We consider here a relativistic generalization of a field-theoretic model of composite hadrons with quarks as constituents proposed earlier. The quarks are assumed t o occupy fixed energy levels in hadrons at rest, with the hadron Inass being given additively in terms of the quark energies. These quark field operators for hadrons at rest are next Lorentz-boosted t o describe hadrons in motion, using the fact that quark operators are Dirac field operators with known transformation properties. Static properties of baryons are utilized to estimate the quark-field-operator parameters. The Dirac Harniltonian for the quark field operators also has a nonvanishing expression for quark-pair-creation processes. The covariant generalization of this Hamiltonian is used to describe strong-interaction vertices. The quark-field-operator parameters and the ham~onic-oscillator wave function are next utilized t o describe quantitatively the pion-nucleon coupling constant, as well as N* -+ N x , p -+ 27r, rj + 2K and K* + Rn. The results agree w~t h experimental values reasonably well, indicating that the above Hamiltonian may be the dynarnical origin of the three-particle vertices of hadronic strong interactions as well as an explanation of thc Okubo-Zweig-lizuka rule.

No abstract

We calculate the decay widths of the charmonium states, J/ψ, ψ(3686) and ψ(3770), to DD pairs, as well as the decay width of D * → Dπ, in isospin asymmetric strange hadronic matter, using a field theoretical model for composite hadrons with quark constituents. For this purpose we use the quark antiquark pair creation term of the free Dirac Hamiltonian written in terms of the constituent quark field operators, and use explicit charmonium, D,D, D * and π states to evaluate the matrix elements for the charmonium as well as D * decay amplitudes. The medium modifications of the partial decay widths of charmonium to DD pair, arising from the mass modifications of the D(D) and the charmonium states calculated in a chiral effective model, are also included. The results of the present investigations are then compared with the decay widths computed earlier, in a model using light quark pair creation in 3 P 0 state. As in 3 P 0 model, the decay amplitude in the present model is multiplied with a strength parameter for the light quark pair creation, which is fitted from the observed vacuum decay width. The effects of the isospin asymmetry, the strangeness fraction of the hadronic matter on the masses of the charmonium states and D(D) mesons and hence on the decay widths, have also been studied. The isospin asymmetry effect is observed to be dominant for high densities, leading to appreciable difference in the decay channels of the charmonium to D + D − and D 0D0 pairs. The decay width of D * → Dπ in the hadronic matter has also been calculated within the composite quark model in the present work, accounting for the medium modifications of the D and D * masses. The density modifications of the charmonium states and D(D * ) mesons, which are observed to be appreciable at high densities, will be of relevance in the compressed baryonic matter (CBM) experiments at the future facility of FAIR, GSI, where charmed hadrons will be produced by annihilation of antiprotons on nuclei. The interactions of the charmonium states and D(D * ) with the nuclear medium could lead to the possiblility of the formation of exotic bound states of the nuclei with the (excited) charmonium states as well as with D(D

No abstract

We consider here chiral symmetry breaking through nontrivial vacuum structure with quark antiquark condensates. We then relate the condensate function to the wave function of pion as a Goldstone mode. This simultaneously yields the pion also as a quark antiquark bound state as a localised zero mode in vacuum. We illustrate the above with Nambu Jona-Lasinio model to calculate different pionic properties in terms of the vacuum structure for breaking of exact or approximate chiral symmetry, as well as the condensate fluctuations giving rise to σ mesons.