20,184 research outputs found
(m,n)-String-Like Dp-Brane Bound States
An (m, n)-string bound state (with m, n relatively prime integers) in type
IIB string theory can be interpreted from the D-string worldsheet point of view
as n D-strings carrying m units of quantized electric flux or quantized
electric field. We argue, from the D-brane worldvolume point of view, that
similar Dp-brane bound states should also exist for in both
type IIA (when is even) and type IIB (when is odd) string theories. As
in case, these bound states can each be interpreted as Dp-branes
carrying m units of quantized constant electric field. In particular, they all
preserve one half of the spacetime supersymmetries.Comment: 16 pages, Revtex, typos corrected and references adde
((F, D1), D3) Bound State and Its T-dual Daughters
In the previous paper [hep-th/9904129], we constructed a general explicit BPS
solution for (F, D3) non-threshold bound state. By using the SL(2,Z) symmetry
of type IIB string theory, we here construct from (F, D3) a more general BPS
configuration for a D3 brane with certain units of quantized 5-form flux and an
infinite number of parallel (F, D1)-strings. We study its decoupling limit and
find that given Maldacena's correspondence with respect to simple
D3 branes and with the usual string coupling, we should have a similar
correspondence with respect to this bound state but now with an effective
string coupling. We discuss possible descendants of this bound state by
T-dualities along its longitudinal or transverse directions. In particular, we
present explicit configurations for ((F, Dp), D(p + 2)) bound states for . All these configurations preserve one half of the spacetime
supersymmetries.Comment: 27 pages; Improved discussion on AdS/CFT correspondence, discussion
on extra bound states added, and more references adde
4-string Junction and Its Network
We study a BPS configuration in which four strings (of different type) meet
at a point in supergravity, i.e., the low energy effective
theory of -compactified type II string theory. We demonstrate that the
charge conservation of the four strings implies the vanishing of the net force
(due to the tensions of various strings) at the junction and vice versa, using
the tension formula for strings obtained recently by the present
authors. We then show that a general 4-string junction preserves 1/8 of the
spacetime supersymmetries. Using 4-string junctions as building blocks, we
construct a string network which also preserves 1/8 of the spacetime
supersymmetries.Comment: 15 pages, Late
Supergravity approach to tachyon condensation on the brane-antibrane system
We study the tachyon condensation on the D-brane--antiD-brane system from the
supergravity point of view. The non-supersymmetric supergravity solutions with
symmetry ISO() SO() are known to be characterized by three
parameters. By interpreting this solution as coincident D-branes and
-branes we give, for the first time, an explicit
representation of the three parameters of supergravity solutions in terms of
and the tachyon vev. We demonstrate that the solution and the
corresponding ADM mass capture all the required properties and give a correct
description of the tachyon condensation advocated by Sen on the
D-brane--antiD-brane system.Comment: 9 page
On 1/4 BPS ((F, D1), (NS5, D5)) bound states of type IIB string theory
We construct two new SL(2,Z) invariant vacua of type IIB string theory which
are bound states of strings with 5-branes, written as ((F, D1),
(NS5, D5)) and preserve 1/4 of the full space-time supersymmetries. For the
first case, the strings live inside the 5-brane world-volume and in the second
case the strings are perpendicular to the 5-brane world-volume. In the first
case, naively one would expect an attractive interaction between the strings
and the 5-branes due to attractive force between F and D5 and also between D1
and NS5. We find that 1/4 BPS bound state exists only when the vacuum moduli
satisfy certain condition which is found to be consistent with the no-force
condition between the branes. No such complication arises for the second case.
The tension formulae and the various other descendant states which can be
obtained by the application of T-duality for both these bound states are
discussed.Comment: 22 pages, 1 table, minor changes and one reference added, the version
to appear in JHE
Optical analogue of spontaneous symmetry breaking induced by tachyon condensation in amplifying plasmonic arrays
We study analytically and numerically an optical analogue of tachyon
condensation in amplifying plasmonic arrays. Optical propagation is modeled
through coupled-mode equations, which in the continuous limit can be converted
into a nonlinear one-dimensional Dirac-like equation for fermionic particles
with imaginary mass, i.e. fermionic tachyons. We demonstrate that the vacuum
state is unstable and acquires an expectation value with broken chiral
symmetry, corresponding to the homogeneous nonlinear stationary solution of the
system. The quantum field theory analogue of this process is the condensation
of unstable fermionic tachyons into massive particles. This paves the way for
using amplifying plasmonic arrays as a classical laboratory for spontaneous
symmetry breaking effects in quantum field theory.Comment: 5 pages, 5 figure
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