3,450 research outputs found
Fibre Bundles and Generalised Dimensional Reduction
We study some geometrical and topological aspects of the generalised
dimensional reduction of supergravities in D=11 and D=10 dimensions, which give
rise to massive theories in lower dimensions. In these reductions, a global
symmetry is used in order to allow some of the fields to have a non-trivial
dependence on the compactifying coordinates. Global consistency in the internal
space imposes topological restrictions on the parameters of the
compactification as well as the structure of the space itself. Examples that we
consider include the generalised reduction of the type IIA and type IIB
theories on a circle, and also the massive ten-dimensional theory obtained by
the generalised reduction of D=11 supergravity.Comment: 23 pages, Late
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On defining partition entropy by inequalities
Partition entropy is the numerical metric of uncertainty within
a partition of a finite set, while conditional entropy measures the degree of
difficulty in predicting a decision partition when a condition partition is
provided. Since two direct methods exist for defining conditional entropy
based on its partition entropy, the inequality postulates of monotonicity,
which conditional entropy satisfies, are actually additional constraints on
its entropy. Thus, in this paper partition entropy is defined as a function
of probability distribution, satisfying all the inequalities of not only partition
entropy itself but also its conditional counterpart. These inequality
postulates formalize the intuitive understandings of uncertainty contained
in partitions of finite sets.We study the relationships between these inequalities,
and reduce the redundancies among them. According to two different
definitions of conditional entropy from its partition entropy, the convenient
and unified checking conditions for any partition entropy are presented, respectively.
These properties generalize and illuminate the common nature
of all partition entropies
Massive Three-Dimensional Supergravity From R+R^2 Action in Six Dimensions
We obtain a three-parameter family of massive N=1 supergravities in three
dimensions from the 3-sphere reduction of an off-shell N=(1,0) six-dimensional
Poincare supergravity that includes a curvature squared invariant. The
three-dimensional theory contains an off-shell supergravity multiplet and an
on-shell scalar matter multiplet. We then generalise this in three dimensions
to an eight-parameter family of supergravities. We also find a duality
relationship between the six-dimensional theory and the N=(1,0) six-dimensional
theory obtained through a T^4 reduction of the heterotic string effective
action that includes the higher-order terms associated with the
supersymmetrisation of the anomaly-cancelling \tr(R\wedge R) term.Comment: Latex, 32 Pages, an equation is corrected, a few new equations and a
number of clarifying remarks are adde
General Kerr-NUT-AdS Metrics in All Dimensions
The Kerr-AdS metric in dimension D has cohomogeneity [D/2]; the metric
components depend on the radial coordinate r and [D/2] latitude variables \mu_i
that are subject to the constraint \sum_i \mu_i^2=1. We find a coordinate
reparameterisation in which the \mu_i variables are replaced by [D/2]-1
unconstrained coordinates y_\alpha, and having the remarkable property that the
Kerr-AdS metric becomes diagonal in the coordinate differentials dy_\alpha. The
coordinates r and y_\alpha now appear in a very symmetrical way in the metric,
leading to an immediate generalisation in which we can introduce [D/2]-1 NUT
parameters. We find that (D-5)/2 are non-trivial in odd dimensions, whilst
(D-2)/2 are non-trivial in even dimensions. This gives the most general
Kerr-NUT-AdS metric in dimensions. We find that in all dimensions D\ge4
there exist discrete symmetries that involve inverting a rotation parameter
through the AdS radius. These symmetries imply that Kerr-NUT-AdS metrics with
over-rotating parameters are equivalent to under-rotating metrics. We also
consider the BPS limit of the Kerr-NUT-AdS metrics, and thereby obtain, in odd
dimensions and after Euclideanisation, new families of Einstein-Sasaki metrics.Comment: Latex, 24 pages, minor typos correcte
The double charm decays of Meson in the Perturbative QCD Approach
We make a systematic investigation on the double charm decays of meson,
by employing the perturbative QCD approach based on factorization. It is
found that the non-factorizable emission diagrams are not negligible in these
channels. We predict the branching ratios of these decays and also the
transverse polarization fractions of decays, % where V denote the vector meson.
We find that the magnitudes of the branching ratios of the decays
and are very close to
each other, which are well suited to extract the Cabibbo-Kobayashi-Maskawa
angle through the amplitude relations. In addition, a large transverse
polarization contribution that can reach is predicted in some of
the meson decay to two vector charmed mesons.Comment: 22 pages, 5 tables, to appear at PRD. arXiv admin note: text overlap
with arXiv:1112.125
Critical and Non-Critical Einstein-Weyl Supergravity
We construct N=1 supersymmetrisations of some recently-proposed theories of
critical gravity, conformal gravity, and extensions of critical gravity in four
dimensions. The total action consists of the sum of three separately off-shell
supersymmetric actions containing Einstein gravity, a cosmological term and the
square of the Weyl tensor. For generic choices of the coefficients for these
terms, the excitations of the resulting theory around an AdS_4 background
describe massive spin-2 and massless spin-2 modes coming from the metric;
massive spin-1 modes coming from a vector field in the theory; and massless and
massive spin-3/2 modes (with two unequal masses) coming from the gravitino.
These assemble into a massless and a massive N=1 spin-2 multiplet. In critical
supergravity, the coefficients are tuned so that the spin-2 mode in the massive
multiplet becomes massless. In the supersymmetrised extensions of critical
gravity, the coefficients are chosen so that the massive modes lie in a
"window" of lowest energies E_0 such that these ghostlike fields can be
truncated by imposing appropriate boundary conditions at infinity, thus leaving
just positive-norm massless supergravity modes.Comment: 29 page
Supersymmetry of the Schrodinger and PP Wave Solutions in Einstein-Weyl Supergravities
We obtain the Schrodinger and general pp-wave solutions with or without the
massive vector in Einstein-Weyl supergravity. The vector is an auxiliary field
in the off-shell supermultiplet and it acquires a kinetic term in the
Weyl-squared super invariant. We study the supersymmetry of these solutions and
find that turning on the massive vector has a consequence of breaking all the
supersymmetry. The Schrodinger and also the pp-wave solutions with the massive
vector turned off on the other hand preserve 1/4 of the supersymmetry.Comment: 13 pages, no figur
Similarity-Based Classification in Partially Labeled Networks
We propose a similarity-based method, using the similarity between nodes, to
address the problem of classification in partially labeled networks. The basic
assumption is that two nodes are more likely to be categorized into the same
class if they are more similar. In this paper, we introduce ten similarity
indices, including five local ones and five global ones. Empirical results on
the co-purchase network of political books show that the similarity-based
method can give high accurate classification even when the labeled nodes are
sparse which is one of the difficulties in classification. Furthermore, we find
that when the target network has many labeled nodes, the local indices can
perform as good as those global indices do, while when the data is sparce the
global indices perform better. Besides, the similarity-based method can to some
extent overcome the unconsistency problem which is another difficulty in
classification.Comment: 13 pages,3 figures,1 tabl
Study of color suppressed modes
The color suppressed modes are
analyzed in perturbative QCD approach. We find that the dominant contribution
is from the non-factorizable diagrams. The branching ratios calculated in our
approach for agree with current experiments. By
neglecting the gluonic contribution, we predict the branching ratios of are at the comparable size of , but smaller than that of .Comment: revtex, 5 pages, axodraw.st
New Einstein-Sasaki Spaces in Five and Higher Dimensions
We obtain infinite classes of new Einstein-Sasaki metrics on complete and
non-singular manifolds. They arise, after Euclideanisation, from BPS limits of
the rotating Kerr-de Sitter black hole metrics. The new Einstein-Sasaki spaces
L^{p,q,r} in five dimensions have cohomogeneity 2, and U(1) x U(1) x U(1)
isometry group. They are topologically S^2 x S^3. Their AdS/CFT duals will
describe quiver theories on the four-dimensional boundary of AdS_5. We also
obtain new Einstein-Sasaki spaces of cohomogeneity n in all odd dimensions
D=2n+1 \ge 5, with U(1)^{n+1} isometry.Comment: Revtex, 4 pages, metric regularity conditions are further refine
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