123071679
Regge trajectories of baryons in the MIT bag model
Abstract We investigate Regge trajectories of baryons in the MIT bag model. It is shown that the energy spectra shown by the trajectories can be described fairly well by the stringlike solutions of the bag model. In particular, three strings with one junction and three ends can explain the delta trajectory better than one string with two ends. The three ends occupied by each quark are assumed to be an equilateral triangle configuration in our calculations.
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.
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.
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.
120691222
Superconductivity of Quark Matter at Finite Temperature
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
110271540
Compact 8-lead unit for the SC correction coils of the SuperKEKB IR magnet system
In the proposed SuperKEKB interaction region (IR) magnet system 40superconducting (SC) correction coils are designed to perform some specific functions withcurrent of about 50 A. To energize these coils, 80 current leads will be mounted in thecryostats where the stringent spatial constraint and the cryogenic operation require acompact and optimum design. We propose a compact unit to integrate 8 helium vaporcooled leads (4 pairs). The 8 leads are made of brass and consist of two structures for thetransported current and helium vapor, which are designed and simulated by finite elementmodel (FEM). This paper will introduce the material selection and structure details. To equalize the temperature profiles of the individual leads under the different currents and helium flows, some copper blocks are placed between leads. In the cold test, the 8 leadswere operated in the nominal mode and responded safely to some transient situation. This paper will present the thermal and electrical comparison between the experi...
103405849
Kaonic Atoms Experimental Studies At Dafne
122785400
Search for Heavy Neutrinos in Kaon Decay
We obtained a new constraint of | u . 1 * * versus m(v.), as shown in Fig.l. Because or the better resolution the lower end of the neutrino mass was reduced to 40 MeV. In Fig.l are also shown other upper limits. One is from R -» j/v done /3/ at SIN. Another comes from the 1 He(jf ,v ) reaction /4/. 1 For the first time we obtained e + spectrum with rejection of the three body decay mode. Hitherto only the e v peak region of 247 MeV/c was known /$/. From the analysis oj; the spectrum we obtained a new constraint, on I U | in a wide mass range between 140 and 350 MeV, as shown in Fig.2. The JL* -> e y experiment /6/ at TRIUMF covers a complementary mass region. A recent experiment to search for neutrino0decays at CERN /?/ gave a new constraint on |U | but the present experiment has yielded a one-order of magnitude better constraint. It should be noted that the deduction of | l I e i l from the CERN experiment requires a model for heavy neutrino decay, while in the present experiment it is given purely kmematically,
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.
120897225
L-series X-ray yields of kaonic 3He and 4He atoms in gaseous targets
The SIDDHARTA experiment measured X-rays from kaonic helium atoms using, for the first time, gaseous 3He and 4He targets. Clear patterns of the L-series X-rays of kaonic 3He and 4He atoms were observed. By using accurate Monte Carlo simulations, the absolute yields of these X-ray transitions were determined to be Y(3d → 2p) = 25.0−5.8+6.7% for 3He (0.96 g/l), Y(3d → 2p) = 23.1−4.2+6.0% for 4He (1.65 g/l), and Y(3d → 2p) = 17.2−9.5+2.6% for 4He (2.15g/l). In addition, the yields Y (nd → 2p), with n > 3 were also determined. The measured yields provide valuable information for understanding the cascade processes of kaonic helium atoms as a function of the target density.