96475030
Note on the Improper Bogoliubov Transformation : An Example in the Many-Quark System
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
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.
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.
56000332
PROGRESS OF DESIGN STUDY OF INTERACTION REGION QUADRUPOLES FOR THE SUPER-KEKB
For KEKB upgrade, we are studying the design of the final focus quadrupoles to achieve very small β-functions at the interaction point (IP). For each beam, the final beam focusing system consists of quadrupole-doublet of the superconducting and permanent magnets. In this paper, the design progress of final focusing magnets is reported.
15085801
Search for a kaonic nuclear state via 4He(K−, N) reaction at rest
Very recently, we have performed a couple of experiments, KEK PS-E549/E570, for the detailed study of the strange tribaryon S 0(3115) obtained in KEK PS-E471. These experiments were performed to accumulate much higher statistics with improved experimental apparatus especially for the better proton spectroscopy of the 4He(stopped K −, N) reaction. In contrast to the previous proton spectrum, no narrow (∼ 20 MeV) peak structure was found either in the inclusive 4He(stopped K −, p) or in the semi-inclusive 4He(stopped K −, pX ±) reaction channel, which is equivalent to the previous E471 event trigger condition. Detailed analysis of the present data and simulation shows that the peak, corresponding to S 0(3115), has been an experimental artifact. Present analysis does not exclude the possible existence of a much wider structure. To be sensitive to such structure and for better understanding of the non-mesonic K − absorption reaction channel, detailed analysis of the data is in progress.
3183567
Measurement of the negative muon anomalous magnetic moment to 0.7 ppm.
The anomalous magnetic moment of the negative muon has been measured to a precision of 0.7 ppm (ppm) at the Brookhaven Alternating Gradient Synchrotron. This result is based on data collected in 2001, and is over an order of magnitude more precise than the previous measurement for the negative muon. The result a(mu(-))=11 659 214(8)(3) x 10(-10) (0.7 ppm), where the first uncertainty is statistical and the second is systematic, is consistent with previous measurements of the anomaly for the positive and the negative muon. The average of the measurements of the muon anomaly is a(mu)(exp)=11 659 208(6) x 10(-10) (0.5 ppm).
123447930
Evidence for a strongly bound kaonic system K ppn in the 4 He(stopped K ,n) reaction
We measured a neutron energy spectrum by means of time-of-flight (TOF) from the 4 He(K − stopped ,n) reaction by stopping negative kaons in a super-fluid helium target. A distinct peak was observed in the neutron spectrum, indicating the formation of a strongly bound kaonic system, K − ppn, with the binding energy and width, BKppn = 173 ± 4 MeV and Kppn . 25 MeV, respectively.
52413327
X-ray spectroscopy of kaonic atoms at SIDDHARTA
The X-ray measurements of kaonic atoms play an important role for understanding the low-energy QCD in the strangeness sector. The SIDDHARTA experiment studied the X-ray transitions of 4 light kaonic atoms (H, D, 3 He, and 4 He) using the DAFNE electron-positron collider at LNF (Italy). Most precise values of the shift and width of the kaonic hydrogen 1s state were determined, which have been now used as fundamental information for the low-energy K − p interaction in theoretical studies. An upper limit of the X-ray yield of kaonic deuterium was derived, important for future K − d experiments. The shifts and widths of the kaonic 3 He and 4 He 2p states were obtained, confirming the end of the "kaonic helium puzzle". In this contribution also the plans for new experiments of kaonic deuterium are being presented.