9987198
Measurement of the kaonic hydrogen x-ray spectrum.
The DEAR (DAPhiNE exotic atom research) experiment measured the energy of x rays emitted in the transitions to the ground state of kaonic hydrogen. The measured values for the shift epsilon and the width Gamma of the 1s state due to the K(-)p strong interaction are epsilon(1s)=-193 +/- 37 (stat) +/- 6 (syst) eV and Gamma(1s)=249 +/- 111 (stat) +/- 30 (syst) eV, the most precise values yet obtained. The pattern of the kaonic hydrogen K-series lines, K(alpha), K(beta), and K(gamma), was disentangled for the first time.
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.
122600834
Muon catalyzed fusion experiments on muonic deuterium atom deceleration in thin solid deuterium films
Abstract Muon catalyzed fusion was investigated in a series of thin solid deuterium films by detecting protons from dd fusion. Two different contributions to the total fusion yield resulting from dμ atoms emitted from a primary hydrogen layer and from incident muons directly stopped in the deuterium film itself were observed. The thickness dependence of the fusion yield suggested the importance of molecular effects in dμ elastic scattering in D 2 .
124123633
SEARCH FOR LORENTZ AND CPT VIOLATION EFFECTS IN MUON SPIN PRECESSION
124815658
Measure of the spatial size for the monopole excitation in proton scattering
121882195
Discovery of the repulsive energy shift of the kaonic hydrogen 1s state
Abstract The aim in this manuscript is to clarify the progress in understanding the nature of the K ¯ N interaction at the lowest energy, given by the recent kaonic hydrogen X-ray experiment at KEK [1]. We have observed a clear spectrum showing the kaonic hydrogen K α line, for the first time. The analysis gives the repulsive energy shift to be Δ E (1 s ) = −323 ± 63(statistical) ± 11 (systematic) eV and the energy width to be Λ(1 s ) = 407 ± 208 ± 100 eV. This result is consistent with analyses of the previous low-energy scattering data and resolves the long-standing kaonic hydrogen puzzle.
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.
125753081
Magnetic Field Measurement System for the SuperKEKB Final Focus Superconducting Magnets
SuperKEKB final beam focusing system consists of different types of superconducting magnets: 8 quadrupole magnets, 4 solenoids and 43 corrector coils. In order to measure the field performances of the magnets and the coils, KEK prepared one set of harmonic coil system during the production stage in a factory, and two sets of harmonic coil systems for the cold tests at 4K for the vertical cryostat test stand in KEK. In this paper, we report these magnetic field measurement systems
120221589
Hartree-Bogoliubov Theory of Quark Matter: Condensation Energy in Strange Quark Matter
73685731
Flux tube model for glueballs
We calculate the mass spectra and decay widths of glueballs in the flux tube model. The glueball is assumed to be a flux tube ring. The breathing and the rotational motions are investigated using the WKB approximation. The calculated spectrum is consistent with those obtained by lattice QCD. The decay widths are also computed using the Schwinger mechanism, and it is shown that they have rather large values. It is widely believed that the strong interaction is de- scribed by quantum chromodynamics ~QCD !@ 1#. It is, how- ever, very difficult to solve QCD, so that several effective models have been devised to explain the physical properties of many hadrons. The flux tube model @2#, or hadron string model @3,4#, is one such model. According to this model, mesons are made up of a quark and antiquark connected by a color flux tube and baryons are described by a quark and diquark connected by the same flux tube. We showed in a previous paper @5# that various excited states of the hadrons can be explained systematically using such a simple model. On the other hand, recent lattice QCD simulations @6# predict the existence of glueballs, which are composed of only gluons. It is the purpose of this paper to present an intuitive and analytic approach to glueballs using a flux tube model. We assume that the glueball is a closed color flux tube ~flux tube ring !. Moreover, the flux tube that constitutes the ring is assumed to have the same properties as the flux tube that constitutes a meson or a baryon. Consequently, our model has no free parameter. We study the relativistic motion of the closed string and obtain the mass spectrum of the glueballs. This simple picture has already been considered by several authors. In particular, Koma, Suganuma, and Toki @7# studied the relativistic breathing motion analytically with the use of the dual Ginzburg-Landau theory @ 8-1 0#. We study not only the vibrational motion but also the rotational one. Moreover, the decay widths in @7# are also calculated by taking into account qqpair production inside the flux tube ~Schwinger mechanism!. This paper is organized as follows. In the next section, the flux tube model for the glueballs is formulated. Section III is devoted to calculation of the mass spectra and the decay widths of the glueballs. In Sec. IV, the numerical results are presented and some discussion is given.
123025217
Pairing Correlation in Quark Matter
The superconductivity in quark matter is investigated by a generalized mean field approximation. If we assume that two quarks interact each other via the one·gluon exchange potential, attractive force appears in the color·triplet and spin-parallel state. Applying a BCS-like theory to the system, it is shown that we obtain a new superconducting state which is more stable than the normal (Fermi gas) state. We also give the explicit expression of the superconducting state. Recently the possibility of strange quark matter1> has been studied by many authors by using various effective models for QCD. In these approaches2> they have supposed that the ground state of the quark matter is a degenerate Fermi gas state where each quark occupies a single-particle state with definite momentum under the Fermi momentum. We think that this assumption is not so evident. If the interac­ tion between two quarks is attractive and strong enough, the ground state would become a correlated state just like the BCS state in the superconductors rather than the normal state (the Fermi gas state). We will investigate this possibility in this paper. There are several approaches3>.4> to take into account such pairing correlations. They are restricted to the SU(2) quark matter because any two-quark system has color necessarily. In the SU(3), we note that there are three kinds of quark pairs which bear the same color as three kinds of anti-quarks. If such three quark pairs condense in the same way, there may exist a new boson condensate which is a color-singlet state. It is the purpose of this note to discuss such possibility, the color SU(3) superconductivity in the quark matter, by using a mean field approximation. § 2. Attractive force between two quarks First let us consider possibility of appearance of the attractive force between two quarks. We assume the one-gluon exchange potential,5>