Claude Semay

Diquonia and potential models

We present four new quark-quark potentials, developed in the framework of the nonrelativistic quark model (NRQM), which can reproduce quite well the spectra of mesons and baryons. They contain a central part which is of type “Coulomb+linear” or “Coulomb +2/3-power”, and a strong but smooth hyperfine term. With these four potentials and the one proposed by Bhaduri et al., we have calculated masses and decay properties of some interesting diquonia (q2q−2 mesons). We have not found appreciable difference between the results of the five potentials considered, indicating that the properties of diquonia are, to a large extent, potential-independent in the NRQM.

THE BC MESON LIFETIME IN THE LIGHT-FRONT CONSTITUENT QUARK MODEL

Abstract We present an investigation of the total decay rate of the (ground state) B c meson within the framework of the relativistic constituent quark model formulated on the light-front (LF). The exclusive semileptonic (SL) and nonleptonic (NL) beauty and charm decays of the B c meson are described through vector and axial hadronic form factors, which are calculated in terms of quark model LF wave functions. The latter ones are derived via the Hamiltonian LF formalism using as input the update constituent quark models. The inclusive SL and NL partial rates are calculated within a convolution approach inspired by the partonic model and involving the same B c wave function which is used for evaluation of the exclusive modes. The framework incorporates systematically 84 exclusive and 44 inclusive partial rates corresponding to the underlying b → c and c → s quark decays. We find τ B c =0.59±0.06 ps where the theoretical uncertainty is dominated by the uncertainty in the choice of LF wave functions and the threshold values for the hadron continuum. For the branching fractions of the B + c → J / ψμ + ν μ and B c + → J / ψπ + decays we obtain 1.6% and 0.1%, respectively.We present an investigation of the total decay rate of the (ground state) B_c meson within the framework of the relativistic constituent quark model formulated on the light-front (LF). The exclusive semileptonic (SL) and nonleptonic (NL) beauty and charm decays of the B_c meson are described through vector and axial hadronic form factors, which are calculated in terms of a constituent quark model LF wave functions. The latter ones are derived via the Hamiltonian LF formalism using as input the update versions of the constituent quark model. The inclusive SL and NL partial rates are calculated within a convolution approach inspired by the partonic model and involving the same B_c wave function which is used for evaluation of the exclusive modes. The framework incorporates systematically 84 exclusive and 44 inclusive partial rates corresponding to the underlying \bar{b}\to\bar{c} and c\to s quark decays. Based on our approach we find\tau_{B_c}=0.59 \pm 0.06 ps where the theoretical uncertainty is dominated by the uncertainty in the choice of LF wave functions and the threshold values for the hadron continuum. For the branching fractions of the B^+_c \to J/\psi\mu^+\nu_{\mu} and B_c^+\to J/\psi\pi^+ decays we obtain 1.6 % and 0.1 %, respectively.

Systematics of\(L = 0q^2 \bar q^2 \) systems

AbstractUsing the interquark potential due to Bhaduri et al., the energies of all

Spectrum and decay properties of diquonia

L = 0q^2 \bar q^2

Light meson spectra and instanton-induced forces

systems are calculated for any value of the total spinS and for any value of the physical flavors:u, d, s, c, b. A harmonic oscillator basis up to 8 quanta is used to solve the four-body problem within a non-relativistic quark model. The corresponding energies are compared to the meson-meson threshold energies in order to search for stable multiquarks some of them are proposed.

The quantum N-body problem and the auxiliary field method

Abstract We propose eight types of quark-antiquark interactions suited to describe various meson sectors. They contain QCD inspired components: the Coulomb-like interaction, the confinement potential and an instanton interaction. These forms are supplemented with a phenomenological hyperfine energy term. The size of the constituent quarks is taken into account. We consider two different kinematics: non-relativistic and semi-relativistic. The parameters are determined by a minimization procedure on representative samples of mesons. The full spectra are calculated and the form factors for the pion and the kaon are also studied. A careful analysis of the different models is performed through a comparison with experiment and between themselves.

Semirelativistic potential model for glueball states

Using the interquark potential due to Bhaduri et al., the properties ofq2q−2 systems are studied within a non-relativistic quark model. A systematics over the various flavorsu, d, s, c, b, over the total spinS and over the orbital angular momentumL=0, 1, 2, 3 is carried out, while the parity is taken as the natural one. Not only the spectrum, but also the decay properties of each state are evaluated and the wave functions are analyzed in term of dumbbell structure. We propose a number of new resonances which could have a very narrow width.

Unified meson-baryon potential

The relations existing between the auxiliary field (einbein field) formalism and the spinless Salpeter equation are studied in the case of two particles with the same mass, interacting via a confining potential. The problem of non-orthogonality for radial excited states in the auxiliary field formalism is discussed and found to be non-crucial. It is shown that the classical equations of motion of the rotating string model, derived from the QCD lagrangian, reduce exactly to the classical equations of motion of the phenomenological semirelativistic flux tube model, provided all auxiliary fields are eliminated correctly from the rotating string hamiltonian.