1,512 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
R^2 Corrections for 5D Black Holes and Rings
We study higher-order corrections to two BPS solutions of 5D supergravity,
namely the supersymmetric black ring and the spinning black hole. Due in part
to our current relatively limited understanding of F-type terms in 5D
supergravity, the nature of these corrections is less clear than that of their
4D cousins. Effects of certain terms found in Calabi-Yau compactification
of M-theory are specifically considered. For the case of the black ring, for
which the microscopic origin of the entropy is generally known, the
corresponding higher order macroscopic correction to the entropy is found to
match a microscopic correction, while for the spinning black hole the
corrections are partially matched to those of a 4D black hole.Comment: 9 page
Superconformal Black Hole Quantum Mechanics
In recent work, the superconformal quantum mechanics describing D0 branes in
the AdS_2xS^2xCY_3 attractor geometry of a Calabi-Yau black hole with D4 brane
charges p^A has been constructed and found to contain a large degeneracy of
chiral primary bound states. In this paper it is shown that the asymptotic
growth of chiral primaries for N D0 branes exactly matches the
Bekenstein-Hawking area law for a black hole with D4 brane charge p^A and D0
brane charge N. This large degeneracy arises from D0 branes in lowest Landau
levels which tile the CY_3xS^2 horizon. It is conjectured that such a multi-D0
brane CFT1 is holographically dual to IIA string theory on AdS_2xS^2xCY_3.Comment: 8 page
On the covariance of the Dirac-Born-Infeld-Myers action
A covariant version of the non-abelian Dirac-Born-Infeld-Myers action is
presented. The non-abelian degrees of freedom are incorporated by adjoining to
the (bosonic) worldvolume of the brane a number of anticommuting fermionic
directions corresponding to boundary fermions in the string picture. The
proposed action treats these variables as classical but can be given a matrix
interpretation if a suitable quantisation prescription is adopted. After
gauge-fixing and quantisation of the fermions, the action is shown to be in
agreement with the Myers action derived from T-duality. It is also shown that
the requirement of covariance in the above sense leads to a modified WZ term
which also agrees with the one proposed by Myers.Comment: 18 pages. Minor alterations to the text; references adde
Scaling issues in ensemble implementations of the Deutsch-Jozsa algorithm
We discuss the ensemble version of the Deutsch-Jozsa (DJ) algorithm which
attempts to provide a "scalable" implementation on an expectation-value NMR
quantum computer. We show that this ensemble implementation of the DJ algorithm
is at best as efficient as the classical random algorithm. As soon as any
attempt is made to classify all possible functions with certainty, the
implementation requires an exponentially large number of molecules. The
discrepancies arise out of the interpretation of mixed state density matrices.Comment: Minor changes, reference added, replaced with publised versio
Unsolvability of the Halting Problem in Quantum Dynamics
It is shown that the halting problem cannot be solved consistently in both
the Schrodinger and Heisenberg pictures of quantum dynamics. The existence of
the halting machine, which is assumed from quantum theory, leads into a
contradiction when we consider the case when the observer's reference frame is
the system that is to be evolved in both pictures. We then show that in order
to include the evolution of observer's reference frame in a physically sensible
way, the Heisenberg picture with time going backwards yields a correct
description.Comment: 4 pages, 3 figure
Multi giant graviton systems, SUSY breaking and CFT
In this article, we describe giant gravitons in AdS_5 x S^5 moving along
generic trajectories in AdS_5. The giant graviton dynamics is solved by proving
that the D3-brane effective action reduces to that of a massive point particle
in AdS_5 and therefore the solutions are in one to one correspondence with
timelike geodesics of AdS_5. All these configurations are related via
isometries of the background, which induce target space symmetries in the world
volume theory of the D-brane. Hence, all these configurations preserve the same
amount of supersymmetry as the original giant graviton, i.e. half of the
maximal supersymmetry. Multiparticle configurations of two or more giant
gravitons are also considered. In particular, a binary system preserving one
quarter of the supersymmetries is found, providing a non trivial time-dependent
supersymmetric solution. A short study on the dual CFT description of all the
above states is given, including a derivation of the exact induced isometry map
in the CFT side of the correspondence.Comment: latex, 27+1 pages. v2: comment on mixing of states in section 4.3
added, reference added, typos corrected, final versio
The baryon vertex with magnetic flux
In this letter we generalise the baryon vertex configuration of AdS/CFT by
adding a suitable instantonic magnetic field on its worldvolume, dissolving
D-string charge. A careful analysis of the configuration shows that there is an
upper bound on the number of dissolved strings. This should be a manifestation
of the stringy exclusion principle. We provide a microscopical description of
this configuration in terms of a dielectric effect for the dissolved strings.Comment: 17 pages, 2 figures. V2: reference added. V3: version to appear in
JHE
M-Theory Giant Gravitons with C field
We find giant graviton configurations of an M5-brane probe in the D=11
supergravity background generated by a stack of non-threshold (M2,M5) bound
states. The M5-brane probe shares three directions with the background and
wraps a two-sphere transverse to the bound states. For a particular value of
the worldvolume gauge field of the PST formalism, there exist solutions of the
equations of motion for which the M5-brane probe behaves as a wave propagating
in the (M2,M5) background. We have checked that the probe breaks the
supersymmetry of the background exactly as a massless particle moving along the
trajectory of its center of mass.Comment: 11 pages, LaTeX; v2: references adde
D0-branes in Black Hole Attractors
Configurations of N probe D0-branes in a Calabi-Yau black hole are studied. A
large degeneracy of near-horizon bound states are found which can be described
as lowest Landau levels tiling the horizon of the black hole. These states
preserve some of the enhanced supersymmetry of the near-horizon AdS_2xS^2xCY
attractor geometry, but not of the full asymptotically flat solution.
Supersymmetric non-abelian configurations are constructed which, via the Myers
effect, develop charges associated with higher-dimensional branes wrapping CY
cycles. An SU(1,1|2) superconformal quantum mechanics describing D0-branes in
the attractor geometry is explicitly constructed.Comment: 27 page
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