5,359 research outputs found
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.
Factorization and Unitarity in Superstring Theory
The overall coefficient of the two-loop 4-particle amplitude in superstring
theory is determined by making use of the factorization and unitarity. To
accomplish this we computed in detail all the relevant tree and one-loop
amplitudes involved and determined their overall coefficients in a consistent
way.Comment: LaTex file, 19 pages, 4 figures; v2, minor corrections and figures
corrected; v3, minor corrections with the English, to be published in JHE
Radiative decays of the strange-bottom mesons
In this article, we assume that the strange-bottom mesons are the
conventional mesons, and calculate the electromagnetic coupling
constants , , and using the light-cone QCD sum rules. Then
we study the radiative decays , ,
and , and observe that the
widths are rather narrow. We can search for the strange-bottom
mesons in the invariant and mass distributions in the
strong decays or in the invariant and mass
distributions in the radiative decays.Comment: 16 pages, 4 figures, revised versio
Effects of relative orientation of the molecules on electron transport in molecular devices
Effects of relative orientation of the molecules on electron transport in
molecular devices are studied by non-equilibrium Green's function method based
on density functional theory. In particular, two molecular devices, with the
planer Au and Ag clusters sandwiched between the Al(100) electrodes
are studied. In each device, two typical configurations with the clusters
parallel and vertical to the electrodes are considered. It is found that the
relative orientation affects the transport properties of these two devices
completely differently. In the Al(100)-Au-Al(100) device, the conductance
and the current of the parallel configuration are much larger than those in the
vertical configuration, while in the Al(100)-Ag-Al(100) device, an
opposite conclusion is obtained
Factorization of the Two Loop Four-Particle Amplitude in Superstring Theory Revisited
We study in detail the factorization of the newly obtained two-loop
four-particle amplitude in superstring theory. In particular some missing
factors from the scalar correlators are obtained correctly, in comparing with a
previous study of the factorization in two-loop superstring theory. Some
details for the calculation of the factorization of the kinematic factor are
also presented.Comment: 11 pages, 1 figure; v2, minor corrections and references update
Evolving small-world networks with geographical attachment preference
We introduce a minimal extended evolving model for small-world networks which
is controlled by a parameter. In this model the network growth is determined by
the attachment of new nodes to already existing nodes that are geographically
close. We analyze several topological properties for our model both
analytically and by numerical simulations. The resulting network shows some
important characteristics of real-life networks such as the small-world effect
and a high clustering.Comment: 11 pages, 4 figure
Determination of virtual water content of rice and spatial characteristics analysis in China
China is a water-stressed country, and agriculture consumes the bulk of its
water resources. Assessing the virtual water content (VWC) of crops is one
important way to develop efficient water management measures to alleviate
water resource conflicts among different sectors. In this research, the VWC
of rice, a major crop in China, is taken as the research object. China
covers a vast land area, and the VWC of rice varies widely between different
regions. The VWC of rice in China is assessed and the spatial
characteristics are also analysed. The total VWC is the total volume
of freshwater both consumed and affected by pollution during the crop
production process, including both direct and indirect water use. Prior
calculation frameworks of the VWC of crops did not contain all of the
virtual water content of crops. In addition to the calculation of green,
blue and grey water – the direct water in VWC – the indirect water use of
rice was also calculated, using an input–output model. The percentages of
direct green, blue, grey and indirect water in the total VWC of rice in
China were found to be 43.8, 28.2, 27.6, and 0.4%. The total VWC of rice
generally showed a roughly three-tiered distribution, and decreased from
southeast to northwest. The higher values of direct green water usage were
mainly concentrated in Southeast and Southwest China, while the values
were relatively low in Northwest China and Inner Mongolia. The higher direct
blue water values were mainly concentrated in the eastern and southern
coastal regions and Northwest China, and low values were mainly concentrated
in Southwest China. Grey water values were relatively high in Shanxi and
Guangxi provinces and low in Northeast and Northwest China. The regions with
high values for indirect water were randomly distributed but the regions
with low values were mainly concentrated in Northwest and Southwest China.
For the regions with relatively high total VWC the high values of blue water
made the largest contribution, although for the country as a whole the
direct green water is the most important contributor
Testing CPT Invariance in B^0_d-\bar{B}^0_d and B^0_s-\bar{B}^0_s Oscillations
Recent CDF and D0 measurements of B^0_s-\bar{B}^0_s mixing make it possible
to search for CP violation and test CPT symmetry in a variety of B_s decays.
Considering both coherent B^0_d\bar{B}^0_d decays at the \Upsilon (4S)
resonance and coherent B^0_s\bar{B}^0_s decays at the \Upsilon (5S) resonance,
we formulate their time-dependent and time-integrated rates by postulating
small CPT violation in B^0_d-\bar{B}^0_d and B^0_s-\bar{B}^0_s oscillations. We
show that the opposite-sign dilepton events from either C-odd or C-even
B^0_q\bar{B}^0_q states (for q = d or s) can be used to determine or constrain
the CPT-violating parameter at a super-B factory. The possibility of
distinguishing between the effect of CPT violation and that of \Delta B =
-\Delta Q transitions is also discussed.Comment: LaTex 12 pages. A minor change. Accepted for publication in Phys.
Rev.
Transitions To the Long-Resident State in coupled chaotic oscillators
The behaviors of coupled chaotic oscillators before complete synchronization
were investigated. We report three phenomena: (1) The emergence of long-time
residence of trajectories besides one of the saddle foci; (2) The tendency that
orbits of the two oscillators get close becomes faster with increasing the
coupling strength; (3) The diffusion of two oscillator's phase difference is
first enhanced and then suppressed. There are exact correspondences among these
phenomena. The mechanism of these correspondences is explored. These phenomena
uncover the route to synchronization of coupled chaotic oscillators.Comment: 3 pages, 5 figure
More Straightforward Extraction of the Fundamental Lepton Mixing Parameters from Long-Baseline Neutrino Oscillations
We point out the simple reversibility between the fundamental neutrino mixing
parameters in vacuum and their effective counterparts in matter. The former can
therefore be expressed in terms of the latter, allowing more straightforward
extraction of the genuine lepton mixing quantities from a variety of
long-baseline neutrino oscillation experiments. In addition to the
parametrization-independent results, we present the formulas based on the
standard parametrization of the lepton flavor mixing matrix and give a typical
numerical illustration.Comment: RevTex 10 pages. Minor changes. Phys. Rev. D in printin
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