Heavy-heavy form factors and generalized factorization

We reanalyze and data to extract a set of parameters which give the relevant hadronic matrix elements in terms of factorized amplitudes. Various sources of theoretical uncertainties are studied, in particular those depending on the model adopted for the form factors. We find that the fit to the branching ratios substantially depends on the model describing the Isgur-Wise function and on the value of its slope. This dependence can be reduced by substituting the with suitable ratios of non-leptonic to differential semileptonic BRs. In this way, we obtain a model-independent determination of these parameters. Using these results, the form factors at can be extracted from a fit of the . The comparison between the form factors obtained in this way and the corresponding measurements in semileptonic decays can be used as a test of (generalized) factorization free from the uncertainties due to heavy-heavy form factor modeling. Finally, we present predictions for as-yet-unmeasured and branching ratios and extract and from decays. We find MeV and MeV, in good agreement with recent measurements and lattice calculations. Received: 7 October 1998 / Revised version: 4 December 1998 / Published online: 20 May 1999     

Further Analysis of Di-gluon Fusion Mechanismfor the Decays of B→Kη′

Di-gluon fusion mechanism might account for the large branching ratios of B→Kη′. But because we know little about the effective η′ɡɡ vertex, there are large uncertainties in perturbative QCD estimations. In this paper, we try several kinds of η′ɡɡ form factors and compare the numerical results with the experiment. We find that, though we know little about η′ɡɡ form factor, if di-gluon fusion mechanism is important in B→Kη′, the branching ratios of the decays B→K^*η′ would be around 10^－5 which can be tested by future experiments.     

A study of three-prong tau decays with charged kaons

From an analysis of the ionisation energy loss of charged particles selected from a sample of 147926 candidates recorded in the OPAL detector at centre-of-mass energies near the resonance, we determine the branching ratios: where the notation refers to decay modes with or without an accompanying . The final states occurring through are treated as background in this analysis. We also examine the resonant structure of candidates. Under the assumption that the resonant structure is dominated by the K resonances, we determine: In all results, the first uncertainties are statistical and the second are systematic. Received: 9 July 1999 / Published online: 17 February 2000     

Uncertainty study of Bd(Bs)→ γν \bar{ν} Decays

B⁰(B_s) → γν\bar{ν} decays are useful to determining the decay constants f_B(f_{B_{s}}) and B(B_s) meson wave function. Using the B meson wave function determined in hadronic B(B_s) decays, we study the uncertainties due to the types of B meson wave functions. We find that the branching ratios are sensitive to the type of wave functions and input parameters, but the energy spectrum is independent. The predicted branching ratios are (0.45-1.04)× 10^-9 and (2.14-3.27)×10^-8 for B⁰ and B_s decay, respectively.     

Higgs boson couplings to bottom quarks: two-loop supersymmetry-QCD corrections

We present two-loop supersymmetry (SUSY) QCD corrections to the effective bottom Yukawa couplings within the minimal supersymmetric extension of the standard model (MSSM). The effective Yukawa couplings include the resummation of the nondecoupling corrections Deltam_{b} for large values of tanbeta. We have derived the two-loop SUSY-QCD corrections to the leading SUSY-QCD and top-quark-induced SUSY-electroweak contributions to Deltam_{b}. The scale dependence of the resummed Yukawa couplings is reduced from O(10%) to the percent level. These results reduce the theoretical uncertainties of the MSSM Higgs branching ratios to the accuracy which can be achieved at a future linear e;{+}e;{-} collider.     

A measurement of the Tau topological branching ratios

Using data collected in the DELPHI detector at LEP-1, measurements of the inclusive branching ratios for decay modes containing one, three, or five charged particles have been performed, giving the following results: where h is either a charged orK meson. The first quoted uncertainties are statistical and the second systematic. Received: 17 April 2001 / Published online: 13 June 2001     

A new approach to a global fit of the CKM matrix

We report on a new approach to a global CKM matrix analysis taking into account most recent experimental and theoretical results. The statistical framework (Rfit) developed in this paper advocates frequentist statistics. Other approaches, such as Bayesian statistics or the 95% CL scan method are also discussed. We emphasize the distinction of a model testing and a model dependent, metrological phase in which the various parameters of the theory are estimated. Measurements and theoretical parameters entering the global fit are thoroughly discussed, in particular with respect to their theoretical uncertainties. Graphical results for confidence levels are drawn in various one and two-dimensional parameter spaces. Numerical results are provided for all relevant CKM parameterizations, the CKM elements and theoretical input parameters. Predictions for branching ratios of rare K and B meson decays are obtained. A simple, predictive SUSY extension of the Standard Model is discussed. Received: 18 April 2001 / Published online: 10 August 2001     

利用波函数研究Bc介子纯轻衰变的QCD非微扰特性

B_c介子辐射性纯轻衰变的理论计算具有很大的强子型不确定性。利用3种类型的B_c介子波函数描述这种纯轻衰变的QCD非微扰特性, 并通过控制函数中参数的变化在理论上详细地计算了由介子波函数而引起的B_c介子辐射性纯轻衰变的这种强子型的不确定性。 结果表明,介子波函数的形式对计算的衰变结果有非常明显的影响, 该过程的分支比可在1.819 81×10-5～3.189 61×10-5间变化。 The radiative and pure leptonic decays of B_cmesons are of hadrons uncertainty in theoretical calculations. Using three types of the B_c meson wave functions which describe the characteristics of the QCD non perturbative and by controlling the parameters in them, the uncertainties of B_c meson decay caused by the hadron decay model are studied in detail. The theoretical results show the branching ratios are (1.819 81~3.189 61)×10-5, which are sensitive to the type of wave functions.     

Scalar mesons and scalar gluonium

We investigate the mixing of scalar mesons (S ^*, ?) with gluonium in the context of a potential model. We calculate the masses of the scalars and the branching ratios to ππ,KK, ηη and ηη′. The model can accomodate the stateG(1.59) and explain its peculiar rates. We also investigate other possibilities for gluonium mass and branching ratios and find that a gluonium state around 1 GeV may explain the unusual branching ratios in the scalar sector.     

α-decay Branching Ratios to Rotational Band of Heavy Even-even and Odd-A Nuclei

By using a simple barrier penetration approach,we predict the α-decay branching ratios to members of ground-state rotational band of heavy even-even No isotopes.We also extend our approach to calculate the α-decay branching ratios to the rotational band of heavy odd-A nuclei.The theoretical branching ratios of α-decays are found in good agreement with the available experimental data.     

Semileptonic decays of d mesons in three-flavor lattice QCD

We present the first three-flavor lattice QCD calculations for D-->pilnu and D-->Klnu semileptonic decays. Simulations are carried out using ensembles of unquenched gauge fields generated by the MILC Collaboration. With an improved staggered action for light quarks, we are able to simulate at light quark masses down to 1/8 of the strange mass. Consequently, the systematic error from the chiral extrapolation is much smaller than in previous calculations with Wilson-type light quarks. Our results for the form factors at q(2)=0 are f(D-->pi)(+)(0)=0.64(3)(6) and f(D-->K)(+)(0)=0.73(3)(7), where the first error is statistical and the second is systematic, added in quadrature. Combining our results with experimental branching ratios, we obtain the Cabibbo-Kobayashi-Maskawa matrix elements |V(cd)|=0.239(10)(24)(20) and |V(cs)|=0.969(39)(94)(24), where the last errors are from experimental uncertainties.     

Absolute measurement of hadronic branching fractions of the Ds+ meson

The branching fractions of D(s)(+/-) meson decays serve to normalize many measurements of processes involving charm quarks. Using 298 pb(-1) of e(+)e(-) collisions recorded at a center of mass energy of 4.17 GeV, we determine absolute branching fractions for eight D(s)(+/-) decays with a double tag technique. In particular we determine the branching fraction B(D(s)(+)-->K(-)K(+}pi(+))=(5.50+/-0.23+/-0.16)%, where the uncertainties are statistical and systematic, respectively. We also provide partial branching fractions for kinematic subsets of the K(-)K(+)pi(+) decay mode.     

Production and decay of the Standard Model Higgs boson at LEP200

We collect and update theoretical predictions for the production rate and decay branching fractions of the Standard Model Higgs boson that will be relevant for the Higgs search at LEP200. We make full use of the present knowledge of radiative corrections. We estimate the systematics arising from theoretical and experimental uncertainties.     

D+→η(')l+νl semileptonic decays in light-cone sum rules

We calculate the D→η transition form factor in light-cone sum rules by taking improved current correlators to avoid the pollution from the twist-3 wave function. We get consistent results of the D<'+> →η<'(')> l<'+>ν<,l> decays with the experimental data. By comparing the difference between the results of the branching ratios of D+ →η<'(')>l<'+>ν<,l> from a two-pole parameterization model and from a BZ parameterization model, we find that the two-pole model and the BZ model are comparably believable. One way is supposed for the determination of the η-η' mixing angle from the dependence of the branching ratios of D<'+> →η<'(')>l<'+>ν<,l> decays on the η-η' mixing angle.     

An Improved Analysis of Masses and Decay Constants of Heavy Flavour Mesons within Variational Approach

We employ the variational method to study the properties such as masses, decay constants, oscillation frequency and branching ratios of leptonic decays of heavy flavour mesons with linear cum coulomb Cornell potential.Gaussian function, Coulomb wave function and Airy function are taken as the trial wave-function of variational method in this study. Our analysis suggests that Gaussian trial wave-function provides results which are in close proximity with the experimental results. We also make a comparison with the results from QCD Sum rules and lattice QCD, as well as with recent PDG data.     

Systematic Calculations of α-Decay Half-Lives of Well Deformed Nuclei

We perform an extensive investigation on the α decay of heavy deformed even-even and odd-A nuclei within the multichannel cluster model. The dynamics effects of core nuclei are taken into account in dealing with the interaction matrix and the α-cluster formation. Enough decay channels are considered for convergence in solving the coupled equations. Systematic calculations have been performed for 36 even-even nuclei and 32 odd-A nuclei. The calculated results show good agreement with the available experimental data concerning total α-decay half-lives and branching ratios, including the branching ratios for high-spin states.     

Importance of Relativistic Effects for Intermediate-Z Elements： Photoionization Process of Excited Na

Using a modified R-matrix code, the fine-structure-resolved partial photoionization cross sections of excited Na （Z = 11） are calculated within the Breit-Pauli approximation. Our calculated energy levels of Na＋ and Na are in good agreement with the experimental values within 1% and the branching ratios of the J-resolved partial cross sections are consistent with the recent measurements within the experimental uncertainties. The agreements are impossible to be obtained without adequately taking into account the relativistic effects and the electron correlations together. Therefore, even for the intermediate-Z elements （e.g. Na with Z = 11）, the relativistic effects （mainly the spin-orbit interactions） should not be neglected.     

Evidence for B+ --> K0K+ and B0 --> K0K0, and measurement of the branching fraction and search for direct CP violation in B+ --> K0pi+

We present evidence for the b --> d penguin-dominated decays B+ --> K0K+ and B0 --> K0K0 in 227 x 10(6) Y(4S) --> BB decays collected with the BABAR detector. We measure the branching fractions B(B+ --> K0K+) = (1.5 +/- 0.5 +/- 0.1) x 10(-6)(< 2.4 x 10(-6)) and B(B0 --> K0K0) = [formula: see text], where the uncertainties are statistical and systematic, respectively. We also present improved measurements of the charge-averaged branching fraction B(B+ --> K0pi+) = (26.0 +/- 1.3 +/- 1.0) x 10(-6) and CP-violating charge asymmetry A(CP) (K0pi+) = -0.09 +/- 0.05 +/- 0.01), where the uncertainties are statistical and systematic, respectively.     

B → Ds(*) η (') Decays in Perturbative QCD

In this paper, we calculate the branching ratios for B⁺ → D_s⁺η, B⁺ → D_s⁺η ', B⁺ → D_s^*+η, and B⁺ → D_s^*+η ' decays by employing the perturbative QCD (pQCD) factorization approach. Under the two kinds of η-η' mixingschemes, the quark-flavor mixing scheme and the singlet-octet mixingscheme, we find that the calculated branching ratios agree well withthe currently available experimental upper limits. We also consider the so called ``f_{D_s} puzzle', by using two groups of parameters about the D^(*)_s meson decay constants, that are f_{D_s}=241 MeV, f_{D^*_s}=272 MeV and f_{^D_s=}274 MeV, f_{D^*_s}=312 MeV, to calculate the branching ratios for theconsidered decays. We find that the results change 30% by usingthese two different kinds of paramters.     

Probing γWW couplings through radiative W-decays

We investigate the possibilities of probing γWW couplings through W → γff′ by computing the branching ratios for various polarization channels of W and γ, allowing for the most general γWW couplings. The bounds on the possible deviations of γWW couplings from their standard model values can be improved if the branching ratios for the decays of W's with positive and negative helicities can be separately measured.