Engineering topics
Hyodo, Tetsuo
Publications and source records attributed to Hyodo, Tetsuo.
Weak decays of heavy hadrons into dynamically generated resonances
In this study, we present a review of recent works on weak decay of heavy mesons and baryons with two mesons, or a meson and a baryon, interacting strongly in the final state. The aim is to learn about the interaction of hadrons and how some particular resonances are produced in the reactions. It is shown that these reactions have peculiar features and act as filters for some quantum numbers which allow to identify easily some resonances and learn about their nature. The combination of basic elements of the weak interaction with the framework of the chiral unitary approach allow for an interpretation of results of many reactions and add a novel information to different aspects of the hadron interaction and the properties of dynamically generated resonances.
Origin and compositeness of baryons in chiral dynamics
The structure of baryon resonances is discussed in the dynamical approach with chiral symmetry. Defining the compositeness of a bound state through the field renormalization constant in Yukawa theory, we show that the bound state generated by an energy-independent interaction is a purely composite particle, while the energy dependence of the chiral interaction induces some elementary component through the renormalization procedure. The quantitative measure of the compositeness clarifies the molecule structure of the bound state in the natural renormalization scheme, introduced by the constraint on the loop function.
Exotics from Heavy Ion Collisions
Discriminating hadronic molecular and multi-quark states is a long standing problem in hadronic physics. We propose here to utilize relativistic heavy ion collisions to resolve this problem, as exotic hadron yields are expected to be strongly affected by their structures. Using the coalescence model, we find that the exotic hadron yield relative to the statistical model result is typically an order of magnitude smaller for a compact multi-quark state, and larger by a factor of two or more for a loosely bound hadronic molecule. We further find that some of the newly proposed heavy exotic states could be produced and realistically measured at RHIC and LHC.
{Lambda}* hypernuclei with chiral dynamics
As a strangeness S = -1 and baryon number B = 2 system, the two-body bound state of {Lambda}* = {Lambda}(1405) and a nucleon is studied. To solve the {Lambda}*N system, we construct the {Lambda}*N potential by extending the Juelich model with couplings estimated in the chiral unitary approach. We have the {Lambda}*N quasi-bound state with the mass, M{sub {Lambda}}*N{approx}2366 MeV which is shallowly bound with the binding energy B{approx}9 MeV in terms of the K-barNN system. Decay width of the fall apart process, where the {Lambda}*N resonance decays to {pi}{Sigma}N with a nucleon being as a spectator, is estimated to be {Gamma}{sub F.A}{approx}49 MeV.
Probing internal structure of {Lambda}(1405) in meson-baryon dynamics with chiral symmetry
The internal structure of the resonant {Lambda}(1405) state is investigated based on meson-baryon coupled-channels chiral dynamics, by evaluating density distributions obtained from the form factors of the {Lambda}(1405) state. The form factors are extracted from current-coupled scattering amplitudes in which the current is coupled to the constituent hadrons inside {Lambda}(1405). Using several probe interactions and channel decomposition, we find that the resonant {Lambda}(1405) state is dominantly composed of widely spread K-bar around N, with a small fraction of the escaping {pi}{Sigma} component.
Determination of the {pi}{Sigma} scattering lengths from the weak decays of {Lambda}{sub c}
The scattering lengths of the {pi}{Sigma} systems are key quantities in understanding the structure of the {Lambda}(1405) resonance and the subthreshold extrapolation of the KN interaction. We demonstrate that the {pi}{Sigma} scattering lengths can be extracted from the threshold cusp phenomena in the weak {Lambda}{sub c}{yields}{pi}{pi}{Sigma} decays, analogously with Cabibbo's method for determination of the {pi}{pi} scattering length. We show that the substantial cusp effect should be observed in the spectrum, when the {pi}{Sigma} interaction in I=0 is strongly attractive to generate a near-threshold singularity, such as a bound state or a virtual state.