342 research outputs found
Non-SUSY -branes delocalized in two directions, tachyon condensation and T-duality
We here generalize our previous construction [hep-th/0409019] of
non-supersymmetric -branes delocalized in one transverse spatial direction
to two transverse spatial directions in supergravities in arbitrary dimensions
(). These solutions are characterized by five parameters. We show how these
solutions in interpolate between D()-anti-D() brane system,
non-BPS D-branes (delocalized in one direction) and BPS D-branes by
adjusting and scaling the parameters in suitable ways. This picture is very
similar to the descent relations obtained by Sen in the open string effective
description of non-BPS D brane and BPS D-brane as the respective
tachyonic kink and vortex solutions on the D-anti-D brane system
(with some differences). We compare this process with the T-duality
transformation which also has the effect of increasing (or decreasing) the
dimensionality of the branes by one.Comment: 19 pages, late
Intersecting non-SUSY -brane with chargeless 0-brane as black -brane
Unlike BPS -brane, non-supersymmetric (non-susy) -brane could be either
charged or chargeless. As envisaged in [hep-th/0503007], we construct an
intersecting non-susy -brane with chargeless non-susy -brane by taking
T-dualities along the delocalized directions of the non-susy -brane solution
delocalized in transverse directions (where ). In general
these solutions are characterized by four independent parameters. We show that
when the intersecting charged as well as chargeless non-susy -brane
with chargeless 0-brane can be mapped by a coordinate transformation to black
-brane when two of the four parameters characterizing the solution take some
special values. For definiteness we restrict our discussion to space-time
dimensions . We observe that parameters characterizing the black brane
and the related dynamics are in general in a different branch of the parameter
space from those describing the brane-antibrane annihilation process. We
demonstrate this in the two examples, namely, the non-susy D0-brane and the
intersecting non-susy D4 and D0-branes, where the solutions with the explicit
microscopic descriptions are known.Comment: 25 page
ADM masses for black strings and p-branes
An ADM mass formula is derived for a wide class of black solutions with
certain spherical symmetry. By applying this formula, we calculate the ADM
masses for recently discovered black strings and -branes in diverse
dimensions. By this, the Bogolmol'nyi equation can be shown to hold explicitly.
A useful observation is made for non-extremal black -branes that only for , i.e. for a black hole, can its ADM mass be read directly from the
asymptotic behaviour of the metric component .Comment: 9 pages, harvmac, CERN-TH.6877/93.(a typing error in eq. (3.2)
corrected
The open string pair-production rate enhancement by a magnetic flux
We extend the amplitude calculations of \cite{Lu:2009yx} to exhaust the
remaining cases for which one set of D branes carrying a flux (electric or
magnetic) is placed parallel at separation to the other set carrying also a
flux but with the two fluxes sharing at most one common field-strength index.
We then find that the basic structure of amplitudes remains the same when the
two fluxes share at least one common index but it is more general when the two
fluxes share no common index. We discuss various properties of the amplitudes
such as the large separation limit, the onset of various instabilities and the
open string pair production. In particular, when one flux is electric and weak
and the other is magnetic and fixed, we find that the open string pair
production rate is greatly enhanced by the presence of this magnetic flux when
the two fluxes share no common field-strength index and this rate becomes
significant when the separation is on the order of string scale.Comment: 33 pages, no figures, a few points refined to the published version
JHEP09(2009)09
On the low energy brane/anti-brane dynamics
We study the dynamical behavior of a pair of Dp-brane and anti Dp-brane () moving parallel to each other in the region where the brane and
anti-brane annihilation will not occur and the low energy description is valid.
Given this, we perform a general analysis, in the center of mass frame, of the
behavior of the effective potential with respect to the relative brane
separation and find that the classical orbits of this system are in general
unbound except for case for which classical bound orbits exist. The
non-linearity of the low energy DBI action for D-brane is important for the
underlying dynamics. We solve also the explicit orbits for case.Comment: 15 pages, 2 figures; shorten version published in Phys. Lett
An SL(2, Z) Multiplet of Type IIB Super Five-Branes
It is well-known that the low energy string theory admits a non-singular
solitonic super five-brane solution which is the magnetic dual to the
fundamental string solution. By using the symmetry of the type IIB string
theory, we construct an SL(2, Z) multiplet of magnetically charged super
five-branes starting from this solitonic solution. These solutions are
characterized by two integral three-form charges and are stable
when the integers are coprime. We obtain an expression for the tension of these
five-branes as envisaged by Witten. The SL(2, Z) multiplets of
black strings and black fivebranes and the existence of similar magnetic dual
solutions of strings in type II string theory in have also been
discussed.Comment: 13 pages, LaTeX, no figures, Eqs.(18)-(26) have been corrected, some
important changes have been made, replaces the withdrawn versio
On the determination of the dilaton-antisymmetric tensor couplings in supergravity theories
A new approach is provided to determine the dilaton--antisymmetric tensor
coupling in a supergravity theory by considering the static supersymmetric
field configuration around a super extended object, which is consistently
formulated in a curved superspace. By this, the corresponding SUSY
transformation rules can also be determined for vanishing fermionic fields as
well as bosonic fields other than those in the determined coupling. Therefore,
we can, in turn, use this determined part of the supergravity theory to study
all the related vacuum-like solutions. We have determined the
dilaton--antisymmetric tensor couplings, in which each of the antisymmetric
tensors is a singlet of the automorphism group of the corresponding
superalgebra, for every supergravity multiplet. This actually happens only for
supergravity theories, which agrees completely with the spin-content
analysis and the classified super -branes, therefore giving more
support to the existence of the fundamental Type II -branes. A prediction is
made of the supergravity which has not yet been written down so
far.Comment: 23 pages, harvmac, CERN-TH.6691/9
Fundamental strings and NS5-branes from unstable D-branes in supergravity
By using the non-supersymmetric -brane solutions delocalized in arbitrary
number of transverse directions in type II supergravities, we show how they can
be regarded as interpolating solutions between unstable D-branes (a non-BPS
D-brane or a pair of coincident D-brane-antiD-brane) and fundamental strings
and also between unstable D-branes and NS5-branes. We also show that some of
these solutions can be regarded as interpolating solutions between
NS5/5 and D-branes (for ). This gives a closed
string description of the tachyon condensation and lends support to the
conjecture that the open string theory on unstable D-branes at the tachyonic
vacuum has soliton solutions describing not only the lower dimensional BPS
D-branes, but also the fundamental strings as well as the NS5-branes.Comment: 11 pages, LaTeX, one statement corrected and one reference added, v3:
more details of the solution used is given, version to appear in Phys. Lett.
Non-SUSY -branes, bubbles and tubular branes
We consider non-supersymmetric -brane solutions of type II string theories
characterized by three parameters. When the charge parameter vanishes and one
of the other two takes a specific value, the corresponding chargeless solutions
can be regular and describe ``bubbles'' in static (unstable) equilibrium when
lifted to . In appropriate coordinates, they represent D6 branes with a
tubular topology R S when reduced to , called
the tubular D6 branes, held in static equilibrium by a fixed magnetic flux
(fluxbrane). Moreover, a `rotation parameter' can be introduced to either of
the above two eleven dimensional configurations, giving rise to a generalized
configuration labelling by the parameter. As such, it brings out the relations
among non-supersymmetric -branes, bubbles and tubular D6 branes. Given our
understanding on tubular D6 branes, we are able to reinforce the interpretation
of the chargeless non-supersymmetric -branes as representing
-brane-anti-brane (or non-BPS -brane) systems, and understand the
static nature and various singularities of these systems in a classical
supergravity approximation.Comment: 18 pages, footnote 7 removed due to some erro
Remarks on the instability of black Dp-branes
We show that for black D-branes having charge and Hawking temperature
, the product is bounded from above for and is
unbounded for . While the maximum occurs at some finite value of a
parameter for , it occurs at infinity of the parameter for . As
a consequence, for fixed charge, there are two black D-branes (for ) at any given temperature less than its maximum value, and when the
temperature is maximum there is one black D-brane. For , there is only
one black D5-brane at a given temperature less than its maximum value, whereas,
for , since there is no bound for the temperature, there is always a black
D6-brane solution at a given temperature. Of the two black D-branes (for
), one is large which is shown to be thermodynamically unstable and
the other is small which is stable. But for , the black D-branes are
always thermodynamically unstable. The stable, small black D-brane, however,
under certain conditions, can become unstable quantum mechanically and decay
either to a BPS D-brane or to a Kaluza-Klein "bubble of nothing" through
closed string tachyon condensation. The small D5, D6 branes, although
classically unstable, have the same fate under similar conditions.Comment: 12 pages, LaTeX, 1 figure, v2: minor clarifications added, v3: added
free energy calculation, version to appear in Phys. Lett.
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