8 research outputs found
Mass of Y(3940) in Bethe-Salpeter equation for quarks
The general form of the Bethe-Salpeter wave functions for the bound states
composed of two vector fields of arbitrary spin and definite parity is
corrected. Using the revised general formalism, we investigate the observed
\emph{Y}(3940) state which is considered as a molecule state consisting of
. Though the attractive potential between and
including one light meson (, , , )
exchange is considered, we find that in our approach the contribution from
one- exchange is equal to zero and consider SU(3) symmetry breaking. The
obtained mass of \emph{Y}(3940) is consistent with the experimental value.Comment: 19 pages, 4 figures, 1 tabl
Mass and width of unstable molecular state in quantum field theory
Applying resonance theory in the framework of relativistic quantum field
theory, we investigate the temporal evolution of molecular state composed of
two vector mesons as determined by the total Hamiltonian. Then exotic meson
resonance is considered as a mixed state of two unstable molecular
states and , and the corrected mass and
width for resonance are calculated. In this actual calculation, we
minutely show how to obtain the corrections for resonance and to exhibit the
key features of dispersion relation in a new Feynman diagram. The numerical
results are consistent with the experimental values
Quark Mass Ratios in ChPT with the Difference of Quark Condensates Considered
The chiral effective Lagrangian for pseudoscalar nonet is constructed in
consideration of isospin breaking. And the difference of quark condensates is
taken accounted. The SU(3) singlet eta0 is not taken as Goldstone-boson. The
mixing with and without isospin symmetry is considered. The quark mass ratios
are obtained through solving the mass equations of mesons. We estimate the
change of quark mass ratios according to the change of the masses of pion+ and
kaon+ to see how the electromagnetic corrections affect our results. It turn
out that massless up quark is possible. The upper limit for mu/md is around
0.39. 2ms/(mu+md)=24.23~25.12. The values for quark condensate ratios and other
constants are limited in narrow ranges.Comment: 10 page
Development of Bethe-Salpeter theory for dealing with unstable system
In the framework of relativistic quantum field theory, the solution of
homogeneous Bethe-Salpeter equation for two-body bound state can not describe
unstable system, so we develop Bethe-Salpeter theory to investigate resonance
which is regarded as an unstable two-body system. Based on Bethe-Salpeter wave
function, we consider the time evolution of two-body bound state determined by
the total Hamiltonian. The total matrix element for arbitrary decay channel is
expressed in terms of the Heisenberg picture, and Mandelstam's approach is
generalized to calculate the matrix element between bound states with respect
to arbitrary value of the final state energy. Some innovations to Feynman
diagram are made so that the key features of dispersion relation can be more
clearly exhibited. This new resonance theory in quantum field theory is applied
to investigate exotic particle which is considered as an unstable meson-meson
molecular state.Comment: arXiv admin note: text overlap with arXiv:2210.0156