160 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
Exotic atoms and exotic nuclei
We briefly review the study of the exotic atoms and exotic nuclei, and report
recent research activities of eta-mesic nucleus and kaonic atoms in this
article.Comment: 6 pages, 2 figures. Talk given at II Symposium on applied nuclear
physics and innovative technologies, Jagiellonian University, Krakow, Poland,
Acta Physica Polonica B (2015) in pres
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
Formation of Heavy Meson Bound States by Two Nucleon Pick-up Reactions
We develop a model to evaluate the formation rate of the heavy mesic nuclei
in the two nucleon pick-up reactions, and apply it to the Li target cases
for the formation of heavy meson- bound states, as examples. The
existence of the quasi-deuteron in the target nucleus is assumed in this model.
It is found that the mesic nuclei formation in the recoilless kinematics is
possible even for heavier mesons than nucleon in the two nucleon pick-up
reactions. We find the formation rate of the meson- bound states can be
around half of the elementary cross sections at the recoilless kinematics with
small distortions.Comment: 1 table, 10 figures, 8 page
Formation spectra of light kaonic nuclei by in-flight () reactions with chiral unitary amplitude
We study theoretically the in-flight () reactions for the formation of
light kaonic nuclear systems to get deeper physical insights on the expected
spectra, and to investigate the experimental feasibility of the reaction at new
facilities like J-PARC. We show the expected spectra for the formation of the
, and -B systems which are accessible by the
() experiments. By considering the conversion part of the Green's
function, we can show the missing mass spectra of the () reactions
coincidence with the particle emissions due to absorption in processes. To calculate the cross sections, we use the so-called
approximation to evaluate the optical potential. As for the amplitude
, we adopt the chiral unitary amplitude of channel in vacuum for
simplicity, and we also check the medium effects by applying the chiral
amplitude at finite density. The effects of the p-wave optical potential of
(1385) channel and the contribution from mixing in
He() reaction are also evaluated numerically. To understand the
meanings of the spectrum shape, we also study the behavior of the poles of kaon
Green's function in nuclear matter. We conclude that He() and
He() reactions coincident with the emission due to
absorption may show the certain structure in the bound region
spectra indicating the existence of the unstable kaonic nuclear bound states.
As for the C() spectra with the emission, we may also
observe the structure in the bound region, however, we need to evaluate the
medium effects carefully for larger nuclei.Comment: 14 pages, 12 figure
The decay of the and resonances in the hidden gauge formalism
Using recent results obtained within the hidden gauge formalism for vector
mesons, in which the and resonances are dynamically
generated resonances from the interaction, we evaluate the
radiative decay of these resonances into . We obtain results for
the width in good agreement with the experimental data for the
state and a width about a factor five smaller for the resonance,
which would agree with preliminary results from the Belle collaboration,
hinting at an order of magnitude smaller width for this resonance than for the
.Comment: 7 pages, 9 figures, proof of gauge invariance adde
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