675 research outputs found
Hadronic few-body systems in chiral dynamics, -- Few-body systems in hadron physics --
Hadronic composite states are introduced as few-body systems in hadron
physics. The resonance is a good example of the hadronic
few-body systems. It has turned out that can be described by
hadronic dynamics in a modern technology which incorporates coupled channel
unitarity framework and chiral dynamics. The idea of the hadronic
composite state of is extended to kaonic few-body states. It is
concluded that, due to the fact that and have similar interaction
nature in s-wave couplings, there are few-body quasibound states with
kaons systematically just below the break-up thresholds, like , and , as well as as a quasibound state
and and as .Comment: 8 pages, 2 figures, contribution to 20th International IUPAP
Conference on Few-Body Problems in Physics (FB20), 20-25 August 2011,
Fukuoka, Japa
Baryon resonances as dynamically generated states in chiral dynamics
We discuss baryon resonances which are dynamically generated in hadron
dynamics based on chiral coupled channels approach. With the dynamical
description of the baryon resonance, we discuss the origin of the resonance
pole, finding that for the description of N(1535) some other components than
meson and baryon are necessary. Since the chiral unitary model provides a
microscopic description in terms of constituent hadrons, it is straightforward
to calculate transition amplitudes and form factors of resonances without
introducing further parameters. Finally we briefly discuss few-body nuclear
kaonic systems as hadronic molecular states.Comment: 6 pages, 1 figure. Talk given at the 8th International Workshop on
the Physics of Excited Nucleons (NSTAR2011), Newport News, VA, USA, May
17-20, 201
Negative Parity Baryons in the QCD Sum Rule
Masses and couplings of the negative parity excited baryons are studied in
the QCD sum rule. Separation of the negative-parity spectrum is proposed and is
applied to the flavor octet and singlet baryons. We find that the quark
condensate is responsible for the mass splitting of the ground and the
negative-parity excited states. This is expected from the chiral symmetry and
supports the idea that the negative-parity baryon forms a parity doublet with
the ground state. The meson-baryon coupling constants are also computed for the
excited states in the QCD sum rule. It is found that the \pi NN^* coupling
vanishes in the chiral limit.Comment: 13pp, LaTeX, 1 EPS figure, uses epsf.sty, Talk given by M.O. at
CEBAF/INT workshop "N* physics", Seattle, September (1996), to appear in the
proceeding
Chiral condensate at finite density using chiral Ward identity
In order to study partial restoration of the chiral symmetry at finite
density, we investigate the density corrections of the chiral condensate up to
next-leading order of density expansion using the chiral Ward identity and an
in-medium chiral perturbation theory. In our study, we assume that all the
in-vacuum quantities for the pion, the nucleon and the pi N interaction are
determined and focus on density expansion of the in-medium physical quantities.
We perform diagrammatic analysis of the correlation functions which provide the
in-medium chiral condensate. This density expansion scheme shows that medium
effects to the chiral condensate beyond the linear density come from density
corrections to the pi N sigma term as a result of the interactions between pion
and nucleon in nuclear matter. We also discuss that higher density
contributions beyond order of rho^2 cannot be fixed only by the in-vacuum pi N
dynamics but we need NN two-body dynamics in vacuum to fix divergence appearing
in the calculation of the rho^2 dependence of the chiral condensate with the pi
N dynamics.Comment: 13 pages, 9 figure
A new N* resonance as a hadronic molecular state
We report our recent work on a hadronic molecule state of the KbarKN system
with I=1/2 and J^P=1/2^+. We assume that the Lambda(1405) resonance and the
scalar mesons, f_{0}(980), a_{0}(980), are reproduced as quasi-bound states of
KbarN and KbarK, respectively. Performing non-relativistic three-body
calculations with a variational method for this system, we find a quasibound
state of the KbarKN system around 1910 MeV below the three-body breakup
threshold. This state corresponds to a new baryon resonance of N* with
J^P=1/2^+. We find also that this resonance has the cluster structure of the
two-body bound states keeping their properties as in the isolated two-particle
systems. We also briefly discuss another hadronic molecular state composed by
two Kbar and one N, which corresponds to a Xi^* resonance.Comment: Talk given at Workshop on the Physics of Excited Nucleon --
NSTAR2009, Beijing April 19 - 22, 200
Structure of Lambda(1405) and chiral dynamics
We report on a recent theoretical work on the structure of the Lambda(1405)
resonance within a chiral unitary approach, in which the resonance is
dynamically generated in meson-baryon scattering. Studying the analytic
structure of the scattering amplitude, we have found that there are two poles
lying around energies of Lambda(1405) with different widths and couplings to
the meson-baryon states. We discuss reactions to conform the double pole
structure in experiment and elastic K^- p scattering at low energies.Comment: 4 pages, LaTeX, 2 eps figures. Talk given at 10th International
Conference on the Structure of Baryons (Baryon 2004) at Palaiseau (France),
25-29 October 200
QCD Sum Rules and 1/ expansion
The 1/ arguments are developed to classify the hadronic states in the
correlators. Arguments applied to the meson correlator enable to
separate the instanton, glueball, and, in particular, the scattering
states by from both 2q and 4q correlators. The bare resonance pole with
no mixing effects are analyzed with the QCD sum rules (QSR). The results
suggest the existence of nontrivial correlation for the mass reduction of 4q
system.Comment: Presented at at YITP International Symposium Fundamental Problems in
Hot and / or Dense QCD, Kyoto, Japan, 3-6 Mar 200
- …