Publications (58)157.4 Total impact

Dataset: QMCReview PPNP58 1 2007
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ABSTRACT: Using the quark–meson coupling (QMC) model, we study the density dependence of the quark and gluon condensates in nuclear matter. We show that the change of the quark condensate is mainly driven by the scalar field in the medium and that the reduction of the quark condensate is suppressed at high density, even in the meanfield approximation. The gluon condensate decreases by 4–6% at nuclear saturation density. We also give a simple relationship between the change of the quark condensate and that of a hadron mass in the medium.Modern Physics Letters A 11/2011; 13(10). · 1.11 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: Prompted by the level of accuracy now being achieved in tests of the unitarity of the CKM matrix, we consider the possible modification of the Fermi matrix element for the $\beta$decay of a neutron, including possible inmedium and isospin violating corrections. While the nuclear modifications lead to very small corrections once the BehrendsSirlinAdemolloGatto theorem is respected, the effect of the $ud$ mass difference on the conclusion concerning $V_{ud}$ is no longer insignificant. Indeed, we suggest that the correction to the value of $V_{ud}^2 \, + \, V_{us}^2 \, + \, V_{ub}^2$ is at the level of $10^{4}$.Physics Letters B 01/2011; 696. · 4.57 Impact Factor 
Article: Hyperons in nuclear matter
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ABSTRACT: The chiral version of the QMC model, in which the effect of gluon and pion exchanges is included selfconsistently, is applied to the hyperons in a nuclear medium. The hyperfine interaction due to the gluon exchange plays an important role in the inmedium baryon spectra, while the pioncloud effect is relatively small. At the quark meanfield level, the $\Lambda$ feels more attractive force than the \Sigma or \Xi in matter.03/2009;  [Show abstract] [Hide abstract]
ABSTRACT: Using the volume coupling version of the cloudy bag model, the quark–meson coupling model is extended to study the role of pion field and the properties of nuclear matter. The extended model includes the effect of gluon exchange as well as the pioncloud effect, and provides a good description of the nuclear matter properties. The relationship between the extended model and the EFT approach to nuclear matter is also discussed.Physics Letters B 07/2008; · 4.57 Impact Factor 
Article: A new molecular dynamics calculation and its application to the spectra of light and strange baryons
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ABSTRACT: A new approach based on antisymmetrized molecular dynamics is proposed to correctly take account of the manybody correlation. We applied it to the spectra of lowlying, light and strange baryons. The inclusion of the quarkquark correlation is vital to predict the precise spectra, and the semirelativistic kinematics is also important to correct the level ordering. The baryon spectra calculated by the present method is as precise as the Faddeev calculation.Journal of Physics G Nuclear and Particle Physics 06/2008; · 5.33 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We study the bound nucleon sigma term and the quark condensate in nuclear matter. In the quarkmeson coupling (QMC) model the nuclear correction to the sigma term is small and negative, i.e., it decelerates the decrease of the quark condensate in nuclear matter. However, the quark condensate in nuclear matter is controlled primarily by the scalarisoscalar $\sigma$ field. Compared to the leading term, it moderates the decrease more than that of the nuclear sigma term alone at densities around and larger than the normal nuclear matter density.European Physical Journal A 09/2006; · 2.04 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We review the effect of hadron structure changes in a nuclear medium using the quarkmeson coupling (QMC) model, which is based on a mean field description of nonoverlapping nucleon (or baryon) bags bound by the selfconsistent exchange of scalar and vector mesons. This approach leads to simple scaling relations for the changes of hadron masses in a nuclear medium. It can also be extended to describe finite nuclei, as well as the properties of hypernuclei and mesonnucleus deeply bound states. It is of great interest that the model predicts a variation of the nucleon form factors in nuclear matter. We also study the empirically observed, BloomGilman (quarkhadron) duality. Other applications of the model include subthreshold kaon production in heavy ion collisions, D and Dbar meson production in antiprotonnucleus collisions, and J/Psi suppression. In particular, the modification of the D and Dbar meson properties in nuclear medium can lead to a large J/Psi absorption cross section, which explains the observed J/Psi suppression in relativistic heavy ion collisions.Progress in Particle and Nuclear Physics 07/2005; · 2.26 Impact Factor 
Article: Twoscale scalar mesons in nuclei
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ABSTRACT: We generalize the linear sigma model in order to develop a chiralinvariant model of nuclear structure. The model is natural, and contains not only the usual sigma meson which is the chiral partner of the pion but also a new chiralsinglet that is responsible for the mediumrange nucleonnucleon attraction. This approach provides significant advantages in terms of its description of nuclear matter and finite nuclei in comparison with conventional models based on the linear sigma model. Comment: 12 pages, including 3 tables and 3 figures; preprint number is addedEuropean Physical Journal A 03/2005; · 2.04 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: Effect of bound nucleon internal structure change on nuclear structure functions is investigated based on local quark–hadron duality. The bound nucleon structure functions calculated for chargedlepton and (anti)neutrino scattering are all enhanced in symmetric nuclear matter at large Bjorkenx (x≳0.85) relative to those in a free nucleon. This implies that a part of the enhancement observed in the nuclear structure function F2 (in the resonance region) at large Bjorkenx (the EMC effect) is due to the effect of the bound nucleon internal structure change. However, the x dependence for the chargedlepton and (anti)neutrino scattering is different. The former (latter) is enhanced (quenched) in the region 0.8≲x≲0.9 (0.7≲x≲0.85) due to the difference of the contribution from axial vector form factor. Because of these differences charge symmetry breaking in parton distributions will be enhanced in nuclei.Physics Letters B 09/2004; · 4.57 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: Using the quarkmeson coupling model, we calculate the form factors at sigma and omeganucleon stronginteraction vertices in nuclear matter. The PeierlsYoccoz projection technique is used to take account of center of mass and recoil corrections. We also apply the Lorentz contraction to the internal quark wave function. The form factors are reduced by the nuclear medium relative to those in vacuum. At normal nuclear matter density and Q^2 = 1 GeV^2, the reduction rate in the scalar form factor is about 15%, which is almost identical to that in the vector one. We parameterize the ratios of the form factors in symmetric nuclear matter to those in vacuum as a function of nuclear density and momentum transfer.Physics Letters B 08/2003; · 4.57 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We study the effect of bound nucleon form factors on chargedcurrent neutrinonucleus scattering. The bound nucleon form factors of the vector and axialvector currents are calculated in the quarkmeson coupling model. We compute the inclusive $^{12}$C($\nu_\mu,\mu^$)$X$ cross sections using a relativistic Fermi gas model with the calculated bound nucleon form factors. The effect of the bound nucleon form factors for this reaction is a reduction of $\sim$8% for the total cross section, relative to that calculated with the free nucleon form factors. Comment: Latex, 11 pages, 3 figures, version to appear in Phys. Rev. C (Brief Report)Physical Review C 07/2003; · 3.72 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We discuss the electromagnetic form factors, axial form factors, and structure functions of a bound nucleon in the quarkmeson coupling (QMC) model. Free space nucleon form factors are calculated using the improved cloudy bag model (ICBM). After describing finite nuclei and nuclear matter in the quarkbased QMC model, we compute the inmedium modification of the bound nucleon form factors in the same framework. Finally, limits on the medium modification of the bound nucleon $F_2$ structure function are obtained using the calculated inmedium electromagnetic form factors and local quarkhadron duality.02/2003;  [Show abstract] [Hide abstract]
ABSTRACT: We study both the spinaverage and spindependent structure functions of the lithium isotopes, $^{611}$Li, which could be measured at RIKEN and other nuclear facilities in the future. It is found that the lightcone momentum distribution of the valence neutron in the halo of $^{11}$Li is very sharp and symmetric around y = 1, because of the weak binding. The EMC ratios for Li isotopes are then calculated. We study the possibility of extracting the neutron structure function from data for the nuclear structure functions of the Li isotopes. Next we calculate the spindependent structure functions of $^{7,9,11}$Li isotopes, which have spin of 3/2. The effect of the nuclear binding and Fermi motion on the multipole spin structure function, $^{3/2}_{~1}g_1$, is about 10% in the region x < 0.7, but it becomes quite important at large x. The spin structure function of $^{3/2}_{~3}g_1$ is also investigated. Finally, we discuss the modification of the Gottfried and Bjorken integrals in a nuclear medium and point out several candidates for a pair of mirror nuclei to study the flavornonsinglet quark distributions in nuclei. Comment: 23 pages + 7 tables + 15 figuresNuclear Physics A 10/2001; · 1.53 Impact Factor 
Article: Nonsinglet structure function of the^{3} He^{3} H system and divergence of the Gottfried integral
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ABSTRACT: We study shadowing and antishadowing corrections to the flavor nonsinglet structure function F23HeF23H and show that the difference between the oneparticle density distributions of 3He and 3H plays an important role at very small x. We find that the flavor nonsinglet structure function in these mirror nuclei is enhanced at small x by nuclear shadowing, which increases the nuclear Gottfried integral, integrated from 104 to 3, by 15–41 %. When integrated from zero, the Gottfried integral is divergent for these mirror nuclei. It seems likely that, as a consequence of charge symmetry breaking, this may also apply to the protonneutron system.Physical review D: Particles and fields 08/2001; 64(5). 
Article: Pions in isospin asymmetric nuclei
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ABSTRACT: Using a pair of the lightest mirror nuclei, 3He and 3H, we study the effect of the medium modification of pion fields on the flavor nonsinglet structure function. The change of the pion fields leads to an enhancement of the flavor asymmetry of the antiquark distributions in a nucleus.Physics Letters B 03/2001; · 4.57 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We study deep inelastic scattering on isospin asymmetric nuclei. In particular, the difference of the nuclear structure functions and the Gottfried sum rule for the lightest mirror nuclei, 3He and 3H, are investigated. It is found that such systems can provide significant information on charge symmetry breaking and flavor asymmetry in the nuclear medium. Furthermore, we propose a new method to extract the neutron structure function from radioactive isotopes far from the line of stability. We also discuss the flavor asymmetry in the Drell–Yan process with isospin asymmetric nuclei.Physics Letters B 08/2000; · 4.57 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We discuss the effect of changes in meson properties in a nuclear medium on physical observables, notably, $J/\Psi$ dissociation on pion and $\rho$ meson comovers in relativistic heavy ion collisions, and the prediction of the $\omega$, $\eta$ and $\eta'$nuclear bound states. Comment: 6 pages, 5 Postscript figures, uses espcrc1.sty, 2 talks given by K. Tsushima at the International Conference on Quark Nuclear Physics, Adelaide, February 2125, 2000, to be published in the Proceedings, Nucl. Phys. A05/2000;  [Show abstract] [Hide abstract]
ABSTRACT: We make a detailed study of the effect that the recently predicted modification of the inmedium masses of charmed mesons would have on J/Ψ dissociation on pion and ρmeson comovers in relativistic heavy ion collisions. We find a substantial dependence of the J/Ψ absorption rates on the density and temperature of the nuclear matter. This suggests that a quantitative analysis of J/Ψ dissociation in nucleus nucleus collisions should include the effects of the modification of meson masses in dense matter.Physics Letters B 01/2000; · 4.57 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: The binding energy differences of the valence proton and neutron of the mirror nuclei, 15O–15N, 17F–17O, 39Ca–39K and 41Sc–41Ca, are calculated using the quarkmeson coupling (QMC) model. The calculation involves nuclear structure and shell effects explicitly. It is shown that binding energy differences of a few hundred keV arise from the strong interaction, even after subtracting all electromagnetic corrections. The origin of these differences may be ascribed to the charge symmetry breaking effects set in the strong interaction through the u and d current quark mass difference.Physics Letters B 07/1999; · 4.57 Impact Factor
Publication Stats
1k  Citations  
157.40  Total Impact Points  
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Institutions

2003–2011

Tokyo University of Science
 Department of Fire Science and Technology
Edo, Tōkyō, Japan


1994–2001

University of Adelaide
 Special Research Centre for the Subatomic Structure of Matter
Adelaide, South Australia, Australia


1998

Sendai National College of Technology
Sendai, Kagoshima, Japan
