110,488 research outputs found
Gaussian Effective Potential and the Coleman's normal-ordering Prescription : the Functional Integral Formalism
For a class of system, the potential of whose Bosonic Hamiltonian has a
Fourier representation in the sense of tempered distributions, we calculate the
Gaussian effective potential within the framework of functional integral
formalism. We show that the Coleman's normal-ordering prescription can be
formally generalized to the functional integral formalism.Comment: 6 pages, revtex; With derivation details and an example added. To
appear in J. Phys.
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
Diffraction of a pulse by a three-dimensional corner
Three dimensional diffraction of sonic booms by corners of structure
Smooth Cosmologies from M-theory
We review two ways in which smooth cosmological evolution between two de
Sitter phases can be obtained from M/string-theory. Firstly, we perform a
hyperbolic reduction of massive IIA* theory to D=6 N=(1,1) SU(2)xU(1) gauged de
Sitter supergravity, which supports smooth cosmological evolution between dS_4
x S^2 and a dS_6-type geometry. Secondly, we obtain four-dimensional de Sitter
gravity with SU(2) Yang-Mills gauge fields from a hyperbolic reduction of
standard eleven-dimensional supergravity. The four-dimensional theory supports
smooth cosmological evolution between dS_2 x S^2 and a dS_4-type geometry.
Although time-dependent, these solutions arise from a first-order system via a
superpotential construction. For appropriate choices of charges, these
solutions describe an expanding universe whose expansion rate is significantly
larger in the past than in the future, as required for an inflationary model.Comment: Latex, 7 pages, Contribution to Quantum Theory and Symmetries
Non-singular Twisted S-branes From Rotating Branes
We show that rotating p-brane solutions admit an analytical continuation to
become twisted Sp-branes. Although a rotating p-brane has a naked singularity
for large angular momenta, the corresponding S-brane configuration is regular
everywhere and exhibits a smooth bounce between two phases of Minkowski
spacetime. If the foliating hyperbolic space of the transverse space is of even
dimension, such as for the twisted SM5-brane, then for an appropriate choice of
parameters the solution smoothly flows from a warped product of two-dimensional
de Sitter spacetime, five-dimensional Euclidean space and a hyperbolic 4-space
in the infinite past to Minkowski spacetime in the infinite future. We also
show that non-singular S-Kerr solutions can arise from higher-dimensional Kerr
black holes, so long as all (all but one) angular momenta are non-vanishing for
even (odd) dimensions.Comment: Latex, 20 page
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