27,899 research outputs found
On the Covariant Quantization of the 2nd-Ilk Superparticle
This paper is devoted to the quantization of the second-ilk superparticle
using the Batalin-Vilkovisky method. We show the full structure of the master
action. By imposing gauge conditions on the gauge fields rather than on
coordinates we find a gauge-fixed quantum action which is free. The structure
of the BRST charge is exhibited and the BRST cohomology yields the same
physical spectrum as the light- cone quantization of the usual superparticle.Comment: 17 page
Massive Gravity on a Non-extremal Brane
We consider a brane world scenario which arises as the near-horizon region of
a non-extremal D5-brane. There is a quasi-localized massive graviton mode, as
well as harmonic modes of higher mass which are bound to the brane to a lesser
degree. Lorentz invariance is slightly broken, which may have observable
effects due to the leakage of the metastable graviton states into the bulk.
Unlike a brane world arising from an extremal D5-brane, there is no mass gap.
We also find that a brane world arising from a non-extremal M5/M5-brane
intersection has the same graviton dynamics as that of a non-extremal D5-brane.
This is evidence that a previously conjectured duality relation between the
dual quantum field theories of each p-brane background may hold away from
extremality.Comment: 10 pages, 4 figures, LaTe
Synthesis of oxyanion-doped barium strontium cobaltferrites: stabilization of the cubic perovskite and enhancement in conductivity
In this paper we demonstrate the successful incorporation of oxyanions (borate, phosphate) into Ba1ySryCo0.8Fe0.2O3−δ (BSCF) cathode materials. For low levels of dopant, a small enhancement in the conductivity was observed; e.g. 31.6, 34.4 and 35.9 S·cm-1 for Ba0.33Sr0.67Co0.8Fe0.2O3−δ, Ba0.33Sr0.67Co0.76Fe0.19B0.05O3−δ and Ba0.33Sr0.67Co0.76Fe0.19P0.05O3−δ, respectively, at 700ºC. Most significantly, oxyanion doping was shown to improve the stability of the cubic form of BSCF at intermediate temperatures (especially for P-doping), helping to prevent the transition to a hexagonal cell, and maintaining its excellent electrical properties. The work shows the potential of oxyanion doping strategies to modify the performance of SOFC cathode materials
S^1-wrapped D3-branes on Conifolds
We construct a D3-brane wrapped on S^1, which is fibred over the resolved
conifold as its transverse space. Whereas a fractional D3-brane on the resolved
conifold is not supersymmetric and has a naked singularity, our solution is
supersymmetric and regular everywhere. We also consider an -wrapped
D3-brane on the resolved cone over T^{1,1}/Z_2, as well as on the deformed
conifold. In the former case, we obtain a regular supergravity dual to a
certain four-dimensional field theory whose Lorentz and conformal symmetries
are broken in the IR region and restored in the UV limit.Comment: Latex, 14 pages, minor correction
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