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Register a new userAnalyzing B_s - bar B_s mixing: Non-perturbative contributions to bag parameters from sum rules
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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 subleading operators R_2 and R_3, which appear at next-to-leading order in the 1/m_b expansion. We conclude that the violation of the factorization approximation for these matrix elements due to non-perturbative vacuum condensates is as low as 1-2%.
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The form factors and the coupling constant of the $B_s B^* K $ and $B_s B K^*$ vertices are calculated using the QCD sum rules method. Three point correlation functions are computed considering both the heavy and light mesons off-shell in each vertex, from which, after an extrapolation of the QCDSR results at the pole of the off-shell mesons, we obtain the coupling constant of the vertex. The form factors obtained have different behaviors but their simultaneous extrapolation reach the same value of the coupling constant $g_{B_s B^* K}=8.41 pm 1.23 $ and $g_{B_s BK^*}=3.3 pm 0.5$. We compare our result with other theoretical estimates and compute the uncertainties of the method.
In this addendum to $B_s$ mixing observables and $|V_{td}/V_{ts}|$ from sum rules cite{King:2019lal} we study the impact of the recent improvements in the theoretical precision of $B$ meson mixing onto CKM unitarity fits. Our key results are the most precise determination of the angle $gamma = left(63.4pm0.9right)^circ$ in the unitarity triangle and a new value for the CKM element $|V_{cb}|=(41.6pm0.7)cdot10^{-3}$.
We study the effect of unparticle stuff on $B_s - bar{B}_s$ mixing and consider possible implications of it for the decaymodes $B_s to J/psi phi$ and $phi phi$. We find that due to the new contributions from the unparticles the $B_s - bar{B}_s$ mixing phase could be observable at the LHC along with the possible sizable CP asymmetry parameters $S_{psi phi(phi phi)}$ in $B_s to J/psi phi(phi phi)$ decay modes.
The recent observation of the mass difference in $B_s$ system seems to be not in complete agreement with the corresponding standard model value. We consider the model with an extra vector like down quark to explain this discrepancy and obtain the constraints on the new physics parameters. Thereafter, we show that with these new constraints this model can successfully explain other observed deviations associated with $b to s$ transitions, namely, $B_s to psi phi$, $Bto K pi$ and $Bto phi K_s$.
Finite energy QCD sum rules with Legendre polynomial integration kernels are used to determine the heavy meson decay constant $f_{B_c}$, and revisit $f_B$ and $f_{B_s}$. Results exhibit excellent stability in a wide range of values of the integration radius in the complex squared energy plane, and of the order of the Legendre polynomial. Results are $f_{B_c} = 528 pm 19$ MeV, $f_B = 186 pm 14$ MeV, and $f_{B_s} = 222 pm 12$ MeV.
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