12,377 research outputs found
Studies of exotic hadrons by high-energy exclusive reactions
We investigate the possibility of clarifying internal structure of exotic
hadrons by high-energy exclusive reactions. In particular, the
constituent-counting rule could be used for determining the internal
configuration in large-angle exclusive scattering. As an example, we show the
cross section pi^- + p -> K^0 + Lambda(1405) in comparison with the one for the
ground-state Lambda production pi^- + p -> K^0 + Lambda. The counting rule
indicates that the cross section scales as s^8 dsigma /dt=constant if
Lambda(1405) is an ordinary three-quark baryon, whereas it is s^{10} dsigma
/dt=constant if Lambda(1405) is a five-quark baryon. Here, s and t are
Mandelstam variables. Such experiments could be possible at J-PARC, LEP, JLab,
CERN-COMPASS, and other high-energy facilities.Comment: 4 pages, 7 figures, 12th Asia Pacific Physics Conference (APPC12),
JPS Conference Proceedings in pres
Internal structure of exotic hadrons by high-energy exclusive reactions
We propose to use high-energy exclusive reactions for probing internal
structure of exotic hadron candidates. First, the constituent counting rule of
perturbative QCD can be used for finding internal configurations of an exotic
hadron candidate. It is because the number of constituents (), which
participate in the exclusive reaction, is found by the scaling behavior of the
cross section at large momentum transfer, where
is the center-of-mass energy squared. As an example, we show that the
internal structure of should be found, for example, by the
reaction . Second, the internal structure
of exotic hadron candidates should be investigated by hadron tomography with
generalized parton distributions (GPDs) and generalized distribution amplitudes
(GDAs) in exclusive reactions. Exotic nature should be reflected in the GPDs
which contain two factors, longitudinal parton distributions as indicated by
the constituent counting rule and transverse form factors as suggested by the
hadron size. The GDAs should be investigated by the two-photon process
, for example or , in
electron-positron annihilation. Since the GDAs contain information on a
time-like form factor, exotic nature should be found by studying the
invariant mass dependence of the cross section. The internal structure of
exotic hadron candidates should be clarified by the exclusive reactions at
facilities such as J-PARC and KEKB.Comment: 6 pages, LaTeX, 9 eps files, JPS Conference Proceedings of the 2nd
International Symposium on Science at J-PARC (J-PARC 2014), Tsukuba, Japan,
July 12-15, 201
Vortex-induced topological transition of the bilinear-biquadratic Heisenberg antiferromagnet on the triangular lattice
The ordering of the classical Heisenberg antiferromagnet on the triangular
lattice with the the bilinear-biquadratic interaction is studied by Monte Carlo
simulations. It is shown that the model exhibits a topological phase transition
at a finite-temperature driven by topologically stable vortices, while the spin
correlation length remains finite even at and below the transition point. The
relevant vortices could be of three different types, depending on the value of
the biquadratic coupling. Implications to recent experiments on the triangular
antiferromagnet NiGaS is discussed
First-Order Transition to Incommensurate Phase with Broken Lattice Rotation Symmetry in Frustrated Heisenberg Model
We study a finite-temperature phase transition in the two-dimensional
classical Heisenberg model on a triangular lattice with a ferromagnetic
nearest-neighbor interaction and an antiferromagnetic
third-nearest-neighbor interaction using a Monte Carlo method. Apart from
a trivial degeneracy corresponding to O(3) spin rotations,the ground state for
has a threefold degeneracy corresponding to 120 degree lattice
rotations. We find that this model exhibits a first-order phase transition with
the breaking of the threefold symmetry when the interaction ratio is
.Comment: 4pages,5figure
Ordering of the Heisenberg spin glass in two dimensions
The spin and the chirality orderings of the Heisenberg spin glass in two
dimensions with the nearest-neighbor Gaussian coupling are investigated by
equilibrium Monte Carlo simulations. Particular attention is paid to the
behavior of the spin and the chirality correlation lengths. In order to observe
the true asymptotic behavior, fairly large system size L\gsim 20 (L the linear
dimension of the system) appears to be necessary. It is found that both the
spin and the chirality order only at zero temperature. At high temperatures,
the chiral correlation length stays shorter than spin correlation length,
whereas at lower temperatures below the crossover temperature T_\times, the
chiral correlation length exceeds the spin correlation length. The spin and the
chirality correlation-length exponents are estimated above T_\times to be
\nu_SG=0.9+-0.2 and \nu_CG=2.1+-0.3, respectively. These values are close to
the previous estimates on the basis of the domain-wall-energy calculation.
Discussion is given about the asymptotic critical behavior realized below
T_\times.Comment: to appear in a special issue of J. Phys.
Development of displacement- and frequency-noise-free interferometer in 3-D configuration for gravitational wave detection
The displacement- and frequency-noise-free interferometer (DFI) is a multiple
laser interferometer array for gravitational wave detection free from both the
displacement noise of optics and laser frequency noise. So far, partial
experimental demonstrations of DFI have been done in 2-D table top experiments.
In this paper, we report the complete demonstration of a 3-D DFI. The DFI
consists of four Mach-Zehnder interferometers with four mirrors and two
beamsplitters. The displacement noises both of mirrors and beamsplitters were
suppressed by up to 40 dB. The non-vanishing DFI response to a gravitational
wave was successfully confirmed using multiple electro-optic modulators and
computing methods
Exotic-Hadron Signature by Constituent-Counting Rule in Perturbative QCD
We explain a method to find internal quark configurations of exotic hadron
candidates by using the constituent counting rule. The counting rule was
theoretically predicted in perturbative QCD for hard exclusive hadron
reactions, and it has been tested in experiments for stable hadrons including
compound systems of hadrons such as the deuteron, H, and He. It
indicates that the cross section scales as , where
is the center-of-mass energy squared and is the total number of
constituents. We apply this method for finding internal configurations of
exotic hadron candidates, especially . There is a possibility
that could be five-quark state or a molecule, and
scaling properties should be different between the ordinary three-quark state
or five-quark one. We predict such a difference in , and it could be experimentally tested, for example, at J-PARC. On the
other hand, there are already measurements for as well as the ground in photoproduction reactions. Analyzing
such data, we found an interesting indication that looks like
a five-quark state at medium energies and a three-quark one at high energies.
However, accurate higher-energy measurements are necessary for drawing a solid
conclusion, and it should be done at JLab by using the updated 12 GeV electron
beam. Furthermore, we discuss studies of exotic hadron candidates, such as and , in electron-positron annihilation by using generalized
distribution amplitudes and the counting rule. These studies should be possible
as a KEKB experiment.Comment: 6 pages, LaTeX, 10 eps files, to be published in JPS Conf. Proc.,
Proceedings of the 14th International Conference on Meson-Nucleon Physics and
the Structure of the Nucleon (MENU2016), July 25-30, 2016, Kyoto, Japa
- …