1,301 research outputs found
Deeply Virtual Pseudoscalar Meson Production with CLAS
Deeply virtual meson scattering cross sections and asymmetries for the pi^0
and eta exclusive electroproduction in a very wide kinematic range of Q^2, t
and x_B have been measured with CLAS (JLab). Initial analysis is already
showing remarkable results. These data will help us to better understand the
transition from soft to hard mechanisms.Comment: Prepared for XII Workshop on High Energy Spin Physics DSPIN-07,
Dubna, September 3-7, 200
Connection between the elastic GEp/GMp and P to Delta form factors
It is suggested that the falloff in Qsq of the P to Delta magnetic form
factor GM* is related to the recently observed falloff of the elastic electric
form factor GEp/GMp. Calculation is carried out in the framework of a GPD
mechanism
Cosmological Perturbations of Quantum-Mechanical Origin and Anisotropy of the Microwave Background
Cosmological perturbations generated quantum-mechanically (as a particular
case, during inflation) possess statistical properties of squeezed quantum
states. The power spectra of the perturbations are modulated and the angular
distribution of the produced temperature fluctuations of the CMBR is quite
specific. An exact formula is derived for the angular correlation function of
the temperature fluctuations caused by squeezed gravitational waves. The
predicted angular pattern can, in principle, be revealed by the COBE-type
observations.Comment: 9 pages, WUGRAV-92-17 Accepted for Publication in Phys. Rev. Letters
(1993
Scaling and Duality in Semi-exclusive Processes
We discuss extending scaling and duality studies to semi-exclusive processes.
We show that semi-exclusive hard pion photoproduction should exhibit scaling
behavior in kinematic regions where the photon and pion both interact directly
with the same quark. We show that such kinematic regions exist. We also show
that the constancy with changing momentum transfer of the resonance
peak/scaling curve ratio, familiar for many resonances in deep inelastic
scattering, is also expected in the semi-exclusive case.Comment: 8 pages, 4 figures, submitted to Phys.Rev.
Roper excitation in reactions
We calculate differential cross sections and the spin transfer coefficient
in the reaction for proton
bombarding energies from 1 to 10 GeV and invariant masses spanning
the region of the N(1440) Roper resonance. Two processes --
excitation in the -particle and Roper excitation in the proton -- are
included in an effective reaction model which was shown previously to reproduce
existing inclusive spectra. The present calculations demonstrate that these two
contributions can be clearly distinguished via , even under kinematic
conditions where cross sections alone exhibit no clear peak structure due to
the excitation of the Roper.Comment: 12 pages, 11 ps figures, Late
Generating and Revealing a Quantum Superposition of Electromagnetic Field Binomial States in a Cavity
We introduce the -photon quantum superposition of two orthogonal
generalized binomial states of electromagnetic field. We then propose, using
resonant atom-cavity interactions, non-conditional schemes to generate and
reveal such a quantum superposition for the two-photon case in a single-mode
high- cavity. We finally discuss the implementation of the proposed schemes.Comment: 4 pages, 3 figures. Title changed (published version
Linear amplification and quantum cloning for non-Gaussian continuous variables
We investigate phase-insensitive linear amplification at the quantum limit
for single- and two-mode states and show that there exists a broad class of
non-Gaussian states whose nonclassicality survives even at an arbitrarily large
gain. We identify the corresponding observable nonclassical effects and find
that they include, remarkably, two-mode entanglement. The implications of our
results for quantum cloning outside the Gaussian regime are also addressed.Comment: published version with reference updat
Comparison of Efficacy and Safety of Transcatheter Aortic Valve Implantation in Patients With Bicuspid Versus Tricuspid Aortic Valves
Bicuspid aortic valve (BAV) stenosis has been considered a contraindication to transcatheter aortic valve implantation (TAVI). The aim of this study is to compare the efficacy and safety of TAVI in patients with BAV with those with tricuspid aortic valve (TAV) using balloon-expandable and self-expanding transcatheter heart valves. This retrospective study included 823 consecutive patients with severe, symptomatic aortic valve stenosis undergoing TAVI in 2 institutions, Baylor Heart and Vascular Hospital (Dallas, TX) and The Heart Hospital Baylor Plano (Plano, TX), from January 2012 to February 2016. Efficacy was evaluated by postprocedural valve function as mean gradient, peak velocity, effective orifice area, and ≥moderate paravalvular leak. Safety end points included all-cause 30-day and 1-year mortality, immediate postprocedural mortality and 30-day cardiovascular mortality, procedural success, pacemaker implantation, and procedural complications. Of the 823 included patients, 735 had TAV and 77 had BAV. Baseline characteristics were similar between the 2 groups. Procedural success was high in both BAV and TAV (98.7% vs 99.1%, p = ns). There were no significant differences between groups in valve hemodynamics after TAVI, pacemaker implantation rate, or procedural complications. There were no differences regarding immediate postprocedural mortality (BAV vs TAV, 1.1% vs 0.8%, p = ns), nor 30-day cardiovascular mortality (3.4% vs 2.3%, p = ns). All-cause mortality at 30 days (3.4% vs 3.1%, p = ns) and 1-year (8.5% vs 10.5%) were similar. Patients with BAV showed similar procedural and clinical outcomes to patients with TAV. Therefore, TAVI appears to be a safe and effective procedure for patients with BAVs as well as those with TAVs
Coherent and squeezed states of quantum Heisenberg algebras
Starting from deformed quantum Heisenberg Lie algebras some realizations are
given in terms of the usual creation and annihilation operators of the standard
harmonic oscillator. Then the associated algebra eigenstates are computed and
give rise to new classes of deformed coherent and squeezed states. They are
parametrized by deformed algebra parameters and suitable redefinitions of them
as paragrassmann numbers. Some properties of these deformed states also are
analyzed.Comment: 32 pages, 3 figure
Sum Rule Description of Color Transparency
The assumption that a small point-like configuration does not interact with
nucleons leads to a new set of sum rules that are interpreted as models of the
baryon-nucleon interaction. These models are rendered semi-realistic by
requiring consistency with data for cross section fluctuations in proton-proton
diffractive collisions.Comment: 22 pages + 3 postscript figures attache
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