2,317 research outputs found
, and molecules
We investigate theoretically baryon systems made of three hadrons which
contain one nucleon and one D meson, and in addition another meson, or . The systems are studied using the Fixed Center Approximation
to the Faddeev equations. The study is made assuming scattering of a or a
on a cluster, which is known to generate the ,
or the scattering of a nucleon on the cluster, which has been shown
to generate a hidden charm resonance named X(3700). We also investigate the
configuration of scattering of on the cluster, which is known to
generate the . In all cases we find bound states, with the
system, of exotic nature, more bound than the .Comment: 9 figure
One-Nucleon Effective Generators of the Poincare Group derived from a Field Theory: Mass Renormalization
We start from a Lagrangian describing scalar "nucleons" and mesons which
interact through a simple vertex. Okubo's method of unitary transformation is
used to describe a single nucleon dressed by its meson cloud. We find an
expression for the physical mass of the nucleon being correct up to second
order in the coupling constant. It is then verified that this result is the
same as the corresponding expression found by Feynman techniques. Finally we
also express the three boost operators in terms of the physical nucleon mass.
Doing so we find expressions for all the ten generators of Poincar\'e
transformations for the system of one single dressed nucleon.Comment: 19 pages, no figure
Scattering of neutrinos on a polarized electron target as a test for new physics beyond the Standard Model
In this paper, we analyze the scattering of the neutrino beam on the
polarized electron target, and predict the effects of two theoretically
possible scenarios beyond the Standard Model. In both scenarios, Dirac
neutrinos are assumed to be massive.
First, we consider how the existence of CP violation phase between the
complex vector V and axial A couplings of the Left-handed neutrinos affects the
azimuthal dependence of the differential cross section. The future superbeam
and neutrino factory experiments will provide the unique opportunity for the
leptonic CP violation studies, if the large magnetized sampling calorimeters
with good event reconstruction capabilities are build.
Next, we take into account a scenario with the participation of the exotic
scalar S coupling of the Right-handed neutrinos in addition to the standard
vector V and axial A couplings of the Left-handed neutrinos. The main goal is
to show how the presence of the R-handed neutrinos, in the above process
changes the spectrum of recoil electrons in relation to the expected Standard
Model prediction, using the current limits on the non-standard couplings. The
interference terms between the standard and exotic couplings in the
differential cross section depend on the angle between the transverse
incoming neutrino polarization and the transverse electron polarization of the
target, and do not vanish in the limit of massless neutrino. The detection of
the dependence on this angle in the energy spectrum of recoil electrons would
be a signature of the presence of the R-handed neutrinos in the
neutrino-electron scattering. To make this test feasible, the polarized
artificial neutrino source needs to be identified.Comment: 11 pages, 3 eps figures, revtex, submitted to publicatio
Langevin Trajectories between Fixed Concentrations
We consider the trajectories of particles diffusing between two infinite
baths of fixed concentrations connected by a channel, e.g. a protein channel of
a biological membrane. The steady state influx and efflux of Langevin
trajectories at the boundaries of a finite volume containing the channel and
parts of the two baths is replicated by termination of outgoing trajectories
and injection according to a residual phase space density. We present a
simulation scheme that maintains averaged fixed concentrations without creating
spurious boundary layers, consistent with the assumed physics
Genetic variability and incidence of systemic diseases in wild vines (Vitis vinifera ssp. silvestris) along the Danube
In the riparian woods of Danube and March east of Vienna 87 wild specimens of Vitis vinifera ssp. silvestris were genetically analysed and compared. The silvestris population can be split into 6 distinct groups, but this clustering cannot be explained solely by the geographical distance. The unique genetic variability observed represents a strong case for preservation of wild grapevines.The incidence of bacterioses, viroses and nematodes transmitting nepoviruses to these vines were registered. None of the analysed specimens suffered from Agrobacterium vitis-induced crown gall. Only some vines were infected by viral pathogens such as GLRaV I and SLRV. Thus the wild vines do not constitute a risk for the surrounding commercial vineyards. On the other hand, diseases spread from cultivated grapevines may seriously harm the wild vine population. Four species of nematodes transmitting nepoviruses were registered. Samples of Xiphinema vuittenezi and Longidorus attenuatus from the Lobau (natural forests, north of the Danube in the area of Vienna) differ morphometrically from others found on arable soils or isolated from the research area.
On the zig-zag pilot-wave approach for fermions
We consider a pilot-wave approach for the Dirac theory that was recently
proposed by Colin and Wiseman. In this approach, the particles perform a
zig-zag motion, due to stochastic jumps of their velocity. We respectively
discuss the one-particle theory, the many-particle theory and possible
extensions to quantum field theory. We also discuss the non-relativistic limit
of the one-particle theory. For a single particle, the motion is always
luminal, a feature that persists in the non-relativistic limit. For more than
one particle the motion is in general subluminal.Comment: 23 pages, no figures, LaTe
Entanglement of Dirac fields in non-inertial frames
We analyze the entanglement between two modes of a free Dirac field as seen
by two relatively accelerated parties. The entanglement is degraded by the
Unruh effect and asymptotically reaches a non-vanishing minimum value in the
infinite acceleration limit. This means that the state always remains entangled
to a degree and can be used in quantum information tasks, such as
teleportation, between parties in relative uniform acceleration. We analyze our
results from the point of view afforded by the phenomenon of entanglement
sharing and in terms of recent results in the area of multi-qubit
complementarity.Comment: 15 pages, with 8 figures (Mar 2006); accepted to Physical Review A,
July 2006 - slightly revise
Predictors and outcomes of crossover to surgery from physical therapy for meniscal tear and osteoarthritis a randomized trial comparing physical therapy and surgery
BACKGROUND: Arthroscopic partial meniscectomy (APM) combined with physical therapy (PT) have yielded pain relief similar to that provided by PT alone in randomized trials of subjects with a degenerative meniscal tear. However, many patients randomized to PT received APM before assessment of the primary outcome. We sought to identify factors associated with crossing over to APM and to compare pain relief between patients who had crossed over to APM and those who had been randomized to APM. METHODS: We used data from the MeTeOR (Meniscal Tear in Osteoarthritis Research) Trial of APM with PT versus PT alone in subjects ≥45 years old who had mild-to-moderate osteoarthritis and a degenerative meniscal tear. We assessed independent predictors of crossover to APM among those randomized to PT. We also compared pain relief at 6 months among those randomized to PT who crossed over to APM, those who did not cross over, and those originally randomized to APM. RESULTS: One hundred and sixty-four subjects were randomized to and received APM and 177 were randomized to PT, of whom 48 (27%) crossed over to receive APM in the first 140 days after randomization. In multivariate analyses, factors associated with a higher likelihood of crossing over to APM among those who had originally been randomized to PT included a baseline Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) Pain Score of ≥40 (risk ratio [RR] = 1.99; 95% confidence interval [CI] = 1.00, 3.93) and symptom duration of <1 year (RR = 1.74; 95% CI = 0.98, 3.08). Eighty-one percent of subjects who crossed over to APM and 82% of those randomized to APM had an improvement of ≥10 points in their pain score at 6 months, as did 73% of those who were randomized to and received only PT. CONCLUSIONS: Subjects who crossed over to APM had presented with a shorter symptom duration and greater baseline pain than those who did not cross over from PT. Subjects who crossed over had rates of surgical success similar to those of the patients who had been randomized to surgery. Our findings also suggest that an initial course of rigorous PT prior to APM may not compromise surgical outcome. LEVEL OF EVIDENCE: Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence
Laser photon merging in proton-laser collisions
The quantum electrodynamical vacuum polarization effects arising in the
collision of a high-energy proton beam and a strong, linearly polarized laser
field are investigated. The probability that laser photons merge into one
photon by interacting with the proton`s electromagnetic field is calculated
taking into account the laser field exactly. Asymptotics of the probability are
then derived according to different experimental setups suitable for detecting
perturbative and nonperturbative vacuum polarization effects. The
experimentally most feasible setup involves the use of a strong optical laser
field. It is shown that in this case measurements of the polarization of the
outgoing photon and and of its angular distribution provide promising tools to
detect these effects for the first time.Comment: 38 pages, 9 figure
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