5 research outputs found
Relativistic quark models of baryons with instantaneous forces
This is the first of a series of three papers treating light baryon resonances (up to 3 GeV) within a relativistically covariant quark model based on the three-fermion Bethe-Salpeter equation with instantaneous two- and three-body forces. In this paper we give a unified description of the theoretical background and demonstrate how to solve the Bethe-Salpeter equation by a reduction to the Salpeter equation. The specific new features of our covariant Salpeter model with respect to the usual nonrelativistic quark model are discussed in detail. The purely theoretical results obtained in this paper will be applied numerically to explicit quark models for light baryons in two subsequent papers
Nucleon matrix elements and baryon masses in the Dirac orbital model
Using the expansion of the baryon wave function in a series of products of
single quark bispinors (Dirac orbitals), the nonsinglet axial and tensor
charges of a nucleon are calculated. The leading term yields in
good agreement with experiment. Calculation is essentially parameter-free and
depends only on the strong coupling constant value . The importance
of lower Dirac bispinor component, yielding 18% to the wave function
normalization is stressed. As a check, the baryon decuplet masses in the
formalism of this model are also computed using standard values of the string
tension and the strange quark mass ; the results being in a good
agreement with experiment.Comment: 8 pages, 2 tables; LaTeX2
Quark--antiquark states and their radiative transitions in terms of the spectral integral equation. {\Huge II.} Charmonia
In the precedent paper of the authors (hep-ph/0510410), the states
were treated in the framework of the spectral integral equation, together with
simultaneous calculations of radiative decays of the considered bottomonia. In
the present paper, such a study is carried out for the charmonium
states. We reconstruct the interaction in the -sector on the basis of
data for the charmonium levels with , , ,
, , and radiative transitions
, , ,
and , ,
. The levels and their wave functions
are calculated for the radial excitations with . Also, we determine the
component of the photon wave function using the annihilation
data: , , , , , and perform the calculations of the partial widths of
the two-photon decays for the states: , ,
, and states:
, , . We discuss the status of the recently observed states
X(3872) and Y(3941): according to our results, the X(3872) can be either
or , while Y(3941) is .Comment: 24 pages, 9 figure