35,425 research outputs found
Determination of and Extraction of from Semileptonic Decays
By globally analyzing all existing measured branching fractions and partial
rates in different four momentum transfer-squared bins of decays, we obtain the product of the form factor and magnitude of
CKM matrix element to be . With this
product, we determine the semileptonic form factor
in conjunction with the value of
determined from the SM global fit. Alternately, with the product together with
the input of the form factor calculated in lattice QCD recently, we
extract , where the error is
still dominated by the uncertainty of the form factor calculated in lattice
QCD. Combining the
extracted from all existing measurements of decays and
together, we find the most
precisely determined to be , which improves
the accuracy of the PDG'2014 value by
A new effective interaction for the trapped Fermi gas
We apply the configuration-interaction method to calculate the spectra of
two-component Fermi systems in a harmonic trap, studying the convergence of the
method at the unitary interaction limit. We find that for a fixed
regularization of the two-body interaction the convergence is exponential or
better in the truncation parameter of the many-body space. However, the
conventional regularization is found to have poor convergence in the
regularization parameter, with an error that scales as a low negative power of
this parameter. We propose a new regularization of the two-body interaction
that produces exponential convergence for systems of three and four particles.
From the systematics, we estimate the ground-state energy of the
four-particle system to be (5.05 +- 0.024)hbar omega.Comment: 4 pages, 3 figure
The Integrative Model of International Innovation Network and Performance
Research in social network has demonstrated that firms in changing environment will benefit from innovation network. However, the lack of consensus on what factors and how these factors impact the performance impedes the further research in this area. In this paper, the concept of international innovation network and its performance are clarified. Then, based on reviews of the social network and knowledge management literature, especially along with the results of previous empirical studies, we propose an integrative model in which the performance of focal firm within international innovation network is impacted by network structure (network range and density), network relationship (tie strength, duration, and norm distance), and network position (centrality). We also come up with some efforts that the firm can make in order to improve its performance. In the end, the future research following this study is discussed
Nuclear modification factor in intermediate-energy heavy-ion collisions
The transverse momentum dependent nuclear modification factors (NMF), namely
, is investigated for protons produced in Au + Au at 1 GeV within
the framework of the isospin-dependent quantum molecular dynamics (IQMD) model.
It is found that the radial collective motion during the expansion stage
affects the NMF at low transverse momentum a lot. By fitting the transverse
mass spectra of protons with the distribution function from the Blast-Wave
model, the magnitude of radial flow can be extracted. After removing the
contribution from radial flow, the can be regarded as a thermal one
and is found to keep unitary at transverse momentum lower than 0.6 GeV/c and
enhance at higher transverse momentum, which can be attributed to Cronin
effect.Comment: 8 pages, 5 figures; aceepted by Physics Letters
Physical mechanism of superluminal traversal time: interference between multiple finite wave packets
The mechanism of superluminal traversal time through a potential well or
potential barrier is investigated from the viewpoint of interference between
multiple finite wave packets, due to the multiple reflections inside the well
or barrier. In the case of potential-well traveling that is classically
allowed, each of the successively transmitted constituents is delayed by a
subluminal time. When the thickness of the well is much smaller in comparision
with a characteristic length of the incident wave packet, the reshaped wave
packet in transmission maintains the profile of the incident wave packet. In
the case of potential-barrier tunneling that is classically forbidden, though
each of the successively transmitted constituents is delayed by a time that is
independent of the barrier thickness, the interference between multiple
transmitted constituents explains the barrier-thickness dependence of the
traversal time for thin barriers and its barrier-thickness independence for
thick barriers. This manifests the nature of Hartman effect.Comment: 9 pages, 3 figures, Some comments and suggestions are appreciate
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