870 research outputs found
Multichannel calculation for Ds* vector states and the Ds(2632) resonance
We study bound states below threshold and resonances above threshold in the
D0-K+ and Ds-eta systems, using a many-coupled-channel model for non-exotic
meson-meson scattering applied to states with the quantum numbers of c-sbar
quark-antiquark vector mesons. We fit the ground state at 2.112 GeV, whence the
lowest resonances in D0-K+ come out at 2.61, 2.72, 3.03, and 3.08 GeV. The
resonance at 2.61 GeV acquires a width of about 8 MeV, while its partial P-wave
cross section is up to six times larger in Ds-eta than in D0-K+, provided a
mechanism accounting for Okubo-Zweig-Iizuka--forbidden decays is included. The
latter finding is in agreement with the observations of the SELEX collaboration
with respect to the recently reported DsJ(2632) resonance. Therefore, we
conclude that the DsJ(2632) is most probably the first recurrence excitation of
the Ds*(2112) meson.Comment: 11 pages, 6 figures; v2: Significant improvements for threshold
behavior, and for the hadronic widths by including additional two-meson
channels. Misprints in formulas correcte
A very broad X(4260) and the resonance parameters of the 3D vector charmonium state
We argue that the X(4260) enhancement contains a wealth of information on
vector c-cbar spectroscopy. We discuss the shape of the X(4260) observed in the
OZI-forbidden process "electron-positron into J/psi and a pair of charged
pions", in particular at and near vector charmonium resonances as well as
open-charm threshold enhancements. The resulting very broad X(4260) structure
does not seem to classify itself as a vector charmonium resonance, but its
detailed shape allows to identify new vector c-cbar states. Here, we estimate
the resonance parameters of the psi(3D) state.Comment: 4 pages, 5 figures; version 2: 2 figures replace
The complex relation between production and scattering amplitudes
The unitarity relation, Im(A)=T* A, is derived for a three-body production
amplitude, A, that consists of a complex linear combination of elements of the
two-body scattering amplitude, T. We conclude that the unitarity relation does
not impose a realness condition on the coefficients in the expansion of, A, in
terms of, T.Comment: 4 pages plain LaTe
Multichannel calculation of excited vector resonances and the
A multichannel calculation of excited states is
carried out within a generalization of the Resonance-Spectrum Expansion, which
may shed light on the classification of the resonance, discovered
by BABAR and originally denoted X(2175). In this framework, a complete spectrum
of bare states is coupled to those OZI-allowed decay channels that
should be most relevant for the considered energy range. The included - and
-wave two-meson channels comprise the lowest pseudoscalar, vector, scalar,
and axial-vector mesons, while in the sector both the and
states are coupled. The only two free parameters are tuned so as to
reproduce mass and width of the , but come out reasonably close to
previously used values. Among the model's -matrix poles, there are good
candidates for observed resonances, as well other ones that should exist
according to the quark model. Besides the expected resonances as unitarized
confinement states, a dynamical resonance pole is found at MeV.
The huge width makes its interpretation as the somewhat dubious,
but further improvements of the model may change this conclusion.Comment: 6 pages, 5 figures, RevTex4; v2: very recent experimental result,
some extra discussion, and 2 references added; v3: 3 new figures, 2 new
equations, and some rephrasing; version accepted for publication in Phys.
Rev.
Carry-Along Trade.
New empirical and theoretical work has highlighted the importance of multi-product fi…rms in international trade flows. We examine multi-product exporters in the small open economy of Belgium. Linking production and export data at the fi…rm-product level, we discover new and, heretofore, unknown facts about multi-product manufacturing exporters. The large majority of Belgian manufacturing …firms export products that they do not produce. More than three quarters of the exported products and more than one quarter of export value from Belgian manufacturers are in goods that are not produced by the …rm, so-called Carry-Along Trade (CAT). CAT exports are concentrated in the largest and most productive …rms and CAT exports respond di¤erently to variation in …rm productivity and size than do exports of goods that the …rm produces.
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
Organic Compounds and Genotoxicity in Drinking Water
Until recently only lipophilic compounds were analysed in any research on the occurrence of mutanogenic and carcinogenic compounds in water. They were isolated using XAD-resins. They contain approximately half of the total organic material present in water. A clear mutanogenic effect was demonstrated for these compounds using Amestest. The hydrophilic fraction of the organic material was difficult to investigate because of problems with isolation and analysis caused by its high solubility. The high solubility means in practice that the hydrophilic compounds are mobile in conventional treatment systems and in soil and can easily penetrate into drinking water. A method was developed to isolate hydrophilic compounds using a combination of ion exchange and a clean-up with a XAD-resin. The isolated compounds were examined with the Amestest for the presence of mutanogenic compounds. For some tested water types a mutanogenic effect was found in the lipophilic material. Due to oxidation with ozone, mutanogenic compounds can be formed from (non-mutanogenic) industrial pollutions. No mutanogenic activity was found in the hydrophilic organic material of all examined water types, even after ozone oxidation or chlorination. It was hypothesized that hydrophilic compounds can not reach the DNA of the cell, thus they do not play any (geno) toxicological role
Comment on Intrinsic and dynamically generated scalar meson states
The scalar-meson assignments of Shakin and Wang in a generalized
Nambu--Jona-Lasinio model are contradicted by recent experimental information.
Also the strict distinction made by these authors between ``intrinsic'' and
``dynamically generated'' states is contested, as well as a number of other
statements.Comment: 7 pages, (v2 cosmetics, v3 corrections in one reference), to be
published in Phys.Rev.
Electrically detected magnetic resonance using radio-frequency reflectometry
The authors demonstrate readout of electrically detected magnetic resonance
at radio frequencies by means of an LCR tank circuit. Applied to a silicon
field-effect transistor at milli-kelvin temperatures, this method shows a
25-fold increased signal-to-noise ratio of the conduction band electron spin
resonance and a higher operational bandwidth of > 300 kHz compared to the kHz
bandwidth of conventional readout techniques. This increase in temporal
resolution provides a method for future direct observations of spin dynamics in
the electrical device characteristics.Comment: 9 pages, 3 figure
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
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