9,447 research outputs found
Some aspects of calculating flows about three-dimensional subsonic inlets
Various three dimensional inlet models were calculated based on the potential flow model. Results are presented in the forms of surface static pressure, flow angularity, surface flow pattern, and inlet flow field. It is indicated that the extension of the lower lip can reduce the adverse pressure gradient and increase the flow separation bound
The Chern-Simons Coefficient in Supersymmetric Non-abelian Chern-Simons Higgs Theories
By taking into account the effect of the would be Chern-Simons term, we
calculate the quantum correction to the Chern-Simons coefficient in
supersymmetric Chern-Simons Higgs theories with matter fields in the
fundamental representation of SU(n). Because of supersymmetry, the corrections
in the symmetric and Higgs phases are identical. In particular, the correction
is vanishing for N=3 supersymmetric Chern-Simons Higgs theories. The result
should be quite general, and have important implication for the more
interesting case when the Higgs is in the adjoint representation.Comment: more references and explanation about rgularization dpendence are
included, 13 pages, 1 figure, latex with revte
Covariant gaussian approximation in Ginzburg - Landau model
Condensed matter systems undergoing second order transition away from the
critical fluctuation region are usually described sufficiently well by the mean
field approximation. The critical fluctuation region, determined by the
Ginzburg criterion, , is narrow even
in high superconductors and has universal features well captured by the
renormalization group method. However recent experiments on magnetization,
conductivity and Nernst effect suggest that fluctuations effects are large in a
wider region both above and below . In particular some "pseudogap"
phenomena and strong renormalization of the mean field critical temperature
can be interpreted as strong fluctuations effects that are
nonperturbative (cannot be accounted for by "gaussian fluctuations"). The
physics in a broader region therefore requires more accurate approach. Self
consistent methods are generally "non - conserving" in the sense that the Ward
identities are not obeyed. This is especially detrimental in the symmetry
broken phase where, for example, Goldstone bosons become massive. Covariant
gaussian approximation remedies these problems. The Green's functions obey all
the Ward identities and describe the fluctuations much better. The results for
the order parameter correlator and magnetic penetration depth of the Ginzburg -
Landau model of superconductivity are compared with both Monte Carlo
simulations and experiments in high cuprates.Comment: 24 pages, 7 figure
Signature of Schwinger's pair creation rate via radiation generated in graphene by strong electric current
Electron - hole pairs are copuously created by an applied electric field near
the Dirac point in graphene or similar 2D electronic systems. It was shown
recently that for sufficiently large electric fields and ballistic times the
I-V characteristics become strongly nonlinear due to Schwinger's pair creation.
Since there is no energy gap the radiation from the pairs' annihilation is
enhanced. The spectrum of radiation is calculated. The angular and polarization
dependence of the emitted photons with respect to the graphene sheet is quite
distinctive. For very large currents the recombination rate becomes so large
that it leads to the second Ohmic regime due to radiation friction.Comment: 9 pages, 7 figure
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