15654773
Probe new physics in leptonic Bc decays at CERN LHC
With respect to large samples of B-c mesons expected to be produced at CERN Large Hadron Collider (LHC) and the large branching ratios Br(B-c --> tau ) and Br(B-c --> mu ), we suggest that, purely leptonic decays could offer an unique probe of the standard model and its extensions such as two Higgs doublet models and models involving supersymmetry, and also the structure of charged weak currents. (C) 1997 Published by Elsevier Science B.V.
18729265
Semiinclusive decay B ---> phi X(s): Rate and momentum spectrum of phi
We study the rate and $\phi$ momentum distribution in semi-inclusive decays $B \to\phi X_s $ induced by the quark level processes $b\to\phi s$ and $b\to\phi s g$, in which the gluon is radiated from the internal charm quark loop or emitted from the virtual gluon of the strong penguin (inner bremsstrahlung). We find ${\cal B}(b\to\phi s)=6.7\times 10^{-5}$ and ${\cal B}(b\to\phi s g)=3.8\times 10^{-5}$. The momentum spectrum of $\phi$ produced by $b\to\phi s g $ is very broad. With the cut $|{\bf k}_{\phi}|\geq 2.0$ GeV, ${\cal B}(b\to\phi s)=6.1\times 10^{-5}$ (where the Fermi motion of the $b$-quark in the $B$-meson is described by a Gaussian), and ${\cal B}(b\to\phi s g)=1.0\times 10^{-5}$. Due to the special nature of $\phi$, many difficulties which hindered a reliable theoretical prediction for $B\to \eta' X_s$ decay are absent in the process $B\to \phi X_s$. Therefore, theoretical predictions for $B\to \phi X_s$ are relatively clean. Moreover, the clear experimental signature of the $\phi$ is of great help. Data for $B\to\phi X_s$, both the branching ratio and the $\phi$ momentum distribution, would teach us about the strength of strong penguins which might be of great importance in the search for CP violation and for new physics at $B$ factories.
118024604
Exclusive radiative B-meson decays within minimal flavor-violating two-Higgs-doublet models
In the "Higgs basis" for a generic two-Higgs-doublet model, only one doublet gets a nonzero vacuum expectation value and, under the criterion of minimal flavor violation, the other one is fixed to be either color-singlet or color-octet, referred to, respectively, as the type-III and type-C models. Both of them can naturally avoid large FCNC transitions and provide very interesting phenomena in some low-energy processes. In this paper, we study their effects on exclusive radiative B-meson decays due to the exchange of colorless or colored charged Higgs. It is found that while constraints from the branching ratios are slightly weaker than the ones from the inclusive B -> X-s gamma decay, the isospin asymmetries in exclusive decays provide very complementary bounds on the model parameters. As the two models predict similar corrections to the dipole coefficient C-7(eff), but similar magnitudes with opposite signs to C-8(eff), the branching ratios cannot discriminate the two models, and we have to resort to the direct CP and isospin asymmetries of b -> s processes, which are more sensitive to C-8(eff). Due to the CKM factors vertical bar lambda((d))(u)vertical bar similar to vertical bar lambda((d))(t)vertical bar, the terms proportional to lambda((d))(u) make the observables of b -> d processes exhibit a different dependence on the possible new physics phase. In addition, correlations between the various observables in the exclusive B -> V gamma and the inclusive B -> X-s,X-d gamma decays are investigated, which could provide further insights into the models with more precise experimental measurements and theoretical predictions for these decays.
1542336
Extracting Cabibbo-Kobayashi-Maskawa elements in Bc semileptonic decays and heavy quark spin symmetry.
We discuss the extraction of \ensuremath{\Vert}${\mathit{V}}_{\mathit{c}\mathit{s}}$/${\mathit{V}}_{\mathit{c}\mathit{d}}$\ensuremath{\Vert},\ensuremath{\Vert}${\mathit{V}}_{\mathit{c}\mathit{s}}$/${\mathit{V}}_{\mathit{u}\mathit{b}}$\ensuremath{\Vert}, and \ensuremath{\Vert}${\mathit{V}}_{\mathit{c}\mathit{d}}$/${\mathit{V}}_{\mathit{u}\mathit{b}}$\ensuremath{\Vert} from semileptonic ${\mathit{B}}_{\mathit{c}}$ decay in the heavy quark limit. The first corrections to the corresponding ratios of the differential rates of ${\mathit{B}}_{\mathit{c}}$ semileptonic decays are calculated in the zero recoil point within HQET combined with the results of QCD sum rules and chiral perturbation theory, and within the quark model. Special attention is paid to minimize the theoretical uncertainties in the procedure of extracting the ratios. We find many uncertainties can be canceled naturally in the leading level. The ratios also are insensitive to the QCD energy scale \ensuremath{\mu} in the next-to-leading level. The result is potentially important for extracting CKM elements from future measurements at the CERN LHC.
118135338
CP violation induced by the interference of scalar and vector resonances in three-body decays of bottom mesons
Large CP violation is an interesting phenomenon both theoretically and experimentally. Last year, LHCb Collaboration found in some three-body decays of bottom mesons that large CP violations appear in regions of the Dalitz plots that are not dominated by contributions from narrow resonances. In this paper, we present a mechanism which can induce such kind of large CP violations. In this mechanism, large localized CP asymmetries in phase space can be induced by the interference of two intermediate resonances with different spins. We also apply this mechanism to the decay channel $B^\pm\to K^\pm \pi^+\pi^-$.
1941882
Reexamining charmless B ---> PV decays in QCD factorization approach
Using the QCD factorization approach, we reexamine the two-body hadronic charmless $B$-meson decays to final states involving a pseudoscalar~($P$) and a vector~($V$) meson, with inclusion of the penguin contractions of spectator-scattering amplitudes induced by the $b\to D g^\ast g^\ast$~(where $D=d$ or $s$, and $g^\ast$ denotes an off-shell gluon) transitions, which are of order $\alpha_s^2$. Their impacts on the CP-averaged branching ratios and CP-violating asymmetries are examined. We find that these higher order penguin contraction contributions have significant impacts on some specific decay modes. Since $B\to \pi K^{\ast}$, $K \rho$ decays involve the same electro-weak physics as $B\to \pi K$ puzzles, we present a detailed analysis of these decays and find that the five R-ratios for $B\to \pi K^{\ast}$, $K \rho$ system are in agreement with experimental data except for $R(\pi K^*)$. Generally, these new contributions are found to be important for penguin-dominated $B\to PV$ decays.
118727023
Predictive AdS/QCD Model for Mass Spectra of Mesons with Three Flavors
The predictive soft-wall AdS/QCD model with a modified 5D metric at the infrared region is constructed to obtain a nontrivial dilaton solution for three flavor quarks u, d and s. Such a model is shown to incorporate both the chiral symmetry breaking and linear confinement. After considering some high-order terms including the U(1)(L) x U(1)(R) chiral symmetry breaking term, we find that the resulting predictions for the SU(3) octet and singlet resonance states of pseudoscalar, scalar, vector and axial-vector mesons agree well with the experimentally confirmed resonance states. Contributions from the instanton effects given by the determinant term are also discussed. It is observed that the chiral symmetry breaking phenomena of SU(3)(L) x SU(3)(R) and U(1)(L) x U(1)(R) can be well described in this model, while the SU(3) flavor symmetry breaking effect due to quark mass difference in the source term is not enough to explain all of the current experimental data.
119272630
Charmless B-s -> PP, PV, VV decays based on the six-quark effective Hamiltonian with strong phase effects II
We provide a systematic study of charmless B-s -> PP, PV, VV decays (P and V denote pseudoscalar and vector mesons, respectively) based on an approximate six-quark operator effective Hamiltonian from QCD. The calculation of the relevant hard-scattering kernels is carried out, the resulting transition form factors are consistent with the results of QCD sum-rule calculations. By taking into account important classes of power corrections involving "chirally enhanced" terms and the vertex corrections as well as weak annihilation contributions with non-trivial strong phase, we present predictions for the branching ratios and CP asymmetries of B-s decays into PP, PV and VV final states, and also for the corresponding polarization observables in VV final states. It is found that the weak annihilation contributions with non-trivial strong phase have remarkable effects on the observables in the color-suppressed and penguin-dominated decay modes. In addition, we discuss the SU(3) flavor symmetry and show that the symmetry relations are generally respected.
118688249
Quadratic Gravitational Lagrangian with Torsion Can Give Possible Explanations of the Form of Galactic Rotation Curves, of the Amount of Intergalactic Lensings, and of the Accelerating Expansion of the Universe
The Quadratic Gravitational Lagrangian with torsion provides us with a richer number of solutions than the Einstein-Hilbert Lagrangian does. With proper interpretation, these solutions, together, seem to give good explanations of the form of the galactic rotation curves, of the amount of intergalactic gravitational lensings, and of the accelerating expansion of the Universe.
120894756
Constituent quark model study of exotic meson states
Using high precision numerical method based on Gaussian expansion method for few-body systems, we studied the spectra of possible exotic meson states composed of (Q = c, b, and q = u, d, s) in non-relativistic constituent quark model. Some newly released experimental data by the BES, Belle, BaBar Collaboration can be interpreted in our calculation. Several possible exotic states are also predicted.
118602451
QCD FACTORIZATION BASED ON SIX-QUARK OPERATOR EFFECTIVE HAMILTONIAN FROM PERTURBATIVE QCD AND CHARMLESS BOTTOM MESON DECAYS B((s)) -> pi pi, pi K, KK
The charmless bottom meson decays are systematically investigated based on an approximate six-quark operator effective Hamiltonian from perturbative QCD. It is shown that within this framework the naive QCD factorization method provides a simple way to evaluate the hadronic matrix elements of two-body mesonic decays. The singularities caused by on mass-shell quark propagator and gluon exchanging interaction are appropriately treated. Such a simple framework allows us to make theoretical predictions for the decay amplitudes with reasonable input parameters. The resulting theoretical predictions for all the branching ratios and CP asymmetries in the charmless B0, B+, Bs → ππ, πK, KK decays are found to be consistent with the current experimental data except for a few decay modes. The observed large branching ratio in B→π0π0 decay remains a puzzle though the predicted branching ratio may be significantly improved by considering the large vertex corrections in the effective Wilson coefficients. More precise measurements of charmless bottom meson decays, especially on CP violations in B → KK and Bs → ππ, πK, KK decay modes, will provide a useful test and guide us to a better understanding on perturbative and nonperturbative QCD.