247 research outputs found
Auxiliary field method and analytical solutions of the Schr\"{o}dinger equation with exponential potentials
The auxiliary field method is a new and efficient way to compute approximate
analytical eigenenergies and eigenvectors of the Schr\"{o}dinger equation. This
method has already been successfully applied to the case of central potentials
of power-law and logarithmic forms. In the present work, we show that the
Schr\"{o}dinger equation with exponential potentials of the form can also be analytically solved by using the
auxiliary field method. Formulae giving the critical heights and the energy
levels of these potentials are presented. Special attention is drawn on the
Yukawa potential and the pure exponential one
Effects of an electromagnetic quark form factor on meson properties
A form factor is introduced in the quark electromagnetic current. Its effect is analyzed on charge mean square radii and form factors in the mesonic sector. The decay of a vector meson into leptonâantilepton pair is also affected. Two different expressions for the form factors, and two different types of quark potential are tested and some relativistic kinematical corrections are proposed. In any case the introduction of a quark form factor greatly improves the agreement with experimental data. (Elsevier
Radiative transitions in mesons in a non relativistic quark model
In the framework of the non relativistic quark model, an exhaustive study of
radiative transitions in mesons is performed. The emphasis is put on several
points. Some traditional approximations (long wave length limit, non
relativistic phase space, dipole approximation for E1 transitions, gaussian
wave functions) are analyzed in detail and their effects commented. A complete
treatment using three different types of realistic quark-antiquark potential is
made. The overall agreement with experimental data is quite good, but some
improvements are suggested.Comment: 42 pages, 2 figure
Hybrid meson masses and the correlated Gaussian basis
We revisited a model for charmonium hybrid meson with a magnetic gluon [Yu.
S. Kalashnikova and A. V. Nefediev, Phys. Rev. D {\bf 77}, 054025 (2008)] and
improved the numerical calculations. These improvements support the hybrid
meson interpretation of X(4260). Within the same model, we computed the hybrid
meson mass with an electric gluon which is resolved to be lighter. Relativistic
effects and coupling channels decreased also the mass.Comment: 9 pages, 20 figures ; accepted for publication in Phys. Rev.
Electromagnetic splitting for mesons and baryons using dressed constituent quarks
Electromagnetic splittings for mesons and baryons are calculated in a
formalism where the constituent quarks are considered as dressed
quasiparticles. The electromagnetic interaction, which contains coulomb,
contact, and hyperfine terms, is folded with the quark electrical density. Two
different types of strong potentials are considered. Numerical treatment is
done very carefully and several approximations are discussed in detail. Our
model contains only one free parameter and the agreement with experimental data
is reasonable although it seems very difficult to obtain a perfect description
in any case.Comment: 14 pages, Revised published versio
Further developments for the auxiliary field method
The auxiliary field method is a technique to obtain approximate closed
formulae for the solutions of both nonrelativistic and semirelativistic
eigenequations in quantum mechanics. For a many-body Hamiltonian describing
identical particles, it is shown that the approximate eigenvalues can be
written as the sum of the kinetic operator evaluated at a mean momentum
and of the potential energy computed at a mean distance . The quantities
and are linked by a simple relation depending on the quantum
numbers of the state considered and are determined by an equation which is
linked to the generalized virial theorem. The (anti)variational character of
the method is discussed, as well as its connection with the perturbation
theory. For a nonrelativistic kinematics, general results are obtained for the
structure of critical coupling constants for potentials with a finite number of
bound states.Comment: New improved presentatio
Towers of hybrid mesons
A hybrid meson is a quark-antiquark pair in which, contrary to ordinary
mesons, the gluon field is in an excited state. In the framework of constituent
models, the interaction potential is assumed to be the energy of an excited
string. An approximate, but accurate, analytical solution of the
Schr\"{o}dinger equation with such a potential is presented. When applied to
hybrid charmonia and bottomonia, towers of states are predicted in which the
masses are a linear function of a harmonic oscillator band number for the
quark-antiquark pair. Such a formula could be a reliable guide for the
experimental detection of heavy hybrid mesons.Comment: 3 figure
Tetraquark bound states in a constituent quark model and the nature of the a_0(980) and f_0(980)
In this work we study tetraquark bound states in the framework of the
constituent quark model of Ref. [2], which has been used for the description of
non-strange two- and three-baryon systems and later on applied to the hadron
spectra.Comment: Contribution to the MESON 2002 Workshop. Krakow 24-28 May 200
Full nuclear field theory treatment of two-particle-one-hole-excitations
The nuclear field theory series is summed up to all orders of perturbation theory including only Tamm-Dancoff vertices for the case of two-particle-one-hole-excitations. It is found that the theory gives the same results as those provided by the shell-model method, but only if all possible basis states are included in the formalism. Applicability of the theory is discussed in a simple model
- âŠ