arXiv subjects

H. Toki

Publications and source records attributed to H. Toki.

At least 91 records · Page 5Linked to original sources

arXiv2001

Weyl symmetric representation of hadronic flux tubes in the dual Ginzburg-Landau theory

Hadronic flux-tube solutions describing the mesonic and the baryonic states within the dual Ginzburg-Landau (DGL) theory are investigated by using the dual lattice formulation in the Weyl-symmetric approach. The shape of the flux tubes is determined by placement of the color-electric Dirac-string singularity treated as a connected stack of quantized plaquettes in the dual lattice formulation. The Weyl symmetric profiles of the hadronic flux tubes are obtained by using the manifestly Weyl invariant representation of the dual gauge field.

hep-ph↗

arXiv2001

Rare radiative B decays to orbitally excited K mesons

The exclusive rare radiative B meson decays to orbitally excited axial-vector mesons K_1^*(1270), K_1(1400) and to the tensor meson K_2^*(1430) are investigated in the framework of the relativistic quark model based on the quasipotential approach in quantum field theory. These decays are considered without employing the heavy quark expansion for the s quark. Instead the s quark is treated to be light and the expansion in inverse powers of the large recoil momentum of the final K^{**} meson is used to simplify calculations. It is found that the ratio of the branching fractions of rare radiative B decays to axial vector K^*_1(1270) and K_1(1400) mesons is significantly influenced by relativistic effects. The obtained results for B decays to the tensor meson K_2^*(1430) agree with recent experimental data from CLEO.

hep-ph↗

arXiv2001

Relativistic Hartree-Bogoliubov Approach for Nuclear Matter with Non-Linear Coupling Terms

We investigate the pairing property of nuclear matter with Relativistic Hartree-Bogoliubov(RHB) approach. Recently, the RHB approach has been widely applied to nuclear matter and finite nuclei. We have extended the RHB approach to be able to include non-linear coupling terms of mesons. In this paper we apply it to nuclear matter and observe the effect of non-linear terms on pairing gaps.

nucl-th↗

arXiv2001

Test of phi renormalization in nuclei through phi photoproduction

We propose an experimental procedure to find out the medium modifications of the $ϕ$ meson. The reaction is inclusive $ϕ$ photoproduction in nuclei, looking for $K^+ K^-$ pairs from the $ϕ$ decay with total momentum smaller than 100-150 $MeV/c$, which are made possible at energies of present laboratories from center of mass $ϕ$ backward production and the help of Fermi motion. We have conducted a many body calculation of the mass distribution of the $ϕ$ adapted to the experimental set up of a recent JLAB experiment where the backwards $ϕ$ photoproduction has been measured. Using recent results for the in medium properties of the $ϕ$, we find that the width of the invariant mass distribution for photoproduction on medium to heavy nuclei is larger than the free $ϕ$ width by a factor of two or more.

nucl-th↗

arXiv2001

Abelian Monopole and Center Vortex Views at the Multi-Instanton Gas

We consider full non-Abelian, Abelian and center projected lattice field configurations built up from random instanton gas configurations in the continuum. We study the instanton contribution to the $\bar{Q}Q$ force with respect to ({\it i}) instanton density dependence, ({\it ii}) Casimir scaling and ({\it iii}) whether various versions of Abelian dominance hold. We check that the dilute gas formulation for the interaction potential gives an reliable approximation only for densities small compared to the phenomenological value. We find that Casimir scaling does not hold, confirming earlier statements in the literature. We show that the lattice used to discretize the instanton gas configurations has to be sufficiently coarse ($a \approx 2\barρ$ compared with the instanton size $\barρ$) such that maximal Abelian gauge projection and center projection as well as the monopole gas contribution to the $\bar{Q}Q$ force reproduce the non-Abelian instanton-mediated force in the intermediate range of linear quasi-confinement. We demonstrate that monopole clustering also depends critically on the discretization scale confirming earlier findings based on monopole blocking.

hep-ph↗

arXiv2001

Chiral unitary theory: application to nuclear problems

In this talk we briefly describe some basic elements of chiral perturbation theory, $χPT$, and how the implementation of unitarity and other novel elements lead to a better expansion of the $T$ matrix for meson meson and meson baryon interactions. Applications are then done to the $ ππ$ interaction in nuclear matter in the scalar and vector channels, antikaons in nuclei and $K^-$ atoms, and how the $ϕ$ meson properties are changed in a nuclear medium.

nucl-th↗

arXiv2001

Antikaons in nuclei and dense nuclear matter

We present recent progress on the properties of antikaons in nuclei and dense nuclear matter as obtained from two {\bar K}N interaction models: one based on the lowest-order meson-baryon chiral lagrangian and the other derived from a meson-exchange picture.

nucl-th↗

arXiv2001

Topological structure of chiral QCD vacuum

Using the trace anomaly relation, low-energy theorem and Witten-Veneziano formula, we have developed an analytical formalism which allows one to calculate the gluon condensate, the topological susceptibility and the mass of the $η'$ meson in the chiral limit as functions of the non-perturbative vacuum energy density. It is used for numerical evaluation of the chiral QCD topology within the QCD vacuum model consisting mainly of the quantum component given by the recently proposed zero modes enhancement (ZME) model and the classical component given by the the random instanton liquid model (RILM). We sum up both contributions into the total, nonperturbative vacuum energy density. A very good agreement with the phenomenological values of the topological susceptibility, the mass of the $η'$ meson in the chiral limit and the gluon condensate has been obtained. This puts the above mentioned QCD vacuum model on a firm phenomenological ground.

hep-ph↗

arXiv2000

Chromomagnetic Catalysis of Color Superconductivity in a (2+1)-dimensional NJL Model

The influence of a constant uniform external chromomagnetic field $H$ on the formation of color superconductivity has been investigated. The consideration was performed in the framework of a (2+1)-dimensional Nambu--Jona-Lasinio model with two different four-fermionic structures responsible for $<\bar qq>$ and diquark $ $ condensates. In particular, it was shown that there exists a critical value $H_c$ of the external chromomagnetic field such that at $H>H_c$ a nonvanishing diquark condensate is dynamically created (the so-called chromomagnetic catalysis effect of color superconductivity). Moreover, external chromomagnetic fields may in some cases enhance the diquark condensate of color superconductivity.

hep-ph↗

arXiv2000

$σ$ Exchange in the NN Interaction within the Chiral Unitary Approach

We study the nucleon-nucleon interaction in the isoscalar-scalar channel using t he chiral unitary approach. The $t$-matrix of the pion-pion scattering in this c hannel is summed up to all orders using the B-S equation. We find that the calcu lated results at long distances are close to those of the $σ$-exchange inte raction. In addition, there appears a shorter range repulsion in this channel.

nucl-th↗

arXiv2000

Rare radiative B decay to the orbitally excited K_2^*(1430) meson

The exclusive rare radiative B meson decay to the orbitally excited tensor K_2^*(1430) meson is investigated in the framework of the relativistic quark model based on the quasipotential approach in quantum field theory. The calculated branching ratio BR(B --> K_2^*(1430)γ)=(1.7\pm 0.6)\times 10^{-5} as well as the ratio BR(B --> K_2^*(1430)γ)/BR(B --> K^*(892)γ)=0.38\pm 0.08 is found in a good agreement with recent experimental data from CLEO.

hep-ph↗

arXiv2000

Chiral Unitary Approach to the Kaon Nucleus Interaction and Kaonic Atoms

We review recent work on various topics related to the modification of kaon properties in nuclei. After a brief exposition of the kaon-nucleon and kaon-nucleus interaction, results from the application to kaonic atoms, renormalization of the f0 and a0 scalar resonances in nuclei and phi decay in the nucleus are shown.

nucl-th↗

arXiv2000

Roles of quark-pair correlations in baryon structure and non-leptonic weak transitions of hyperon

Roles of quark-pair correlations in the baryon structure and the hyperon non-leptonic weak decay are studied within the non-relativistic constituent quark model. We construct the SU(3) ground state baryons by solving the three body problem rigorously with the confinement force and the short range spin-dependent attraction. We emphasize the importance of the $s=0$ quark-quark correlation to reproduce the $ΔI=1/2$ enhancement of the hyperon decay, and demonstrate that resulting static properties as well as the decay amplitudes agree with the experiments, if we deal with the $s=0$ correlation properly. Special attention is also put on the consequences of the SU(6) spin-flavor symmetry breaking due to the $s=0$ correlation. Calculated magnetic moments are the almost same as the naive SU(6) predictions in spite of the existence of the strong correlations.

nucl-th↗

arXiv2000

The phi --> pi^+ pi^- and phi radiative decays within a chiral unitary approach

We report on recent results on the decay of the phi into pi^+ pi^- and phi radiative decays into pi^0 pi^0 gamma and pi^0 eta gamma, which require the consideration of the final state interaction of a pair of mesons in a region inaccessible to Chiral Perturbation Theory. By using nonperturbative chiral unitary methods for the meson meson interaction we can obtain the corresponding decay widths and the results are compared with recent experimental data.

hep-ph↗

arXiv1999

Quark Confinement Physics in Quantum Chromodynamics

We study abelian dominance and monopole condensation for the quark confinement physics using the lattice QCD simulations in the MA gauge. These phenomena are closely related to the dual superconductor picture of the QCD vacuum, and enable us to construct the dual Ginzburg-Landau (DGL) theory as an useful effective theory of nonperturbative QCD. We then apply the DGL theory to the studies of the low-lying hadron structure and the scalar glueball properties.

hep-ph↗

arXiv1999

Quark mean field model for nuclear matter and finite nuclei

We study nuclear matter and finite nuclei in terms of the quark mean field (QMF) model, in which we describe the nucleon using the constituent quark model. The meson mean fields, in particular the sigma meson, created by other nucleons act on quarks inside a nucleon and change the nucleon properties in nuclear medium. The QMF model predicts an increasing size of the nucleon as well as a reduction of the nucleon mass in the nuclear environment. The present model is applied to study the properties of finite nuclei after fixing all the parameters by the nuclear matter properties, and it is found to give satisfactory results on the nuclear properties.

nucl-th↗

arXiv1999

Photoproduction of meson and baryon resonances in a chiral unitary approach

By means of a coupled channel non-perturbative unitary approach, it is possible to extend the strong constrains of Chiral Perturbation Theory to higher energies. In particular, it is possible to reproduce the lowest lying resonances in meson-meson scattering up to 1.2 GeV using the parameters of the O(p^2) and O(p^4) Chiral Lagrangian. The meson baryon sector can also be tackled along similar lines. We report on an update of these results showing some examples of photon induced reactions where the techniques have been recently applied.

nucl-th↗

arXiv1999

Systematic Study of Triaxial Deformation in the Relativistic Mean Field Theory

We use the relativistic mean field (RMF) theory to systematically study the change of deformation of even-even nuclei in the proton-rich Xe region. We investigate the appearance of triaxial deformation in 25 nuclei in the region covering Z=50-58 and N=64-72 by performing constrained, triaxially symmetric RMF calculations of their energy surfaces. We include pairing correlations using the BCS formalism. We find that the Sn isotopes are spherical and the Te isotopes are very gamma unstable with shallow minima around gamma = 60 degrees. Adding more protons, the Xe, Ba and Ce isotopes have prolate deformations with their sizes increasing with proton number. The neutron number dependence is found to be small. We compare the calculated results with the available experimented data on the binding energy and the radii.

nucl-th↗