335 research outputs found
The orbifold-string theories of permutation-type: II. Cycle dynamics and target space-time dimensions
We continue our discussion of the general bosonic prototype of the new
orbifold-string theories of permutation type. Supplementing the extended
physical-state conditions of the previous paper, we construct here the extended
Virasoro generators with cycle central charge
, where is the length of cycle
in twisted sector . We also find an equivalent, reduced formulation
of each physical-state problem at reduced cycle central charge
. These tools are used to begin the study of the target
space-time dimension of cycle in sector , which
is naturally defined as the number of zero modes (momenta) of each cycle. The
general model-dependent formulae derived here will be used extensively in
succeeding papers, but are evaluated in this paper only for the simplest case
of the "pure" permutation orbifolds.Comment: 32 page
Equivalence of partition functions for noncommutative U(1) gauge theory and its dual in phase space
Equivalence of partition functions for U(1) gauge theory and its dual in
appropriate phase spaces is established in terms of constrained hamiltonian
formalism of their parent action. Relations between the electric--magnetic
duality transformation and the (S) duality transformation which inverts the
strong coupling domains to the weak coupling domains of noncommutative U(1)
gauge theory are discussed in terms of the lagrangian and the hamiltonian
densities. The approach presented for the commutative case is utilized to
demonstrate that noncommutative U(1) gauge theory and its dual possess the same
partition function in their phase spaces at the first order in the
noncommutativity parameter \theta .Comment: 15 pages. Version to appear in JHE
The Orbifold-String Theories of Permutation-Type: III. Lorentzian and Euclidean Space-Times in a Large Example
To illustrate the general results of the previous paper, we discuss here a
large concrete example of the orbifold-string theories of permutation-type. For
each of the many subexamples, we focus on evaluation of the \emph{target
space-time dimension} , the \emph{target space-time
signature} and the \emph{target space-time symmetry} of each cycle in each
twisted sector . We find in particular a gratifying \emph{space-time
symmetry enhancement} which naturally matches the space-time symmetry of each
cycle to its space-time dimension. Although the orbifolds of
-permutation-type are naturally Lorentzian, we find that the target
space-times associated to larger permutation groups can be Lorentzian,
Euclidean and even null (\hat{D}_{j}(\sigma)=0), with varying space-time
dimensions, signature and symmetry in a single orbifold.Comment: 36 page
Understanding Terrorist Organizations with a Dynamic Model
Terrorist organizations change over time because of processes such as
recruitment and training as well as counter-terrorism (CT) measures, but the
effects of these processes are typically studied qualitatively and in
separation from each other. Seeking a more quantitative and integrated
understanding, we constructed a simple dynamic model where equations describe
how these processes change an organization's membership. Analysis of the model
yields a number of intuitive as well as novel findings. Most importantly it
becomes possible to predict whether counter-terrorism measures would be
sufficient to defeat the organization. Furthermore, we can prove in general
that an organization would collapse if its strength and its pool of foot
soldiers decline simultaneously. In contrast, a simultaneous decline in its
strength and its pool of leaders is often insufficient and short-termed. These
results and other like them demonstrate the great potential of dynamic models
for informing terrorism scholarship and counter-terrorism policy making.Comment: To appear as Springer Lecture Notes in Computer Science v2:
vectorized 4 figures, fixed two typos, more detailed bibliograph
Towards Deconstruction of the Type D (2,0) Theory
We propose a four-dimensional supersymmetric theory that deconstructs, in a
particular limit, the six-dimensional theory of type . This 4d
theory is defined by a necklace quiver with alternating gauge nodes
and . We test this proposal by comparing the
6d half-BPS index to the Higgs branch Hilbert series of the 4d theory. In the
process, we overcome several technical difficulties, such as Hilbert series
calculations for non-complete intersections, and the choice of
versus gauge groups. Consistently, the result matches the Coulomb
branch formula for the mirror theory upon reduction to 3d
Twisted Open Strings from Closed Strings: The WZW Orientation Orbifolds
Including {\it world-sheet orientation-reversing automorphisms}
in the orbifold program, we construct the operator
algebras and twisted KZ systems of the general WZW {\it orientation orbifold}
. We find that the orientation-orbifold sectors corresponding
to each are {\it twisted open} WZW strings, whose
properties are quite distinct from conventional open-string orientifold
sectors. As simple illustrations, we also discuss the classical (high-level)
limit of our construction and free-boson examples on abelian .Comment: 65 pages, typos correcte
Nonabelian Monopoles from Matrices: Seeds of the Spacetime Structure
We study the expectation value of (the product) of the one-particle projector
(s) in the reduced matrix model and matrix quantum mechanics in general. This
quantity is given by the nonabelian Berry phase: we discuss the relevance of
this with regard to the spacetime structure. The case of the USp matrix model
is examined from this respect. Generalizing our previous work, we carry out the
complete computation of this quantity which takes into account both the nature
of the degeneracy of the fermions and the presence of the space time points
belonging to the antisymmetric representation. We find the singularities as
those of the SU(2) Yang monopole connection as well as the pointlike
singularities in 9+1 dimensions coming from its SU(8) generalization. The
former type of singularities, which extend to four of the directions lying in
the antisymmetric representations, may be regarded as seeds of our four
dimensional spacetime structure and is not shared by the IIB matrix model. From
a mathematical viewpoint, these connections can be generalizable to arbitrary
odd space dimensions due to the nontrivial nature of the eigenbundle and the
Clifford module structure.Comment: 29 pages, Latex, 1 epsf figur
Aspects of Puff Field Theory
We describe some features of the recently constructed "Puff Field Theory,"
and present arguments in favor of it being a field theory decoupled from
gravity. We construct its supergravity dual and calculate the entropy of this
theory in the limit of large 't Hooft coupling. We also determine the leading
irrelevant operator that governs its deviation from N=4 super Yang-Mills
theory.Comment: 31 pages, 1 figur
Compactification in the Lightlike Limit
We study field theories in the limit that a compactified dimension becomes
lightlike. In almost all cases the amplitudes at each order of perturbation
theory diverge in the limit, due to strong interactions among the longitudinal
zero modes. The lightlike limit generally exists nonperturbatively, but is more
complicated than might have been assumed. Some implications for the matrix
theory conjecture are discussed.Comment: 13 pages, 3 epsf figures. References and brief comments added.
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