30324227
Towards a microscopic understanding of nuclear structure functions.
It has recently been shown that the twist-two valence quark distributions calculated in the MIT bag model are in reasonable agreement with world data. Furthermore, several authors have constructed mean-field theories which reproduce the saturation properties of nuclear matter in terms of a mean-field theory of nonoverlapping bags, self-consistently bound by scalar and vector meson exchange. By using a local density approximation we combine these developments to microscopically investigate the structure functions of finite nuclei. Not only do we obtain a semiquantitative description of the data (the so-called European Muon Collaboration effect) but we also show that the conventional treatment based on nucleon binding is quantitatively unreliable.
10938062
Composite nucleons in scalar and vector mean fields.
We emphasize that the composite structure of the nucleon may play quite an important role in nuclear physics. It is shown that the momentum-dependent repulsive force of second order in the scalar field, which plays an important role in Dirac phenomenology, can be found in the quark-meson coupling (QMC) model, and that the properties of nuclear matter are well described through the quark-scalar density in a nucleon and a self-consistency condition for the scalar field. The difference between theories of pointlike nucleons and composite ones may be seen in the change of the {omega}-meson mass in nuclear matter if the composite nature of the nucleon suppresses contributions from nucleon-antinucleon pair creation.
121131573
New Scaling Phenomena in Nuclear Structure Functions
We consider the nuclear mass-number (A) dependence of the nuclear structure functions. We restrict ourselves to a two-component model, in which we assume the existence of an exotic component other than the normal nucleon component in nuclei. We find that there exist scaling phenomena and that the structure function of the exotic component should be independent of A. We also show that the A dependence of the nuclear structure function can be attributed to that of the surface-to-volume ratio which is incorporated in the probability of finding the exotic component in the nucleus.
119311709
A new molecular dynamics calculation and its application to the spectra of light and strange baryons
A new approach based on antisymmetrized molecular dynamics is proposed to correctly take account of the many-body correlations. We applied it to the spectra of low-lying, light and strange baryons. The inclusion of the quark–quark correlation is important to predict the precise spectra, and the semi- relativistic kinematics is also vital to correct the level ordering. The baryon spectra calculated by the present method is as precise as the Faddeev calculation.
15022310
A Deformable Bag Model of Hadrons. I
As a generalization of the MIT spherical bag model, we construct the spheroidal bag model of hadron with an arbitrary eccentricity. This generalization is made by slightly modifying the MIT linear boundary condition: The linear boundary condition is examined in detail. Our model always satisfies two necessary requirements of the MIT bag model --i. e., n-j=O, no quark colour flux leaves the bag, and ijq =0, the scalar density of quark should vanish on the bag surface-- and it reduces to the MIT spherical bag model in the limit of zero-eccentricity. Lagrangian formalism of our model is briefly described. The eigenfrequencies of a single massless quark confined in this spheroidal bag are numer­ ically calculated. We obtain the level-splitting of the excited quark orbits, which is just analogous to the well-known Nilsson's splitting of single particle orbits in deformed nuclei. By using the numerical results of the lowest orbit, the effect of the bag-deformation on the mass of low-lying hadrons is estimated. It is found that, although the spherical bag is stable, tbe quark bag is extremely soft against the quadrupole deformation. Brief discussions are added on the mechanisms which make the spherical bag more stable.
119162077
The quark-meson coupling model and chiral symmetry
We extend the quark‐meson coupling (QMC) model to incorporate chiral symmetry. The relationship between the QMC model and chiral perturbation theory is also discussed. The nuclear central potential is modified by the effect of internal structure of the nucleon.
55538978
HIGH GRADIENT BEHAVIORS OF LARGE GRAIN ICHIRO SINGLE CELL CAVITY BY CHEMICAL POLISHING
We have started high gradient R&D with the combination of ICHIRO shape, sliced large grain niobium, and buffered chemical polishing (BCP). We fabricated one large grain ICHIRO single cell cavity that had end cell shape of ICHIRO 9-cell but no end group. We processed this cavity surface by centrifugal barrel polishing (CBP) and BCP. This cavity successfully achieved the high gradient of 42MV/m at the first vertical test. We made series test by repeating BCP on this cavity. The results of the series test will be reported. INTRODUCTION Large grain niobium SRF cavities have been developed in many laboratories, Jlab, DESY, IHEP, KEK, and so on. Our KEK LL group made breakthrough of LG Nb sheet production in 2008 [1]. We have successfully developed the multi-wire slicing method for niobium ingots with 270mm diameter collaborating with KEK, Tokyo Denkai Co. Ltd., TKX Co.Ltd., and Toyo Advanced Technologies Co. Ltd. This technology can reduce the cost of Nb sheet productions. LG cavity also can achieve high gradient of 40MV/m by BCP, not by electro polishing (EP) [2]. In order to make the breakthrough of ILC cavity cost, we are proposing the combination of sliced LG Nb materials + ICHIRO shape + BCP. This could promise the cheap, easy, and high reliable performance cavity production. In this paper, we will describe about our R&D on LG single cell cavity made of sliced Nb sheets.
45254853
Lattice thermodynamics for gauge theories.
We study the Stefan-Boltzmann formula for a free-gluon gas system in the lattice-regularized thermodynamics, and find that there arises a clear ''Debye effect'' above the temperature T/sub D/ = 1/a/sub sigma/ (a/sub sigma/ being the lattice spacing) and the Stefan-Boltzmann formula deviates from the conventional one in the high-temperature region T>T/sub D/.