Quark dynamics and the weak non-leptonic decays of K and D mesons

Quark model predictions for K → 2π and D → Kπ decays were investigated in dynamical frameworks based on the separable approximation (SA), current algebra (CA), current algebra modified for the meson moment dependence (CAC) and current algebra with final-state interactions (CAF). Relativistic and non-relativistic quark model predictions were compared. The effective weak hamiltonian was modified by changing the relative strengths of its flavour $\text{20}\text{and}\text{84}$ parts. All these approaches were also applied to hyperon and $\text{Ω}{}^{\mathrm{?}}$ non-leptonic decays. When using standard QCD enhancement, the best approximation for K → 2π (CAC) works poorly with D → Kπ. The best approximatiob for D→Kπ (CAF) fails in the case of K → 2π. Only CAC with the $\text{84}$ piece of the hamiltonian quenched might be in agreement with studied weak decays.     

On tests of local realism by CP-violation parameters of K 0 mesons

Recently various papers have proposed to test local realism (LR) by considering electroweak CP-violation parameters values in neutral pseudoscalar meson systems. Considering the large interest for a conclusive test of LR and the experimental accessibility to these tests, in this paper we critically consider these results showing how they, albeit that they are very interesting, require anyway additional assumptions and therefore cannot be considered conclusive tests of LR.Received: 25 October 2004, Revised: 30 March 2005, Published online: 31 May 2005PACS: 13.20.Eb, 03.65.Bz     

Quark dynamics and non-leptonic weak decays of K and D mesons (II)

This paper presents an investigation of quark dynamics, which, combined with soft-gluonic corrections, leads to fits of K → 2π (D → Kπ) decay amplitudes.     

Quark potentials for mesons in the Klein-Gordon equation

Two relativistic potential models are applied to describe meson spectroscopy in a unified way, encompassing both light and heavy quark systems. A combination of linear and coulomb potentials has been investigated for Klein-Gordon equation using the WKB approximation. A power-like phenomenological potential model has also been studied in the Klein-Gordon framework. Meson masses calculated for both the potentials give a good agreement with the corresponding experimental values.     

Vector and axial-vector mesons in Quasilocal Quark Models

We consider the SU(2) Quasilocal Quark Model of the NJL-type including vector and axial-vector four-fermion interaction vertices with derivatives. The mass spectrum and a set of model-independent relations for the ground and first-excited states are calculated. The chiral-symmetry restoration sum rules in these channels are imposed for matching to QCD at intermediate energies in order to get a number of constraints on parameters of the SU(2) QQM. Received: 15 January 2003 / Accepted: 10 February 2003 / Published online: 29 April 2003     

Quark structure and weak decays of heavy mesons

We construct a cellular space which has as a continuous limit the Euclidean spaceR ^N . We consider quantum mechanics on this cellular space and we examine in particular an harmonic oscillator and a free particle on the cellularR ¹,R ² respectively. In both cases we find that the energy spectrum is bounded from above.Partially supported by CEC Science project No SC1-CT91-0729     

Quark model predictions on the masses of heavier vector mesons

We use the quark model considerations of Federman, Rubinstein and Talmi and the relation (m _ψ/m _ϕ)≃(m _ϒ/m _ψ)≃(m _ϒ/m _ϒ) to compute the masses of beautiful and tasty vector mesons.     

Quark model for the production of pseudoscalar mesons in annihilation

A modification of the quark model for annihilation permits the calculation of the relative probabilities of all observed channels with pseudoscalar mesons. Agreement with the experimental data on proton-antiproton annihilations at rest into three and more mesons is obtained.     

Quark diagram analysis of bottom meson decays emitting pseudoscalar and vector mesons

This paper presents the two body weak nonleptonic decays of B mesons emitting pseudoscalar (P) and vector (V) mesons within the framework of the diagrammatic approache at flavor SU(3) symmetry level. Using the decay amplitudes, we are able to relate the branching fractions of B → PV decays induced by both b → c and b → u transitions, which are found to be well consistent with the measured data. We also make predictions for some decays, which can be tested in future experiments.     

An investigation of hadronization mechanism at a Z~0 factory

We briefly review the hadronization pictures adopted in the LUND String Fragmentation Model (LSFM),Webber Cluster Fragmentation Model (WCFM) and Quark Combination Model (QCM),respectively.Predictions of hadron multiplicity,baryon to meson ratios and baryon-antibaryon flavor correlations,especially those related to heavy hadrons at a Z 0 factory obtained by LSFM and QCM,are reported.     

The interaction of K mesons with nuclei

The experimental data for K⁻ capture by nuclei is interpreted in terms of K⁻ nucleon scattering amplitudes in a region of negative relative kinetic energy. It is shown that constant scattering length solutions which represent the data in the region of positive relative kinetic energy up to 100 MeV do not satisfactorily describe the interaction with bound nucleons and a modified scattering length solution is proposed. Measured values of the widths of K-mesic X-ray lines which require a strongly attractive K⁻ nucleons optical potential are successfully interpreted in terms of K⁻N scattering lengths appropriate for bound nucleons. The information obtainable about relative neutron and proton density distributions in the nuclear periphery from studies of this kind is discussed. The need for more data on interaction of K⁻ in hydrogen at low kinetic energies and at rest and in other elements at rest is emphasised.     

The semileptonic form factors of B and D mesons in the Quark Confinement Model

The form factors of the weak currents, which appear in the semileptonic decays of the heavy pseudoscalar mesons are calculated within the quark confinement model by taking into account, for the first time, the structure of heavy-meson vertex and the finite quark mass contribution in the heavy-quark propagators. The results are in quite good agreement with the experimental data. Received: 9 June 2000 / Accepted: 15 August 2000     

Quark microscopic picture for vector and pseudoscalar mesons in the nucleon and their quasielastic knockout by high-energy electrons

A technique for projecting a multiquark wave function in the microscopic model of a ³P⁰ scalar fluctuation onto the virtual-decay channels N → N + ρ and N → N + π is formulated (at a more general level for the latter than previously). The amplitude for the electromagnetic transition ρ + γ _T ^* → π in electron-induced quasielastic rho-meson knockout followed by rho-meson conversion to a pion is considered. Theoretical results obtained in this way are contrasted against available experimental data, and reasonable agreement is found for cross-section values. This confirms a universal character of the ³P₀ model. The precision of relevant experiments is as yet insufficient for comparing the momentum distribution of the rho meson from the channel N → N + ρ with its theoretical counterpart.