The crucial points of physics of light scalar mesons are discussed. The special attention is given to the chiral shielding of lightest scalar mesons and the production of the well established light scalar mesons in the φ radiative decays. Arguments in favor of the four-quark model of the a 0 (980) and f 0 (980) mesons are given. To discuss actually the nature of the putative nonet of the light ...

A generalization of the eective meson Lagrangian possessing the heavy quark symmetry to nite meson masses is employed to study the meson mass dependence of the spectrum of S{ and P wave baryons containing one heavy quark or anti-quark. These baryons are described as respectively heavy mesons or anti-mesons bound in the background of a soliton, which is constructed from light mesons. No further ...

Azimuthal distributions of η and π mesons emitted at midrapidity in collisions of 1.9 AGeV Ni+Ni and 2 AGeV Ca+Ca are studied as a function of the number of projectile-like spectator nucleons. The observed anisotropy corresponds to a negative elliptic flow signal for η mesons, indicating a preferred emission perpendicular to the reaction plane. In contrast, only small azimuthal anisotropies are...

The lowest order chiral Lagrangian successfully applied to study the interaction of the SU(3) octet of pseudo-scalar mesons is generalized to include all mesons from the SU(4) 15-plet of pseudo-scalar mesons. Exchanges of heavy vector mesons, which are indirectly taken into account via this approach, are suppressed. Unitarization in coupled channels leads to dynamical generation of resonances i...

Identifying the zero-range exchange of vector mesons as the driving force for the swave scattering of pseudo-scalar mesons off the baryon ground states, the spectrum of 3 2 − molecules is computed. We predict a strongly bound 15-plet of C = −1 states. A narrow crypto-exotic octet of charm-zero states is foreseen. In the C = +1 sector a sextet of narrow resonances is formed due to the interactio...

We use lattice methods to evaluate from first principles the spectrum of hybrid mesons produced by gluonic excitations in quenched QCD with quark masses near the strange quark mass. For the spin-exotic mesons with J = 1, 0, and 2 which are not present in the quark model, we determine the lightest state to be 1 with mass of 2.0(2) GeV. One of the goals of quantitative studies of QCD is to determ...

The crucial points of physics of light scalar mesons are discussed. The special attention is given to the chiral shielding of lightest scalar mesons and the production of the well established light scalar mesons in the φ radiative decays. Arguments in favor of the four-quark model of the a 0 (980) and f 0 (980) mesons are given. To discuss actually the nature of the putative nonet of the light ...

The following topics are considered. 1. Confinement, chiral dynamics and light scalar mesons. 2. φ-meson radiative decays about nature of light scalar resonances. Arguments in favor of the four-quark model of the a 0 (980) and f 0 (980) mesons are given. To discuss actually the nature of the putative nonet of the light scalar mesons: the red putative f 0 (600) (or σ(600)) and κ(700−900) mesons ...

The most recent b-physics results from the OPAL experiment at LEP are reviewed. A measurement of semileptonic B meson decays to narrow orbitally-excited charm mesons is presented first, followed by a study of charm production in b-hadron decays. Here, B refers to B and B mesons and their charge conjugates, and b-hadron refers to the admixture of hadrons containing a b quark produced in electron...

The lowest order chiral Lagrangian successfully applied to study the interaction of the SU(3) octet of pseudo-scalar mesons is generalized to include all mesons from the SU(4) 15-plet of pseudo-scalar mesons. Exchanges of heavy vector mesons, which are indirectly taken into account via this approach, are suppressed. Unitarization in coupled channels leads to dynamical generation of resonances i...