[en] Because the derivation of the constituent quark representation, from QCD remains an open, challenging problem, many models leading to chiral symmetry breaking have been proposed. An alternative to such models is presented which utilizes QCD sum rules. This QCD calculation is based on the observation that in a static chromoelectric background a light QCD quark resembles the light constituent quark in a heavy meson with the quantum number to the Qq pair. QCD sum rule techniques and the heavy quark effective theory are used to study the light quark energy and momentum distributions in the constituent quark. Results of QCD evolution will also be presented to show the effects of the perturbative gluon dressing of the light quark. Implications for the decays of a heavy meson will be discussed

[en] A unitary framework based on the Bakamjian-Thomas construction of relativistic quantum mechanics is used to describe two-pion scattering from threshold to 1400 MeV. The framework properly includes unitarity cuts for one-, two- and three-hadron states and provides an excellent description of the available data for ππ phase shifts and inelasticities. The role and importance of three-hadron cuts are calculated and discussed

[en] Short communications only

[en] We estimate the upper limit for hadronic corrections to the CP assymmetries in direct B⁰ decays, those with no induced flavour changing neutral currents. Our result shows that unless the KM phase is very small (sin θ<0.01), it can be determined from the measurements of CP asymmetries in direct decays. (orig.)

[en] Short communications only

[en] Starting with the covariant harmonic oscillator equation for a many particle system suggested by Kim and Noz, we discuss a relativistic generalization of the nuclear symplectic model. We apply it to a state of three spinless quarks and analyze the branching rules of the Lie algebras involved as well as the mass spectra of the system. (orig.)

[en] We calculate O(α_s) corrections to the soft, wave-function-dependent, normalization f₊(0) of the matrix element left-angle π|bar qγ^μQ|B right-angle. We find these corrections to be large and strongly dependent on the meson wave functions in the momentum region where propagators in the hard amplitude become soft. The findings are compared with recent results for the B→πl bar ν branching ratio reported by CLEO. copyright 1996 The American Physical Society

[en] It is pointed out that the correct criterion to define the legal PQCD contribution to the exclusive processes in the lightcone perturbative expansion should be based on the large off-shellness of the lightcone energy in the intermediate states. In the lightcone perturbative QCD calculation of the pion form factor, the authors find that the legal PQCD contribution defined by the lightcone energy cut saturates in the smaller Q² region compared to that defined by the gluon four-momentum square cut. This is due to the contribution by the highly off-energy-shell gluons in the end point regions of the phase space, indicating that the gluon four-momentum-square cut may have cut too much to define the legal PQCD

[en] We study the most general, relativistic, constituent q bar q meson wave function within a new covariant framework. We find that by including a tensor wave function component, a pure valence quark model is now capable of reproducing not only all static pion data (f_π,left-angle r_π² right-angle) but also the distribution amplitude, form factor [F_π(Q²)], and structure functions. Further, our generalized spin wave function provides a much better detailed description of meson properties than models using a simple relativistic extension of the S=L=0 nonrelativistic wave function

[en] It is pointed out in the example of the pion form factor that the usual factorized hard scattering amplitude T_H in perturbative QCD is derived from the light-cone time-ordered perturbative expansion. In the light-cone perturbative expansion, the natural variable to make a separation of perturbative contributions from contributions intrinsic to the bound-state wave function itself is the light-cone energy, rather than the gluon virtuality of T_H. We find that the ''legal'' PQCD contribution defined by the light-cone energy cut saturates to the full PQCD prediction without any cut in the smaller Q² region as compared to that defined by the gluon four-momentum square cut. This is due to the contribution from highly off-energy-shell gluons in the end-point regions of the phase space