121035915
QUARKONIUM AT FINITE TEMPERATURE
We study quarkonium at finite temperature by using a hadron string model. It is shown that as the temperature is increased, the mass of the quarkonium decreases and the slope of the Regge trajectory is changed.
123223657
A Vibrational Bag Model for Baryons
Surface monopole vibration of baryons is investigated on the basis of the soliton bag model. We derive a relativistic Lagrangian for the surface motion whose mass parameter is proportional to square of the bag radius. With the use of the WKB approximation, the energy spectra of Pl1 and F" resonances are reproduced by our model fairly well. The static properties of the nucleon are alsO studied in our vibrational bag model and compared with those of the static bag model. Our model predicts that the nucleon consists of the central high·density part and the surrounding low-density part. It is also shown that our model is capable to predict the experimental data as well as the static bag model.
117897053
Shear viscosity and spectral function of the quark matter
We discuss the shear viscosity of the quark matter by using the Kubo-Mori formula. It is found that the shear viscosity is expressed in terms of the quark spectral function. If the spectral function is approximated by a modified Bright-Wigner type, the viscosity decreases as the width of the spectral function increases. We also discuss dependence of the shear viscosity on the temperature and the density.
120691222
Superconductivity of Quark Matter at Finite Temperature
121686024
Excited baryons in the MIT bag model
Abstract The Johnson-Thorn bag model which explains the rotational motion of the elongated MIT bag is extended so as to describe the longitudinal vibration along the elongated bag. Our model is a kind of string model for baryons but it reduces to the ordinary spherical MIT bag model in the ground states. It is shown that the mass spectra of the P 11 and P 33 resonances of baryons can be reproduced by the present model as well as the Regge trajectories.
25502171
Rotating Bag Model for Hadrons
The MIT bag model!) has been quite successful in reproducing the observed masses and other static properties of the low-lying hadrons. It is very important to discuss whether or not excited states of the hadrons (resonances) can be explained in the framework of the bag model. A number of excited states have been described successfully by considering collective excitations of the bag.) In particular, Johnson and Thorn) investigated a series of excited states known as the Regge trajectory by using the rotating bag model. They assumed that the rotating bag has stringlike shape with two ends by the centrifugal force and the transverse length is negligible compared with its longitudinal one. From this onedimensional bag model, they succeeded in reproducing the experimental value of the Regge slope very well. Furthermore it was showt: by Wakimaru and one of the present authors (M. I.) that this simple model can explain not only the Regge slope but also the energy spectra of the trajectories.) On the other hand, Eguchi and Migdal et aJ.5) also discussed the excited states by using their string models 'which are independent of the bag model. Any string model which has been proposed is based on the assumption that the shape is stringlike or one-dimensional. Is the assumption of the stringlike shape, however, surely true? section of the stringlike bag, which we call tube, can be given by
118375151
Enhancement of muonium emission rate from silica aerogel with a laser-ablated surface
e ) atoms from a laser-processed aerogel surface into vacuumwas studied for the rst time. Laser ablation was used to create hole-like regions withdiameter of about 270 m in a triangular pattern with hole separation in the range of300{500 m. The emission probability for the laser-processed aerogel sample is at leasteight times higher than for a uniform one.
122256238
Kaonic hydrogen X-ray experiment at KEK
Abstract For the further understanding of the K -N interaction in the low energy region, we are performing a measurement of K − p X rays at KEK which adopts a new technique to improve the signal-to-background ratio (S/N); specifying the final state of the K − p reaction and using a gaseous hydrogen target (4 atm at 100 K). With this technique three orders of magnitude better S/N and one order higher statistics are expected as compared to previous experiments.
123694791
A Search for $\phi $ Meson Nucleus Bound State Using Antiproton Annihilation on Nucleus
120551306
Experimental Search for Kaonic Nuclear Bound States in the 4He(stopped K-,n) Reaction
We made an experimental search for deeply bound kaonic nuclear states ppnK - in 4 He(stopped K - , n) reaction. The experiment is performed in September and October 2002 and the analysis is in progress. The experimental procedure and the present status of the analysis are described.
122803940
Secondary charged beam lines at the J-PARC hadron experimental hall