77 research outputs found
D-branes and orientifolds of SO(3)
We study branes and orientifolds on the group manifold of SO(3). We consider
particularly the case of the equatorial branes, which are projective planes. We
show that a Dirac-Born-Infeld action can be defined on them, although they are
not orientable. We find that there are two orientifold projections with the
same spacetime action, which differ by their action on equatorial branes.Comment: 11 pages, no figure, uses JHEP3.cls. V2 : minor correction
Effective Potential on Fuzzy Sphere
The effective potential of quantized scalar field on fuzzy sphere is
evaluated to the two-loop level. We see that one-loop potential behaves like
that in the commutative sphere and the Coleman-Weinberg mechanism of the
radiatively symmetry breaking could be also shown in the fuzzy sphere system.
In the two-loop level, we use the heavy-mass approximation and the
high-temperature approximation to perform the evaluations. The results show
that both of the planar and nonplanar Feynman diagrams have inclinations to
restore the symmetry breaking in the tree level. However, the contributions
from planar diagrams will dominate over those from nonplanar diagrams by a
factor N^2. Thus, at heavy-mass limit or high-temperature system the quantum
field on the fuzzy sphere will behave like those on the commutative sphere. We
also see that there is a drastic reduction of the degrees of freedom in the
nonplanar diagrams when the particle wavelength is smaller than the
noncommutativity scale.Comment: Latex 18 pages, some typos correcte
Grafting and Poisson structure in (2+1)-gravity with vanishing cosmological constant
We relate the geometrical construction of (2+1)-spacetimes via grafting to
phase space and Poisson structure in the Chern-Simons formulation of
(2+1)-dimensional gravity with vanishing cosmological constant on manifolds of
topology , where is an orientable two-surface of genus
. We show how grafting along simple closed geodesics \lambda is
implemented in the Chern-Simons formalism and derive explicit expressions for
its action on the holonomies of general closed curves on S_g. We prove that
this action is generated via the Poisson bracket by a gauge invariant
observable associated to the holonomy of . We deduce a symmetry
relation between the Poisson brackets of observables associated to the Lorentz
and translational components of the holonomies of general closed curves on S_g
and discuss its physical interpretation. Finally, we relate the action of
grafting on the phase space to the action of Dehn twists and show that grafting
can be viewed as a Dehn twist with a formal parameter satisfying
.Comment: 43 pages, 10 .eps figures; minor modifications: 2 figures added,
explanations added, typos correcte
On the 2D zero modes' algebra of the SU(n) WZNW model
A quantum group covariant extension of the chiral parts of the
Wess-Zumino-Novikov-Witten model on a compact Lie group G gives rise to two
matrix algebras with non-commutative entries. These are generated by "chiral
zero modes" which combine in the 2D model into "Q-operators" which encode
information about the internal symmetry and the fusion ring. We review earlier
results about the SU(n) WZNW Q-algebra and its Fock representation for n=2 and
display the first steps towards their generalization to higher n.Comment: 10 pages, Talk presented by L.H. at the International Workshop LT10
(17-23 June 2013, Varna, Bulgaria
Geometrical (2+1)-gravity and the Chern-Simons formulation: Grafting, Dehn twists, Wilson loop observables and the cosmological constant
We relate the geometrical and the Chern-Simons description of
(2+1)-dimensional gravity for spacetimes of topology , where
is an oriented two-surface of genus , for Lorentzian signature and general
cosmological constant and the Euclidean case with negative cosmological
constant. We show how the variables parametrising the phase space in the
Chern-Simons formalism are obtained from the geometrical description and how
the geometrical construction of (2+1)-spacetimes via grafting along closed,
simple geodesics gives rise to transformations on the phase space. We
demonstrate that these transformations are generated via the Poisson bracket by
one of the two canonical Wilson loop observables associated to the geodesic,
while the other acts as the Hamiltonian for infinitesimal Dehn twists. For
spacetimes with Lorentzian signature, we discuss the role of the cosmological
constant as a deformation parameter in the geometrical and the Chern-Simons
formulation of the theory. In particular, we show that the Lie algebras of the
Chern-Simons gauge groups can be identified with the (2+1)-dimensional Lorentz
algebra over a commutative ring, characterised by a formal parameter
whose square is minus the cosmological constant. In this
framework, the Wilson loop observables that generate grafting and Dehn twists
are obtained as the real and the -component of a Wilson loop
observable with values in the ring, and the grafting transformations can be
viewed as infinitesimal Dehn twists with the parameter .Comment: 50 pages, 6 eps figure
Brane Bulk Couplings and Condensation from REA Fusion
The physical meaning of the Reflection Equation Algebras of hep-th/0107265
and hep-th/0203110 is elucidated in the context of Wess--Zumino--Witten D-brane
geometry, as determined by couplings of closed-string modes to the D-brane.
Particular emphasis is laid on the role of algebraic fusion of the matrix
generators of the Reflection Equation Algebras. The fusion is shown to induce
transitions among D-brane configurations admitting an interpretation in terms
of RG-driven condensation phenomena.Comment: 13 pages; an essentially re-structured version of the paper to appear
in JHE
Expanded Strings in the Background of NS5-branes via a M2-brane, a D2-brane and D0-branes
Classical configurations of a M2-brane, a D2-brane and D0-branes are
investigated in the background of an infinite array of M5-branes or NS5-branes.
On the M2-brane, we discuss three kinds of configurations, such as a sphere, a
cylinder and a torus-like one. These are stabilized by virtue of the background
fluxes of M5-branes. The torus-like M2-brane configuration has winding and
momentum numbers of 11th direction, and in terms of the type IIA superstring
theory, this corresponds to a torus-like D2-brane with electric and magnetic
fluxes on it. We also reproduce the same configuration from a non-abelian
Born-Infeld action for D0-branes. It will be a construction of closed strings
from D0-branes. An electric flux quantization condition on the D2-brane is also
discussed in terms of D0-branes.Comment: 33 pages, 6 figures, references and footnote added, confusing
expressions and introduction are improved, version to appear in JHE
Anomalous Hydrodynamics
Our goal is to examine the role of anomalies in the hydrodynamic regime of
field theories. We employ methods based on gauge/gravity duality to examine
R-charge anomalies in the hydrodynamic regime of stronly t'Hooft coupled, large
N, N = 4 Super Yang-Mills. We use a single particle spectrum treatment based on
the familiar "level crossing" picture of chiral anomalies to investigate
thermalized, massless QED. In each case, we work in the presence of a
homogeneous background magnetic field, and find the same result. Regardless of
whether a paricular current is anomalously non-conserved or not, as long as it
participates in an anomalous 3-pt. correlator, its constitutive relation
recieves a new term, proportional to a product of the anomaly coefficient, the
magnetic field, and any charge density participating in the anomaly. This
agrees with results found by Alekseev et.al. for QED. We include a general,
symmetry based argument for the presence of such terms, and use linear response
theory to determine their coefficients in a model with anomalous global
charges. This last method we apply to briefly examine baryon transport in
chiral QCD in a strong magnetic field.Comment: 23 pages, 2 figures. To be submitted to JHE
Boundary three-point function on AdS2 D-branes
Using the H3+-Liouville relation, I explicitly compute the boundary
three-point function on AdS2 D-branes in H3+, and check that it exhibits the
expected symmetry properties and has the correct geometrical limit. I then find
a simple relation between this boundary three-point function and certain fusing
matrix elements, which suggests a formal correspondence between the AdS2
D-branes and discrete representations of the symmetry group. Concluding
speculations deal with the fuzzy geometry of AdS2 D-branes, strings in the
Minkowskian AdS3, and the hypothetical existence of new D-branes in H3+.Comment: 27 pages, v2: significant clarifications added in sections 4.3 and
A Note on Thermodynamics and Holography of Moving Giant Gravitons
In our previous work (Phys. Rev. D63, 085010, hep-th/0011290), we showed that
the brane universe on the giant graviton moving in the near-horizon background
of the dilatonic D(6-p)-brane is described by the mirage cosmology. We study
thermodynamic properties of the moving giant graviton by applying
thermodynamics of cosmology and the recently proposed holographic principles of
cosmology. We find that the Fischler-Susskind holographic bound is satisfied by
the closed brane universe on the moving giant graviton with p>3. The Bekenstein
and the Hubble entropy bounds and the recently proposed Verlinde's holographic
principle applied to the brane universe on the giant graviton are also studied.Comment: 13 pages, LaTeX, revised version to appear in Phys. Rev.
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