940 research outputs found
Higher Order Two Step Mechanisms in Nucleon Antinucleon Annihilation and the OZI Rule
We evaluate three meson doorway mechanisms for nucleon-antinucleon
annihilation at rest for the first time. Detailed results are presented for the
final state phi pi0 originating from the 3S1 initial state and for the phi rho
channel originating from 1S0. The results presented also include the improved
contributions from two meson doorway states and from the tree diagrams. For all
the channels considered a consistent explanation of large and small OZI
violations emerges.Comment: 18 pages, 2 PostScript figures, will be published in Eur. Phys. J.
OZI Rule Violation in p pbar Annihilation into phi pi pi by Two Step Processes
The phi pi+ pi- production in p pbar annihilation at rest is strongly
enhanced by a two step mechanism with intermediate K Kbar pi pi states. The
relative yield of the phi production due to the resonant final state
interaction decreases with increasing total energy of the p pbar system.Comment: 18 pages, 9 PostScript figure
The effect of hidden color channels on nucleon-nucleon interaction in quark model
In the framework of constituent quark model, the effect of hidden color
channels on the nucleon-nucleon () interaction is studied. By adjusting the
color confinement strength between the hidden color channels and color singlet
channels and/or between the hidden color channels and hidden color channels,
the experimental data of to partial-wave phase shifts of
scattering can be fitted well. The results show that the hidden color channel
coupling might be important in producing the intermediate-range attraction of
interaction. The deuteron properties and dibaryon candidates have also
been studied with this model.Comment: 11 pages, 9 figure
On the relationship of the scaled phase space and Skyrme-coherent state treatments of proton antiproton annihilation at rest
We discuss pion multiplicities and single pion momentum spectra from proton
antiproton annihilation at rest. Both the scaled phase space model and the
Skyrme-coherent state approach describe these observables well. In the coherent
state approach the puzzling size of the scale parameter relating the phase
space integrals for different multiplicities is replaced by a well defined
weight function. The strength of this function is determined by the intensity
of the classical pion field and its spatial extent is of order 1 fm.Comment: 11 pages including 4 figures(postscript
Coherent Pion Radiation From Nucleon Antinucleon Annihilation
A unified picture of nucleon antinucleon annihilation into pions emerges from
a classical description of the pion wave produced in annihilation and the
subsequent quantization of that wave as a coherent state. When the constraints
of energy-momentum and iso-spin conservation are imposed on the coherent state,
the pion number distribution and charge ratios are found to be in excellent
agreement with experiment.Comment: LaTex, 8 text pages, 1 PostScript figure, PSI-PR-93-2
Structure of f0(980) from a Coupled Channel Analysis of S-wave pi pi Scattering
A coupled channel model is used to study the nature of the f0(980) resonance.
It is shown that the existence of two poles close to KKbar threshold, as found
in many data fits and confirmed here, can be reconciled with the KKbar
molecular origin of the f0(980). Due to a strong coupling between channels the
number of the S-matrix poles close to the physical region in the physical case
exceeds the number of bare states introduced in the model.Comment: 18 pages, 14 figures, published in Eur. Phys. J. C (online: February
20, 1998). The problem is more fully explored in the updated version: the
model includes the direct coupling of qqbar channel to both pipi and KKbar
channels, three new figures are added, and two data fits showing different
possibilities of the interaction between the KKbar and qqbar states are
presented and discusse
Universal Scaling of Wave Propagation Failure in Arrays of Coupled Nonlinear Cells
We study the onset of the propagation failure of wave fronts in systems of
coupled cells. We introduce a new method to analyze the scaling of the critical
external field at which fronts cease to propagate, as a function of
intercellular coupling. We find the universal scaling of the field throughout
the range of couplings, and show that the field becomes exponentially small for
large couplings. Our method is generic and applicable to a wide class of
cellular dynamics in chemical, biological, and engineering systems. We confirm
our results by direct numerical simulations.Comment: 4 pages, 3 figures, RevTe
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