Covariant Classification Scheme of Hadrons

Starting from the multi-local Klein-Gordon equations with Lorentz-scalar squared-mass operator we give a covariant quark representation of the general composite mesons and baryons with definite Lorentz transformation property. The mass spectra satisfy the approximate symmetry under the tilde U(4) transformation group, including the chiral transformation as a subgroup, concerning the spinor freedom of light constituent quarks, and this symmetry predicts the existence of new type of chiral mesons and baryons out of the conventional framework in non-relativistic quark model: For example, for light qqbar systems, the scalar sigma- and axial-vector a_1-nonets, and for heavy-light Qqbar and qQbar systems the scalar and axial-vector mesons are predicted to exist as relativistic S-wave states besides the ordinary P-wave state mesons. The existence of two ``exotic'' 1^-+ meson nonets is predicted as the relativistic P-wave states in qqbar systems. For light quark baryons the extra 56 with positive parity and the extra 70 with negative parity of the static SU(6) are predicted to exist as the ground state chiral particles.Comment: proc. of "Hadron '01," Protvino, Russia, Aug, 2001. 10 pages, uses ptptex.st

Scalar Mesons and Chiral States

The essential points and physical backgrounds of the covariant level-classification scheme, based on U(12)SF * O(3,1)L, are reviewed: This scheme is extended from the non-relativistic SU(6)SF * O(3)L scheme by introducing the new SU(2)-spin (rho-spin) degree of freedom, which is necessary for covariant description of composite hadrons. Our scheme predicts the existence of new type of chiral mesons and baryons (Chiralons) out of the conventional SU(6)SF * O(3)L scheme. The sigma nonet is a typical example of chiralons to be assigned to the q qbar relativistic S-wave state. The new narrow mesons Ds(2317)/Ds(2463) are naturally assigned as the ground-state scalar and axial-vector chiralons in the c sbar system.Comment: 5 pages, proc of Hadron 200

Relation between Scattering and Production Amplitude - Case of Intermediate \sigma-Particle in \pi\pi-System

The relation between scattering and production amplitudes are investigated, using a simple field theoretical model, from the general viewpoint of unitarity and the applicability of final state interaction(FSI-) theorem. The IA-method and VMW-method, which are applied to our phenomenological analyses suggesting the \sigma-existence, are obtained as the physical state representations of scattering and production amplitudes, respectively. Moreover, the VMW-method is shown to be an effective method to obtain the resonance properties from general production processes, while the conventional analyses based on the ``universality'' of \pi\pi-scattering amplitude are powerless for this purpose.Comment: Talk at HADRON'97, the 7th int. conf. on hadron spectroscopy, BNL, August 1997. 4 pages with no figur

Property of Chiral Scalar and Axial-Vector Mesons in Heavy-Light Quark Systems

Recently we have proposed a new level-classification scheme of hadrons with a manifestly covariant framework. In this scheme the requirement of chiral symmetry on the light quark leads to a prediction of existence of new type of scalars X_B, X_D and axial-vectors X_B^*,X_D^* as the chiral partners of ground state pseudoscalar B,D and vector B^*,D^* mesons, respectively. They belong to ``relativistic S-wave states,'' and are discriminated from the conventional P-wave mesons with j_q=1/2 appearing in the heavy quark effective theory. In this talk we examine the properties of these chiral mesons: The mass-splittings between the respective chiral partners are predicted to be equal, and the decay widths of one pion emission of X_B, X_D, X_B^* and X_D^* are to take the same value due to both chiral and heavy quark symmetries. Some experimental indications for existence of X_B and X_D^* are also given, which are consistent with the above prediction.Comment: proc. of "Hadron '01," Protvino, Russia, Aug, 2001. 5 pages, uses ptptex.st