1,913 research outputs found
A method for getting a finite in the IR region from an all-order beta function
The analytical method of QCD running coupling constant is extended to a model
with an all-order beta function which is inspired by the famous
Novikov-Shifman-Vai\-n\-s\-htein-Zakharov beta function of N=1 supersymmetric
gau\-g\-e theories. In the approach presented here, the running coupling is
determined by a transcendental equation with non-elementary integral of the
running scale . In our approach , which reads 0.30642,
does not rely on any dimensional parameters. This is in accordance with results
in the literature on the analytical method of QCD running coupling constant.
The new "analytically im\-p\-roved" running coupling constant is also
compatible with the property of asymptotic freedom.Comment: 5 pages, 3 figure
Background field method in the large expansion of scalar QED
Using the background field method, we, in the large approximation,
calculate the beta function of scalar quantum electrodynamics at the first
nontrivial order in by two different ways. In the first way, we get the
result by summing all the graphs contributing directly. In the second way, we
begin with the Borel transform of the related two point Green's function. The
main results are that the beta function is fully determined by a simple
function and can be expressed as an analytic expression with a finite radius of
convergence, and the scheme-dependent renormalized Borel transform of the two
point Green's function suffers from renormalons.Comment: 13 pages, 4 figures, 1 table, to appear in the European Physical
Journal
Proposal of Direct Search for Strongly Bound States of ppbar, npbar Systems with High Intensity and Collective pbar beam
In this letter, we discuss the possibility to look for the direct evidence of
the existence of the ppbar and npbar bound states. Measurement of the single
\gamma ray from the ppbar and npbar systems at rest can directly confirm
whether the X(1860) and X(1835) are the resonances which are strongly coupled
to ppbar. In addition to the neutral candidate, a charged resonance is
also proposed to be searched for in npbar channel. We find that the data from
the Crystal Barrel experiment at LEAR/CERN can be used to confirm the X(1835)
observed by BES Collaboration. The possibility of measuring the
spectrum below 100 MeV at the new experiment with cold high intensity \pbar
beam at GSI is discussed. These new techniques can be used to probe the
structure of the X(1860) and X(1835) in the future.Comment: Accepted by Mod. Phys. Lett.
An Analytical Solution in Detuned Two Level Systems
Finding the evolution of two level Hamiltonian is of great importance in
quantum computation and quantum precision manipulation due to the requirement
of quantum experiment control. However, the Schr\"odinger equation of an
arbitrary time-dependent two level Hamiltonian is hardly solvable due to its
non-commutativity Hamiltonian in different times. In this article, we expand
and demonstrate an exact solution of Schr\"odinger equation respect to general
two level systems with a few limitations. This analytical solution has lots of
manipulative parameters and a few boundary restrictions, which could drive many
applications. Furthermore, we show the adaptive capacity of our scheme, which
demonstrated the widely use of our scheme, and make it suitable for most of
experiment Hamiltonian directly
Optimized Design on the Width and Spacing of the Cross Passageway in Tunnels
AbstractCross passageways have been commonly applied in the evacuation system of tunnels, and the width and spacing of the cross passageways decide the evacuation capacity of the tunnel. In design, increasing the width of the cross passageways and reducing their spacing can improve the evacuation ability of tunnels. However, it will certainly increase the cost of the project. Under the precondition of meeting evacuation requirements, an optimization model was established in this article, which aimed at reducing the cost of the project. Finally, discussions on the application of this optimization model were carried on, and this method may provide reference for designing cross passageways
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