510 research outputs found
Supersymmetric and Kappa-invariant Coincident D0-Branes
We propose a generic supersymmetric and kappa-invariant action for describing
coincident D0-branes with non-abelian matter fields on their worldline. The
action is shown to be in agreement with the Matrix Theory limit of the
ND0-brane effective action.Comment: JHEP style, 1+8 page
Universal Holographic Chiral Dynamics in an External Magnetic Field
In this work we further extend the investigation of holographic gauge
theories in external magnetic fields, continuing earlier work. We study the
phenomenon of magnetic catalysis of mass generation in 1+3 and 1+2 dimensions,
using D3/D7- and D3/D5-brane systems, respectively. We obtain the low energy
effective actions of the corresponding pseudo Goldstone bosons and study their
dispersion relations. The D3/D7 system exhibits the usual
Gell-Mann--Oakes--Renner (GMOR) relation and a relativistic dispersion
relation, while the D3/D5 system exhibits a quadratic non-relativistic
dispersion relation and a modified linear GMOR relation. The low energy
effective action of the D3/D5 system is related to that describing magnon
excitations in a ferromagnet. We also study properties of general Dp/Dq systems
in an external magnetic field and verify the universality of the magnetic
catalysis of dynamical symmetry breaking.Comment: 41 pages, 11 figures, references adde
Caged Black Holes: Black Holes in Compactified Spacetimes II - 5d Numerical Implementation
We describe the first convergent numerical method to determine static black
hole solutions (with S^3 horizon) in 5d compactified spacetime. We obtain a
family of solutions parametrized by the ratio of the black hole size and the
size of the compact extra dimension. The solutions satisfy the demanding
integrated first law. For small black holes our solutions approach the 5d
Schwarzschild solution and agree very well with new theoretical predictions for
the small corrections to thermodynamics and geometry. The existence of such
black holes is thus established. We report on thermodynamical (temperature,
entropy, mass and tension along the compact dimension) and geometrical
measurements. Most interestingly, for large masses (close to the
Gregory-Laflamme critical mass) the scheme destabilizes. We interpret this as
evidence for an approach to a physical tachyonic instability. Using
extrapolation we speculate that the system undergoes a first order phase
transition.Comment: 42 pages, 19 eps figures; v2: 3 references added, version to appear
in Phys.Rev.
BPS Electromagnetic Waves on Giant Gravitons
We find new 1/8-BPS giant graviton solutions in , carrying
three angular momenta along , and investigate their properties.
Especially, we show that nonzero worldvolume gauge fields are admitted
preserving supersymmetry. These gauge field modes can be viewed as
electromagnetic waves along the compact D3 brane, whose Poynting vector
contributes to the BPS angular momenta. We also analyze the (nearly-)spherical
giant gravitons with worldvolume gauge fields in detail. Expressing the
in Hopf fibration ( fibred over ), the wave propagates along the
fiber.Comment: 25 pages, no figures, v2: references adde
Hot Defect Superconformal Field Theory in an External Magnetic Field
In this paper we investigate the influence of an external magnetic field on a
flavoured holographic gauge theory dual to the D3/D5 intersection at finite
temperature. Our study shows that the external magnetic field has a freezing
effect on the confinement/ deconfinement phase transition. We construct the
corresponding phase diagram. We investigate some thermodynamic quantities of
the theory. A study of the entropy reveals enhanced relative jump of the
entropy at the "chiral" phase transition. A study of the magnetization shows
that both the confined and deconfined phases exhibit diamagnetic response. The
diamagnetic response in the deconfined phase has a stronger temperature
dependence reflecting the temperature dependence of the conductivity. We study
the meson spectrum of the theory and analyze the stability of the different
phases looking at both normal and quasi-normal semi-classical excitations. For
the symmetry breaking phase we analyze the corresponding pseudo-Goldstone modes
and prove that they satisfy non-relativistic dispersion relation.Comment: 42 pages, 14 figure
Black Hole Statistics from Holography
We study the microstates of the ``small'' black hole in the \half-BPS
sector of AdS, the superstar of Myers and Tafjord, using the
powerful holographic description provided by LLM. The system demonstrates the
inherently statistical nature of black holes, with the geometry of Myer and
Tafjord emerging only after averaging over an ensemble of geometries. The
individual microstate geometries differ in the highly non-trivial topology of a
quantum foam at their core, and the entropy can be understood as a partition of
units of flux among 5-cycles, as required by flux quantization. While the
system offers confirmation of the most controversial aspect of Mathur and
Lunin's recent ``fuzzball'' proposal, we see signs of a discrepancy in
interpreting its details.Comment: 21 pages, 4 figures; References adde
Spontaneous heavy cluster emission rates using microscopic potentials
The nuclear cluster radioactivities have been studied theoretically in the
framework of a microscopic superasymmetric fission model (MSAFM). The nuclear
interaction potentials required for binary cold fission processes are
calculated by folding in the density distribution functions of the two
fragments with a realistic effective interaction. The microscopic nuclear
potential thus obtained has been used to calculate the action integral within
the WKB approximation. The calculated half lives of the present MSAFM
calculations are found to be in good agreement over a wide range of observed
experimental data.Comment: 4 pages, 4 figure
The (p,q) String Tension in a Warped Deformed Conifold
We find the tension spectrum of the bound states of p fundamental strings and
q D-strings at the bottom of a warped deformed conifold. We show that it can be
obtained from a D3-brane wrapping a 2-cycle that is stabilized by both electric
and magnetic fluxes. Because the F-strings are Z_M-charged with non-zero
binding energy, binding can take place even if (p,q) are not coprime.
Implications for cosmic strings are briefly discussed.Comment: 17 pages, 1 figur
Caged Black Holes: Black Holes in Compactified Spacetimes I -- Theory
In backgrounds with compact dimensions there may exist several phases of
black objects including the black-hole and the black-string. The phase
transition between them raises puzzles and touches fundamental issues such as
topology change, uniqueness and Cosmic Censorship. No analytic solution is
known for the black hole, and moreover, one can expect approximate solutions
only for very small black holes, while the phase transition physics happens
when the black hole is large. Hence we turn to numerical solutions. Here some
theoretical background to the numerical analysis is given, while the results
will appear in a forthcoming paper. Goals for a numerical analysis are set. The
scalar charge and tension along the compact dimension are defined and used as
improved order parameters which put both the black hole and the black string at
finite values on the phase diagram. Predictions for small black holes are
presented. The differential and the integrated forms of the first law are
derived, and the latter (Smarr's formula) can be used to estimate the ``overall
numerical error''. Field asymptotics and expressions for physical quantities in
terms of the numerical ones are supplied. Techniques include ``method of
equivalent charges'', free energy, dimensional reduction, and analytic
perturbation for small black holes.Comment: 23 pages. v3: version to be published in PRD, 3 references adde
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