diagrams with two…
Combining our results for various O(alpha_s^2) corrections to the weak radiative B-meson decay, we are able to present the first estimate of the branching ratio at the next-to-next-to-leading order in QCD. We find BR(B -> X_s gamma) = (3.15…
The decay constants of the pseudoscalar mesons B and B_s are evaluated from QCD sum rules for the pseudoscalar two-point function. Recently calculated perturbative three-loop QCD corrections are incorporated into the sum rule. An analysis…
We calculate the QCD corrected effective Hamiltonian for $B\bbar$--Mixing in heavy quark effective theory including corrections of the order $\Lambda_{QCD} / m_b$. The matrix elements of the subleading operators are estimated using the…