31 research outputs found
Existence of \sigma(600)/\kappa(900)-Particle and New Chiral Scalar Nonet ``Chiralons''
The \sigma(600) and \kappa(900), observed in the phase shift analyses,
satisfy rather well the mass and width relation predicted by the SU(3)LsM and
the SU(3)LsM with the vector and axial-vector meson nonets, and deserve to be
the members of scalar \sigma-nonet, together with the observed resonances
a_0(980) and f_0(980), as a chiral partner of pseudoscalar \pi-nonet. In the
phase shift analyses an introduction of repulsive background phase \delta_{BG}
is essential, whose origin has a close connection to the \lambda\phi^4
interaction in LsM. It is argued that the members of this \sigma-nonet,
"Chiralons", have different properties and should be discriminated from the
conventional ^3P_0-qqbar-scalar nonet.Comment: Talk at HADRON'97, the 7th int. conf. on hadron spectroscopy, BNL,
August 1997. 4 pages with 1 eps figur
pi^0 pi^0 Scattering Amplitudes and Phase Shifts Obtained by the pi^- P Charge Exchange Process
The results of the analysis of the pi^0 pi^0 scattering amplitudes obtained
with pi^- P charge exchange reaction, pi^- P --> pi^0 pi^0 n, data at 9 GeV/c
are presented. The pi^0 pi^0 scattering amplitudes show clear f_0(1370) and
f_2(1270) signals in the S and D waves, respectively. The pi^0 pi^0 scattering
phase shifts have been obtained below Kbar K threshold and been analyzed by the
Interfering Amplitude method with introduction of negative background phases.
The results show a S wave resonance, sigma. Its Breit-Wigner parameters are in
good agreement with those of our previous analysis on the pi^+ pi^- phase shift
data.Comment: 4 pages, 4 figures. Proceedings of the int. conf. Hadron'99 at
Beijing, Aug. 1999. Presented for the collaboration of A.M.Ma, K.Takamatsu,
M.Y.Ishida, S.Ishida, T.Ishida, T. Tsuru and H. Shimizu, and the E135
collaboration. For our activities on sigma, visit
http://amaterasu.kek.jp/sigm
Triplet superconductivity in a one-dimensional ferromagnetic t-J model
In this paper we study the ground state phase diagram of a one-dimensional
model, at half-filling. In the large-bandwidth limit and for
ferromagnetic exchange with easy-plane anisotropy, a phase with gapless charge
and massive spin excitations, characterized by the coexistence of triplet
superconducting () and spin density wave () instabilities is
realized in the ground state. With reduction of the bandwidth, a transition
into an insulating phase showing properties of the spin-1/2 XY model takes
place. In the case of weakly anisotropic antiferromagnetic exchange the system
shows a long range dimerized (Peierls) ordering in the ground state. The
complete weak-coupling phase diagram of the model, including effects of the
on-site Hubbard interaction, is obtained
Possible origins of macroscopic left-right asymmetry in organisms
I consider the microscopic mechanisms by which a particular left-right (L/R)
asymmetry is generated at the organism level from the microscopic handedness of
cytoskeletal molecules. In light of a fundamental symmetry principle, the
typical pattern-formation mechanisms of diffusion plus regulation cannot
implement the "right-hand rule"; at the microscopic level, the cell's
cytoskeleton of chiral filaments seems always to be involved, usually in
collective states driven by polymerization forces or molecular motors. It seems
particularly easy for handedness to emerge in a shear or rotation in the
background of an effectively two-dimensional system, such as the cell membrane
or a layer of cells, as this requires no pre-existing axis apart from the layer
normal. I detail a scenario involving actin/myosin layers in snails and in C.
elegans, and also one about the microtubule layer in plant cells. I also survey
the other examples that I am aware of, such as the emergence of handedness such
as the emergence of handedness in neurons, in eukaryote cell motility, and in
non-flagellated bacteria.Comment: 42 pages, 6 figures, resubmitted to J. Stat. Phys. special issue.
Major rewrite, rearranged sections/subsections, new Fig 3 + 6, new physics in
Sec 2.4 and 3.4.1, added Sec 5 and subsections of Sec
Measurement of single pi0 production in neutral current neutrino interactions with water by a 1.3 GeV wide band muon neutrino beam
Neutral current single pi0 production induced by neutrinos with a mean energy
of 1.3 GeV is measured at a 1000 ton water Cherenkov detector as a near
detector of the K2K long baseline neutrino experiment. The cross section for
this process relative to the total charged current cross section is measured to
be 0.064 +- 0.001 (stat.) +- 0.007 (sys.). The momentum distribution of
produced pi0s is measured and is found to be in good agreement with an
expectation from the present knowledge of the neutrino cross sections.Comment: 6 pages, 4 figures, Submitted to Phys. Lett.
Evidence for muon neutrino oscillation in an accelerator-based experiment
We present results for muon neutrino oscillation in the KEK to Kamioka (K2K)
long-baseline neutrino oscillation experiment. K2K uses an accelerator-produced
muon neutrino beam with a mean energy of 1.3 GeV directed at the
Super-Kamiokande detector. We observed the energy dependent disappearance of
muon neutrino, which we presume have oscillated to tau neutrino. The
probability that we would observe these results if there is no neutrino
oscillation is 0.0050% (4.0 sigma).Comment: 5 pages, 4 figure
The pole in
Using a sample of 58 million events recorded in the BESII detector,
the decay is studied. There are conspicuous
and signals. At low mass, a large
broad peak due to the is observed, and its pole position is determined
to be - MeV from the mean of six analyses.
The errors are dominated by the systematic errors.Comment: 15 pages, 6 figures, submitted to PL
Construction status and prospects of the Hyper-Kamiokande project
The Hyper-Kamiokande project is a 258-kton Water Cherenkov together with a 1.3-MW high-intensity neutrino beam from the Japan Proton Accelerator Research Complex (J-PARC). The inner detector with 186-kton fiducial volume is viewed by 20-inch photomultiplier tubes (PMTs) and multi-PMT modules, and thereby provides state-of-the-art of Cherenkov ring reconstruction with thresholds in the range of few MeVs. The project is expected to lead to precision neutrino oscillation studies, especially neutrino CP violation, nucleon decay searches, and low energy neutrino astronomy. In 2020, the project was officially approved and construction of the far detector was started at Kamioka. In 2021, the excavation of the access tunnel and initial mass production of the newly developed 20-inch PMTs was also started. In this paper, we present a basic overview of the project and the latest updates on the construction status of the project, which is expected to commence operation in 2027
Prospects for neutrino astrophysics with Hyper-Kamiokande
Hyper-Kamiokande is a multi-purpose next generation neutrino experiment. The detector is a two-layered cylindrical shape ultra-pure water tank, with its height of 64 m and diameter of 71 m. The inner detector will be surrounded by tens of thousands of twenty-inch photosensors and multi-PMT modules to detect water Cherenkov radiation due to the charged particles and provide our fiducial volume of 188 kt. This detection technique is established by Kamiokande and Super-Kamiokande. As the successor of these experiments, Hyper-K will be located deep underground, 600 m below Mt. Tochibora at Kamioka in Japan to reduce cosmic-ray backgrounds. Besides our physics program with accelerator neutrino, atmospheric neutrino and proton decay, neutrino astrophysics is an important research topic for Hyper-K. With its fruitful physics research programs, Hyper-K will play a critical role in the next neutrino physics frontier. It will also provide important information via astrophysical neutrino measurements, i.e., solar neutrino, supernova burst neutrinos and supernova relic neutrino. Here, we will discuss the physics potential of Hyper-K neutrino astrophysics