17,988 research outputs found
Coupled Breathing Oscillations of Two-Component Fermion Condensates in Deformed Traps
We investigate collective excitations coupled with monopole and quadrupole
oscillations in two-component fermion condensates in deformed traps. The
frequencies of monopole and dipole modes are calculated using Thomas-Fermi
theory and the scaling approximation. When the trap is largely deformed, these
collective motions are decoupled to the transverse and longitudinal breathing
oscillation modes. As the trap approaches becoming spherical, however, they are
coupled and show complicated behaviors.Comment: 18 pages and 8 figure
Convergence of the Gaussian Expansion Method in Dimensionally Reduced Yang-Mills Integrals
We advocate a method to improve systematically the self-consistent harmonic
approximation (or the Gaussian approximation), which has been employed
extensively in condensed matter physics and statistical mechanics. We
demonstrate the {\em convergence} of the method in a model obtained from
dimensional reduction of SU() Yang-Mills theory in dimensions. Explicit
calculations have been carried out up to the 7th order in the large-N limit,
and we do observe a clear convergence to Monte Carlo results. For the convergence is already achieved at the 3rd order, which suggests that
the method is particularly useful for studying the IIB matrix model, a
conjectured nonperturbative definition of type IIB superstring theory.Comment: LaTeX, 4 pages, 5 figures; title slightly changed, explanations added
(16 pages, 14 figures), final version published in JHE
The Effect of Participation in Government Consortia on the R&D Productivity of Firms: A Case Study of Robot Technology in Japan
This paper examines the effect of participation in government-sponsored R&D consortia on the R&D productivity of firms in the case of robot technology in Japan. We attempt to provide a new empirical analysis and discussions on the issue of government project evaluation by using indicators of the quality of patents, by investigating the impact of the evolution of government programs, and comparing government-sponsored R&D consortia with collaborative R&D among firms. Using indicators of the quality of patents which enables us to provide an estimation of quality-adjusted research productivity, we find that participation in government programs has a positive impact on the research productivity of participating firms, but the impact of participation became much higher after the design of government programs in this field changed in the late 1990s. Also, we find that participation in government-sponsored consortia has a greater impact on research productivity than participation in collaborative R&D among firms. This may support government involvement in R&D as a coordinator of R&D collaboration.industrial policy, robot thchnology, Japanese innovation system, collaborative R&D
Particle Energization in an Expanding Magnetized Relativistic Plasma
Using a 2-1/2-dimensional particle-in-cell (PIC) code to simulate the
relativistic expansion of a magnetized collisionless plasma into a vacuum, we
report a new mechanism in which the magnetic energy is efficiently converted
into the directed kinetic energy of a small fraction of surface particles. We
study this mechanism for both electron-positron and electron-ion (mi/me=100, me
is the electron rest mass) plasmas. For the electron-positron case the pairs
can be accelerated to ultra-relativistic energies. For electron-ion plasmas
most of the energy gain goes to the ions.Comment: 7 pages text plus 5 figures, accepted for publication by Physical
Review Letter
Supersymetry on the Noncommutative Lattice
Built upon the proposal of Kaplan et.al. [hep-lat/0206109], we construct
noncommutative lattice gauge theory with manifest supersymmetry. We show that
such theory is naturally implementable via orbifold conditions generalizing
those used by Kaplan {\sl et.al.} We present the prescription in detail and
illustrate it for noncommutative gauge theories latticized partially in two
dimensions. We point out a deformation freedom in the defining theory by a
complex-parameter, reminiscent of discrete torsion in string theory. We show
that, in the continuum limit, the supersymmetry is enhanced only at a
particular value of the deformation parameter, determined solely by the size of
the noncommutativity.Comment: JHEP style, 1+22 pages, no figure, v2: two references added, v3:
three more references adde
Super Weyl Anomalies in the AdS/CFT Correspondence
Anomalies of N = (4,4) superconformal field theories coupled to a conformal
supergravity background in two dimensions are computed by using the AdS/CFT
correspondence. We find that Weyl, axial gauge and super Weyl transformations
are anomalous, while general coordinate, local Lorentz, vector gauge and local
super transformations are not. The coefficients of the anomalies show that the
superconformal field theories have the central charge expected in the AdS/CFT
correspondence.Comment: 16 pages, LaTeX, references added and typos correcte
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