746 research outputs found
Coupling constants and transition potentials for hadronic decay modes of a meson
Within the independent-harmonic-oscillator model for quarks inside a hadron,
a rigorous method is presented for the calculation of coupling constants and
transition potentials for hadronic decay, as needed in a multi-channel
description of mesons.Comment: 19 pages, 4 figure
Continuum bound states K-long, D_{1}(2420), D_{s1}(2536) and their partners K-short, D_{1}(2400), D*_{sJ}(2463)
The very recently observed meson is described as a
bound state in a unitarised meson model, owing its
existence to the strong OZI-allowed coupling to the nearby -wave
threshold. By the same non-perturbative mechanism, the narrow
axial-vector resonance shows up as a quasi-bound-state partner
embedded in the continuum. With the same model and parameters, it
is also shown that the preliminary broad resonance and
the established narrow may be similar
partners, as a result of the strong OZI-allowed coupling to the
nearby -wave threshold. The continuum bound states
(2420) and are found to be mixtures of 33%
and 67% , whereas their partners and
have more or less the opposite -state
content, but additionally with some or admixture,
respectively.
The employed mechanism also reproduces the ratio of the - mass
difference and the width, by describing as a bound state
embedded in the continuum. The model's results for
states containing one quark are also discussed.Comment: 11 pages, plain LaTeX, v2:relation to work of Kokoski and Godfrey in
conclusions and more references v3:B-states included. More reference
Recoupling matrix elements and decay
Recoupling matrix elements are evaluated, in the harmonic oscillator
approximation, for all possible angular and radial excitations in processes
where quarks recombine. A diagrammatic representation is given. Their use is
demonstrated in calculating the transition potential for rho to two pions in a
pair creation model.Comment: 15 pages, 10 figure
Deep level transient spectroscopy study for the development of ion-implanted silicon field-effect transistors for spin-dependent transport
A deep level transient spectroscopy (DLTS) study of defects created by
low-fluence, low-energy ion implantation for development of ion-implanted
silicon field-effect transistors for spin-dependent transport experiments is
presented. Standard annealing strategies are considered to activate the
implanted dopants and repair the implantation damage in test
metal-oxide-semiconductor (MOS) capacitors. Fixed oxide charge, interface
trapped charge and the role of minority carriers in DLTS are investigated. A
furnace anneal at 950 C was found to activate the dopants but did not
repair the implantation damage as efficiently as a 1000 C rapid
thermal anneal. No evidence of bulk traps was observed after either of these
anneals. The ion- implanted spin-dependent transport device is shown to have
expected characteristics using the processing strategy determined in this
study.Comment: 4 pages, 6 figure
Optical and electronic properties of sub-surface conducting layers in diamond created by MeV B-implantation at elevated temperatures
Boron implantation with in-situ dynamic annealing is used to produce highly
conductive sub-surface layers in type IIa (100) diamond plates for the search
of a superconducting phase transition. Here we demonstrate that high-fluence
MeV ion-implantation, at elevated temperatures avoids graphitization and can be
used to achieve doping densities of 6 at.%. In order to quantify the diamond
crystal damage associated with implantation Raman spectroscopy was performed,
demonstrating high temperature annealing recovers the lattice. Additionally,
low-temperature electronic transport measurements show evidence of charge
carrier densities close to the metal-insulator-transition. After electronic
characterization, secondary ion mass spectrometry was performed to map out the
ion profile of the implanted plates. The analysis shows close agreement with
the simulated ion-profile assuming scaling factors that take into account an
average change in diamond density due to device fabrication. Finally, the data
show that boron diffusion is negligible during the high temperature annealing
process.Comment: 22 pages, 6 figures, submitted to JA
A low-lying scalar meson nonet in a unitarized meson model
A unitarized nonrelativistic meson model which is successful for the
description of the heavy and light vector and pseudoscalar mesons yields, in
its extension to the scalar mesons but for the same model parameters, a
complete nonet below 1 GeV. In the unitarization scheme, real and virtual
meson-meson decay channels are coupled to the quark-antiquark confinement
channels. The flavor-dependent harmonic-oscillator confining potential itself
has bound states epsilon(1.3 GeV), S(1.5 GeV), delta(1.3 GeV), kappa(1.4 GeV),
similar to the results of other bound-state qqbar models. However, the full
coupled-channel equations show poles at epsilon(0.5 GeV), S(0.99 GeV),
delta(0.97 GeV), kappa(0.73 GeV). Not only can these pole positions be
calculated in our model, but also cross sections and phase shifts in the
meson-scattering channels, which are in reasonable agreement with the available
data for pion-pion, eta-pion and Kaon-pion in S-wave scattering.Comment: A slightly revised version of Zeitschrift fuer Physik C30, 615 (1986
Effective restoration of the U_A(1) symmetry with temperature and density
We investigate the full U(3)U(3) chiral symmetry restoration, at
finite temperature and density, on the basis of a quark model which
incorporates the most relevant properties of QCD in this context: explicit and
spontaneous breaking of chiral symmetry and axial U(1) symmetry breaking. A
specific lattice-inspired behavior of the topological susceptibility, combined
with the convergence of chiral partners, signals the onset of an effective
chiral symmetry restoration. The results suggest that the axial part of the
symmetry is restored before the possible restoration of the full
U(3)U(3) chiral symmetry can occur. This conclusion is valid in the
context of both finite temperature and density.Comment: 5 pages, 2 figures; PRD versio
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