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
6081502
Mass spectra and decay widths of hadrons in the relativistic string model
A relativistic string model for hadrons is presented. The center-of-mass motion is separated correctly. The vibrational and rotational motions of the string are solved by using the WKB approximation. Moreover, their decay widths are calculated by taking into account the pair creation of quarks inside the string. Both the mass spectra and the decay widths are reproduced fairly well in comparison with experimental data.
123013869
An Application of the Glauber Approximation to High Energy Heavy-Ion Collisions. I Theoretical Formulation
10122460
First order phase transition in quark matter
We investigate chiral phase transition of the first order in the quark matter. Using the Nambu-Jona-Lasinio model, an equation of state of the quark matter which is similar to the van der Waals's one is obtained. Moreover the specific heat and the compressibility are calculated. It is shown that they are enhanced in the symmetry broken phase, in particular, diverge near the tricritical point.
16001859
Phase transition of color superconductivity and cooling behavior of quark stars
We discuss color superconductivity and its effect on the cooling behavior of strange quark stars. The neutrino emissivity and specific heat of quark matter are calculated within the BCS theory. In the superconducting phase, the emissivity decreases and causes suppression of the cooling rate. It is shown that the phase transition leads to a sudden discontinuous suppression of the cooling rate in cooperation with the specific heat.
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.
117791711
Radioactive Muonic Atom Studies with Intense Muon Beams
New intense muon beams with flux several orders of magnitude higher than at present muon facilities would allow many novel experimental studies that were until now statistically not feasible. The investigation of the nuclear properties of short‐lived nuclei using muonic atom spectroscopy would become possible. In this paper, the recent progress of a feasibility study at RIKEN‐RAL muon facility using the cold hydrogen film method to produce radioactive muonic atoms is being reported. The first experimental results have just been obtained with stable argon ions implanted in solid deuterium films.
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.
119756253
R&D status of a large-aperture hybrid avalanche photo-detector
This paper reports on the R&D status of a large-aperture Hybrid Avalanche Photo-Detector (HAPD). We have developed a 13-inch aperture HAPD and its readout system. The HAPD is a photo-detector expected to replace the photomultiplier tube (PMT) in next-generation imaging water Cherenkov detectors such as Hyper Kamiokande. We will present the recent progress made in readout system development. The readout system involves a fast sampling device. The sampling depth (number of cells) has been extended to 256 from 64 in order to measure longer waveform length. The variation in AC gain is now fixed and the input analog bandwidth improved.
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,
120900736
Kaonic nitrogen X-ray transition yields in a gaseous target
Abstract The first measurement of the yields of three kaonic nitrogen X-ray transitions, using the DEAR (DAΦNE Exotic Atom Research) setup at the DAΦNE collider of Frascati, is reported. The yields are 41.5±8.7(stat.)±4.1(sys.)% for the n =7→6 transition, 55.0±3.9(stat.)±5.5(sys.)% for the n =6→5 transition and 57.4±15.2(stat.)±5.7(sys.)% for the n =5→4 transition at a density ρ =3.4 ρ NTP . By using the experimental yields in an atomic cascade calculation, a 1 to 3% K-shell electron population in the n =6 level was deduced.