1,643,930 research outputs found
Interference phenomena in the decay induced by the mixing
Using the data on the decay , we
estimate the amplitude of the process , caused by the
mixing of and resonances that breaks the isotopic
invariance due to the and meson mass difference. Effects of the
interference of this amplitude with the amplitudes of the main mechanisms
responsible for the decay are analyzed. As such
mechanisms, we examine the transition ,
which is observed in experiment, and the possible transition
. It
is shown that the rapidly varying phase of the transition
amplitude strongly influences on the interference curves.Comment: 7 pages, 7 figures; v2, replaced with the published version; typos
corrected, clarifications and reference adde
Two-Photon Production of Four-Quark States Up to the Energy
Evidence for an explicitly exotic state with isospin 2 and spin-parity 2^+
near the threshold and nontrivial complementary indications of the
unusual quark composition of the and states obtained from
the reactions of two-photon formation of neutral meson resonances are
discussed, together with puzzling phenomena in the channels
and at high energies.Comment: RevTex, 5 pages and one PS figure. Talk presented by G.N. Shestakov
at the International Workshop on e^+e^- Collisions from to ,
Budker Institute of Nuclear Physics, Novosibiksk, Russia, March 1-5, 199
A Universal Model for Bingham Fluids with Two Characteristic Yield Stresses
We inroduce a new model for Bingham fluids with a complicated dependence of
the deformation velocity on the shear stress. Specific features of the flow
rate for such fluid are studied. This model embraces many special and limiting
cases, for many of them analytic calculations become possibleComment: 6 pages, 1 figur
Description of the \psi(3770) resonance interfering with the background
The parameters of the interfering resonance should be determined
from the data on the reactions \,\, with the use of the
models satisfying the elastic unitarity requirement. The selection of such
models can be realized by comparing their predictions with the relevant data on
the shape of the peak in the non- decay channels. Here,
we illustrate this unitarity approach by the example of the most simple variant
of the model of the mixed and resonances. When new
high-statistics data become available, it will be interesting to test this
clarity variant.Comment: 5 pages, 4 figures; v2: matches published version in Phys. Rev.
Proposal to look for the anomalous isotopic symmetry breaking in central diffractive production of the and resonances at the LHC
At very high energies, and in the central region (), the
double-Pomeron exchange mechanism gives the dominant contribution to the
production of hadrons with the positive parity and isospin .
Therefore, the observation of resonances in the states with will be
indicative of their production or decay with the isotopic symmetry breaking.
Here, we bear in mind the cases of the anomalous breaking of the isotopic
symmetry, i.e., when the cross section of the process breaking the isospin is
not of the order of of the cross section of the allowed process but
of the order of . The paper draws attention to the reactions and in which a similar situation can be realized,
owing to the loop mechanisms of the breaking of isotopic symmetry. We
note that there is no visible background in the and channels. Observation of the process would be a confirmation of the first results from the VES
and BESIII detectors, indicating the very large isospin breaking in the decay
.Comment: 5 pages, 4 figures; v2: title changed, comments and references adde
Mechanisms of the Reaction at High Energies
Over the last twenty years, it was assumed that the reaction at high energies is dominated by Regge pole
exchange. We show that the new Brookhaven and Serpukhov data on the
distributions for this reaction can be explained within the framework of the
Regge pole model only if the Regge pole exchange conspiring with its
daughter plays a crucial role. The tentative estimates of the absolute
reaction cross section are obtained. The
contributions of the one-pion exchange mechanism and the Regge cuts are also
estimated.Comment: Talk given at HADRON'9
Nature of Light Scalar Mesons in Bright Light of Photon-Photon Collisions
The surprising thing is that the light scalar meson problem, arising 50 years
ago from the linear sigma model (LSM) with spontaneously broken chiral
symmetry, has become central in the nonperturbative quantum chromodynamics
(QCD), because it has been made clear that LSM could be the low energy
realization of QCD. First, we review briefly signs of four-quark nature of
light scalars. Then we show that the light scalars are produced in the
two-photon collisions via four-quark transitions in contrast to the classic P
wave tensor q\bar q mesons that are produced via two-quark transitions
\gamma\gamma->q\bar q. Thus we get new evidence of the four-quark nature of the
lower scalar states.Comment: 8 pages, 14 figures. The talk given by G.N. Shestakov at the
International Seminar "Quarks-2010", Kolomna, Russia, June 6-12, 201
Manifestations of the mixing in and decays
Possible manifestations of the isospin-breaking mixing of the
and resonances are analyzed in the and
decays. It is shown that the
mixing has the most influence on the mass spectrum in the decay
. Owing to the mixing, the
peak in can experience
distortions comparable with its size. The effect essentially depends on the
relative phase between the amplitudes of the and transitions.Comment: 7 pages, 2 figures; v2: replaced with the published version; typos
corrected, clarifications and reference adde
Effective Lagrangians Induced by the Anomalous Wess-Zumino Action and Exotic States
A simple dynamical model for the exotic waves with
in the reactions , ,
, , and in the related
ones, is constructed beyond the scope of the quark-gluon approach. The model
satisfies unitarity and analyticity and uses as a "priming" the anomalous
non-diagonal interaction which couples together the four channels
, , , and . The possibility
of the resonance-like behavior of the amplitudes
belonging to the and representations of SU(3) as
well as their mixing is demonstrated explicitly in the 1.3--1.6 GeV mass range
which, according to the current experiments, is really rich in exotics.Comment: Parallel session talk given at HADRON 2001, Protvino, Russia, August
28, 2001. LaTex, 5 pages, 1 figur
f0(980) and a0(980) resonances near \gamma\gamma\to K^+K^- and \gamma\gamma\to K^0\bar K^0 reaction thresholds
High-statistics data on the reactions and
are the last missing link in investigations of
the light scalar mesons and in photon-photon collisions.
It is believed that and resonances exhibit their
four-quark structure in these reactions in a vary peculiar way. The work
estimates the feasibility of measurements of scalar contributions near
and reaction thresholds
at modern colliders.Comment: 3 pages, 1 figure, accepted in JETP Letter
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