Giant tachyons in the landscape
Giant tachyons in the landscape
Iosif Bena 0 2 3
Mariana Grana 0 2 3
Stanislav Kuperstein 0 2 3
Stefano Massai 0 1 3
F- 0 3
Gif-sur-Yvette 0 3
France 0 3
Open Access 0 3
c The Authors. 0 3
0 Theresienstr. 37, 80333 Mu nchen , Germany
1 Arnold Sommerfeld Center for Theoretical Physics
2 Institut de Physique Th eorique, CEA Saclay , CNRS URA 2306
3  I. Bena , M. Gran a, S. Kuperstein and S. Massai, Anti-D3 Branes: Singular to the bitter end
We study the dynamics of localized and fully backreacting anti-D3 branes at the tip of the Klebanov-Strassler geometry. We use a non-supersymmetric version of the Polchinski-Strassler analysis to compute the potential for anti-D3 branes to polarize into all kinds of five-brane shells in all possible directions. We find that generically there is a direction along which the brane-brane interaction is repulsive, which implies that anti-D3 branes are tachyonic. Hence, even though anti-D3 branes can polarize into five-branes, the solution will most likely be unstable. This indicates that anti-D3 brane uplift may not result in stable de Sitter vacua.
AdS-CFT Correspondence; dS vacua in string theory; D-branes
2 Localized anti-D3 branes at the tip of the deformed conifold
3 The Polchinski-Strassler analysis of anti-brane polarization
4 The NS5 polarization potential and the tachyon
5 Conclusions and future directions A Review of the non-supersymmetric Polchinski-Strassler polarization B The complex components of the three-form at the North Pole 1
Generic string theory flux compactifications with stabilized moduli yield four-dimensional
spacetimes with a negative cosmological constant, and adding anti-D3 branes to regions of
high warp factor in these compactifications is one of the most generic methods to uplift
the cosmological constant and produce a landscape of de Sitter vacua in String Theory .
Indeed, the prototypical example of a region with D3 brane charge dissolved in fluxes is the
Klebanov-Strassler (KS) warped deformed conifold solution  and probe anti-D3 branes
in this background have been argued by Kachru, Pearson and Verlinde (KPV)  to give
rise to metastable configurations that describe metastable vacua of the KS gauge theory.
This intuition was challenged by the fact that the supergravity solution describing
backreacting anti-D3 branes in the Klebanov-Strassler solution must have a certain singularity
in the infrared, both when the anti-D3 branes are smeared on the S3 at the bottom of
the deformed conifold , and also when they are localized . Furthermore, it was
shown that this singularity cannot be cloaked with a black hole horizon [9, 10], nor via
polarization into D5 branes at a finite distance away from the KS tip . Thus, all the
calculations that have been done so far, which a-priori could have given either a positive
or a negative or an undetermined answer about this singularity being physical, have given
(via some rather nontrivial mechanisms) a negative answer.
It is important to stress that all previous works have been focused on studying
properties of the anti-D3 brane supergravity solution, while the true solution which is believed
to be dual to a metastable state in the KS theory is the one corresponding to anti-D3
branes polarized into NS5 branes at the tip of the KS geometry. Thus, one may argue that
the infrared singularities simply signal that essential infrared physics has been ignored, as
common for gravity duals of non-conformal and less supersymmetric theories.
It is the purpose of this paper to elucidate this infrared physics. Our final result is that
the anti-D3 branes can polarize into NS5 and many other types of (p, q) 5-branes wrapping
various two-spheres at the bottom of the KS solution. However, to our great surprise,
we find that the theory describing these anti-D3 branes has a tachyonic instability which
indicates that the polarized vacua will not be metastable but unstable. This in turn would
imply that the de Sitter vacua obtained by uplifting with anti-branes will be unstable.
Our strategy for arriving to this result is to analyze the physics of anti-D3 branes that
are localized at the North Pole of the S3 at the bottom of the KS solution and to argue that
these anti-D3 branes source an AdS5 S5 throat perturbed with RR and NS-NS three-form
the physics of these anti-branes can be captured by a non-supersymmetric version of the
Polchinski-Strassler analysis .1
At first glance, computing the appropriate relevant perturbations of this AdS5 S5
throat seems to be an unattainable goal, since the fully backreacted solution with localized
anti-D3 branes in KS (which is a non-supersymmetric solution that depends on more than
ten functions of two variables) is impossible to obtain analytically with current technology.
However, we find a way to overcome this problem by using the fully back-reacted solution
with smeared anti-D3 branes we constructed in  and several key ingredients of the
Polchinski-Strassler construction. First we use the potential of smeared anti-D3 branes to
polarize into D5 branes wrapping the contractible S2 of the deformed conifold at a finite
distance away from the tip to calculate the polarization potential for localized anti-D3
branes in the same channel. Second, we decompose the self-dual part of the three-form
flux near the North Pole in (1, 2) and (3, 0) components, and use this to express the various
quantities appearing in this potential in terms of fermion and boson bilinear deformations
of the Lagrangian of the dual gauge theory. Third, we use these deformations to calculate
the polarization potential of localized anti-D3 branes into NS5 branes wrapping a
twosphere inside the large three-sphere of the deformed conifold, as well as the potential felt
by a probe anti-D3 brane in this background. We find that for generic parameters there is
always some direction along which this potential is negative, which indicates that anti-D3
branes in KS are tachyonic.
The D3-D5 polarization potential we are starting from depends on two parameters
that cannot be fixed unless one constructs the full non-linear solution that interpolates
between the infrared with anti-branes and the Klebanov-Strassler ultraviolet (this has been
performed only at linearized level in ). However, in the final potential that we obtain
the dependence on these two parameters drops out. Hence, our result is very robust, and
is independent of the details of the gluing between the IR and UV regions.
Our result is in our opinion the definitive answer to the question of what is the fate of
anti-D3 branes in the Klebanov-Strassler solution, and the physics it reveals fits perfectly
with all the other results that have been obtained when studying fully-backreacted
antibrane solutions. Indeed, one does not expect tachyonic brane configurations to give rise to
the context of five-dimensional gauged supergravity see .
a singularity that can be cloaked by a horizon, and this agrees with the absence of smooth
negatively-charged black holes in KS, both smeared [9, 16] and localized . Second, an
unstable brane can give rise to a supergravity solution that correctly captures the energy
and expectation values of the corresponding unstable vacuum. This explains why the
various calculations done using the perturbative anti-D3 brane solutions [5, 1720] yielded
(rather non-trivially) the energy and VEVs one would expect from a solution with
antibranes. Third, the presence of a tachyon does not eliminate brane polarization - on the
contrary, it makes it more likely along the tachyonic direction. This agrees with the fact
that there exist supersymmetric and stable polarized D6-D8 configurations in AdS space
with negative D6 charge [21, 22]. However, for supersymmetry breaking anti-D3 branes
in flat space, the fact that the theory that describes the polarizing branes is tachyonic
indicates that the polarized configurations will have either instabilities or a very low life
time, and therefore they will not give rise to long-lived metastable vacua of the type needed
for building cosmological models.
There are two frequent misconceptions when trying to understand the relation between
our work on the supergravity backreaction of a stack of ND3 anti-D3 branes and the KPV
calculation that finds that probe anti-D3 branes can polarize into long-lived metastable
NS5 branes. The first is that our calculation is done in the regime of parameters when the
anti-D3 branes backreact, gsND3
1, while the KPV calculation ignores the backreaction
of the anti-D3 branes and thus it can only be valid in the opposite regime of parameters,
1; hence, since metastability is not robust under changing the parameters of
the solution, one may hope that a small number of anti-D3 branes polarized into NS5
branes can still give rise to a metastable vacuum, which may go away as gs is increased.
Nevertheless, this is not so: the KPV probe potential is derived by S-dualizing both the
probe and the background, and considering the polarization of anti-D3 branes into D5
branes in the S-dual of the KS solution. However, in the KS duality frame, in order to
have a polarized anti-D3 shell with NS5 dipole charge, the mass of the anti-D3 branes
in their tension, this only happens if gsND3
1, and this is precisely the regime where
our supergravity analysis is valid. Our results indicate that extrapolating the results of the
KPV probe calculation performed at gsND3
KS solution misses essential physics.
The other misconception is that the KPV extrapolated probe calculation only finds a
metastable vacuum with NS5 brane dipole charge one when the ratio between the number of
anti-D3 branes and the flux of the deformed conifold, ND3/M , is less than about 8%, while
our calculation, as we will discuss in detail later, is valid in the regime of parameters when
ND3 > M . This is again a red herring, since one can do equally well a KPV calculation
in which the NS5 dipole charge, pNS5, is bigger then one and find that this calculation
implies that there should exist metastable vacua for ND3 < 0.08M pNS5, which is compatible
with the regime in which we work and in which the tachyons are present. Hence, the
extrapolated probe calculation misses the tachyonic terms in the regime where it overlaps
with our calculation, and there is therefore no reason to trust it. Thus, the only regime of
parameters where one can describe correctly anti-D3 branes polarized into NS5 branes in
KS is the backreacted regime.
1 to describe D3-NS5 polarization in the
This paper is organized as follows. In section 2 we discuss the physics of the solution
sourced by anti-D3 branes that are either smeared or localized at the bottom of the KS
background. In section 3 we briefly review how the Polchinski-Strassler analysis can be
applied to our situation, and in section 4 we read off the three parameters in the polarization
potential of the anti-D3 branes and reconstruct the polarization potential in all possible
channels. In particular we find that generically there always exists a direction along which
probe anti-D3 branes are repelled, which indicates that anti-D3 branes have a tachyonic
instability. In section 5 we discuss the implications of this instability for the physics
of anti-branes and present conclusions. Appendix A is devoted to a review of the
nonsupersymmetric Polchinski-Strassler construction. Appendix B contains the expansion of
the RR and NS-NS three-form field strengths near the North Pole and the calculation of
the ratio of the gaugino mass to the supersymmetric fermionic mass in the dual theory.
Localized anti-D3 branes at the tip of the deformed conifold
In this section we will describe in more detail the strategy outlined in the Introduction,
to study the dynamics of localized anti-D3 branes at the tip of the Klebanov-Strassler
The Klebanov-Strassler (KS) solution  is a supersymmetric warped solution based
on the deformed conifold . This is a six-dimensional deformed cone over the five
dimenRR three-form flux. The three-form fluxes of the solution combine in the complex form
G3 = F3 (C0 + ie)H3 which is imaginary self-dual (ISD). See for example  for a
review of the KS geometry.
We consider anti-D3 branes localized at one point on the large S3 at the tip of this
solution, which we refer to as the North Pole (NP). The deformed conifold is everywhere
regular and, in particular, the vicinity of the NP locally looks like R6. The backreaction
of anti-D3s is therefore expected to create an AdS5 S5 throat with a radius determined
by the number of anti-branes, which we will denote throughout the paper by ND3. The
configuration is depicted in figure 1. This configuration preserves one SU(2) factor of the
total SU(2) SU(2) isometry group of the deformed conifold (see, for example, [25, 26]).
The AdS5 S5 throat created by the anti-D3s is glued to the ambient KS geometry,
and hence it will be perturbed by modes coming from the bulk. Most of these modes will
be irrelevant in the infrared, but some will not. In particular, since the anti-D3 branes
preserve different supersymmetries from the KS solution, the ISD three-form flux of KS
will enter the throat and create non-normalizable, relevant perturbations that correspond
precisely the situation that was considered in the work of Polchinski and Strassler (PS) .
The main focus of this paper was on supersymmetric three-form flux perturbations of
2A similar situation was described in  where, however, the effects of supersymmetry breaking were
not taken into account.
of the 3-sphere at the bottom of the deformed conifold. The imaginary self-dual (ISD) flux leaking
into the throat becomes singular in the deep IR. We investigate the possible resolutions of this
singularity by the polarization of the anti-D3 branes into D5, NS5 and other (p, q) 5-branes.
the bulk perturbations will explicitly break all the supersymmetries of the anti-D3 throat,
and hence we need to perform a non-supersymmetric PS analysis (similar to the one in 
and the last section of ). We explain this construction in all details in appendix A.
In the deep infrared the Polchinski-Strassler flux perturbations become important and
can destroy the AdS geometry, giving rise to a singularity . This is in line with the fact
that the anti-D3 brane singularity found in the smeared and linearized solution  is not
an artefact of linearization [6, 7] nor of the smearing .3 When the flux perturbations
are supersymmetric, Polchinski and Strassler have shown that this singularity is resolved
by the polarization of the 3-branes via the Myers dielectric effect  into shells of (p, q)
five-branes, that are in one-to-one correspondence to the vacua of the dual mass-deformed
N = 4 SYM theory .
Our purpose is to find whether the anti-D3 singularity can get similarly cured by the
polarization of the D3 branes into (p, q)-five-branes with different orientations. As we
explained in the Introduction, the direct route to investigate this is to solve the equations
of motion to find the backreacted solution with localized supersymmetry-breaking sources,
but we are not doing this. The only assumption we make is that the localized anti-D3 branes
will create a flux-perturbed AdS5S5 throat. Note that this assumption is minimal - if such
a throat does not exist than the anti-brane solution should be disregarded as unphysical.
One of the possible polarization channels inside this throat is the one corresponding to
an NS5 brane wrapping a 2-sphere inside the S3 of the deformed tip, depicted in figure 1.
This channel was analyzed in the probe approximation (i.e. neglecting the backreaction
of the anti-branes on the geometry) by KPV  and found to give rise to a locally stable
configuration. Our analysis does not ignore the backreaction of the anti-D3 branes that
polarize, and one of our purposes is to determine what happens to the KPV NS5 channel
if one takes this backreaction into account.
3The singularity of the smeared anti-brane solution is actually milder then that of localized anti-branes:
indeed the smeared solution still has anti-D3 form because the singular fields are weaker than the fields
of the smeared anti-D3 branes. On the other hand, when the anti-D3 branes are localized the singular
fields become much stronger than the anti-D3 fields, and completely destroy the AdS5 S5 structure in the
Another possible polarization channel is the orthogonal one, corresponding to D3
branes polarized into D5 branes wrapping the shrinking S2 of the deformed conifold at a
finite distance away from the tip (depicted also in figure 1). As we will explain in detail
below, the fact that this polarization takes place in a plane transverse to the S3 allows
one to compute exactly the fully backreacted polarization potential of localized anti-D3
branes by relating it to the polarization potential of smeared anti-D3 branes we computed
in . This latter potential does not have any minima, which indicates that the effects of
supersymmetry breaking are strong-enough to disable the D3D5 polarization channel of
the Polchinski-Strassler analysis. The purpose of the next section is to adapt the
PolchinskiStrassler analysis to anti-D3 branes in KS and to investigate the effects of supersymmetry
breaking for the NS5 polarization channel and for the oblique ones.
The Polchinski-Strassler analysis of anti-brane polarization
One of the most important results of the supersymmetric Polchinski-Strassler analysis is
that the polarization potentials corresponding to different polarization channels are
determined only by the UV boundary conditions that specify the relevant perturbations of the
dual theory, and not by the details of the infrared geometry created by the polarized branes.
Indeed, one can find the polarization potentials of the various types of branes by treating
the RR and NSNS three-form field strengths dual to fermion masses as small perturbations
of the original AdS5 S5 throat, and expanding the action of a probe five-brane in the
perturbed geometry. It then turns out that, rather surprisingly, these terms are completely
insensitive of the details of the infrared geometry and are solely determined by the UV
Hence, to compute the polarization potentials that determine the vacua of the theory,
one can simply probe the geometry sourced by un-polarized D3 branes. The potential
for five-branes probing the fully backreacted polarized brane background is guaranteed
to be exactly the same.4 It is very important to stress that this fact does not rely on
supersymmetry, and hence it will be true also when considering relevant perturbations
that break N = 4 to N = 0.
This analysis can be applied straightforwardly to anti-branes localized at the North
Pole of the S3 in the infrared of the KS solution. We introduce complex coordinates zi
6 close to the North Pole and parameterize the location and orientation of all
is a unit real 3-vector parametrizing the SO(3)-rotated S2 inside the S5. The radius of the
solution m and m0 correspond to the (1, 2) and (3, 0) components of the non-normalizable
complex three-form field strength that perturb the AdS5 S5 throat5 [36, 37] and the
4An explicit check of this can be found in  for solutions with M2 branes polarized into M5 branes [34, 35].
5From now on we choose the complex structure to have the same conventions as in , despite the fact
that we have an anti-D3 and not a D3 throat. Hence, we will always refer to the polarizing fields as (1, 2)
the 20 of SO(6). The full polarization potential is [12, 28]:
V(p,q) (z) =
where ND3 is the number of anti-D3 branes and M is the mass parameter of the (p, q)
by the gluing between the region where the anti-D3 branes dominate the geometry and
the asymptotically-KS UV. Since the only known solution with fully backreacted anti-D3
branes corresponds to smeared sources over the S3 at the tip of the deformed conifold ,
one can try to ask what happens to the various channels of the localized anti-D3 solution
when we smear the branes.
The shape of the gluing region (see figure 2) (which we will imprecisely refer to as
gluing surface) between the two regions depends on the position of the sources and
on their number. Indeed, the more anti-branes we have, the larger their Schwarzschild
radius will be, and the further out the gluing surface will be pushed. Furthermore, when
the anti-D3 branes are smeared on the S3 at the tip of the deformed conifold, this surface
corresponds to a constant radial coordinate slicing, while for a generic localized distribution
of branes this surface will not respect the SU(2) SU(2) invariance and will change its
shape. Therefore, it looks like the non-normalizable modes may change when the branes
are smeared or un-smeared and the shape of this surface changes. Nevertheless, we can
always work in a regime of parameters where this change will be negligible: if the number of
D3s is large enough, their Schwarzschild radius can be pushed away from the tip, and for
l the effects of moving the anti-brane sources on the shape of the gluing surface and
hence on the asymptotic value of the non-normalizable modes will be power-law suppressed.
Armed with this, we can go ahead and argue that smearing of the anti-D3 branes on
the S3 will not affect the polarization potential for D5 branes wrapping the shrinking S2 of
the deformed conifold, which happens in a plane orthogonal to the S3. In fact, moving the
anti-D3 branes around the tip will affect the warp factor as well as H3 and F3. However,
the cubic term in the polarization potential (3.1) is determined by the combination:
which is both closed and co-closed (d3+ = d ?6 3+ = 0), and therefore it is completely
determined by its asymptotic value. Hence m and m0 do not change when the anti-D3
branes are moved. Similarly, the quadratic term has three contributions. Two of them,
proportional to m2 and m02 come from the backreaction of the three-forms, and are present
also when the polarization is supersymmetric. Hence, they are completely determined by
m and m0 and therefore are not affected by the smearing. The third term, parameterized
mode is harmonic it also depends only on the data on the gluing surface. Hence, in the
regime of parameters in which we are working, the polarization potential for the transverse
D5 channel is not affected by the smearing of anti-D3 branes on the three-sphere.6
By using this fact, we can circumvent the problem of directly computing the NS5 and
oblique polarization potentials, which require the knowledge of the fully localized
antibrane solution. We will instead use the polarization potential for the D5 channel, which
we computed in  using the smeared solution, to determine the relation between m, m0
Since we do not know the non-linear solution corresponding to smeared backreacting
anti-D3 branes that interpolates between the IR and the UV (this is only known at linear
level ) our strategy is to use the most general solution sourced by anti-D3 branes
compatible with the SU(2) SU(2) symmetries of the Klebanov-Strassler background . This
solution is parameterized by two parameters bf and bk and we will relate them to the three
need only be determined up to an overall scale, and we will therefore only need two
relations to determine them. One such relation can be obtained directly from the transverse
polarization potential computed in . To obtain the second relation we will use the fact
that the closed ISD form decomposes into a (3, 0) and a (1, 2) component with respect to
the conifold complex structure. From the point of view of the anti-D3 brane throat at the
North Pole, the (3, 0) component is non-supersymmetric, and therefore corresponds in the
boundary theory to the gaugino mass m0. Similarly, the (1, 2) component corresponds to
the supersymmetric Polchinski-Strassler fermion mass, parameterized by m. Hence, the
which is enough to determine all the terms in the polarization potential.
The only condition needed to relate the D5 and the NS5 polarization potentials is
that the polarization radii are sufficiently small compared to the radius of the blown-up
3-sphere. This can be done either by making the 3-sphere large enough or by increasing the
D5 and NS5 dipole charge of the polarized shell, whose effect is to decrease its radius. Since
the relation between the parameters bf and bk that determine the anti-D3 solution and the
probe with large-enough dipole charge such that its polarization potential is unaffected by
the curvature of the 3-sphere and which can therefore be used to obtain this relation.
In the next section we will explicitly perform the computation we outlined above. A
surprise awaits: the result we get is completely independent of the two integration constants
bf and bk that determine the solution, and hence it does not depend at all on the gluing
which determines the UV boundary conditions of the perturbed anti-D3 AdS5 S5 throat.
We will thus be able to derive a universal result regarding all polarization channels.
6As we will explain in appendix A, other channels, in which the anti-D3 branes polarize into five-branes
extended along the smearing direction (such as the KPV NS5 channel explored in ) are wiped out by the
for localized (left) and smeared sources (center). On the other hand, for a large Schwarzschild radius
(right), the surface is once again SU(2) SU(2) invariant and the mass parameters are independent
of the anti-branes position at the tip.
The NS5 polarization potential and the tachyon
In this section we determine the polarization potential (3.1) for the NS5 and the oblique
the NS5 and the D5 channels correspond respectively to z in (3.1) being purely real and
purely imaginary. This is no longer true when supersymmetry is broken (an NS5 may have
directions as the NS5 and the D5 channels. For the two directions the SO(3)-invariant
polarization potential (3.1) will be of the form:
under the rescaling both of the full potential and of the coordinate R:
This quantity will be useful in relating the data of the anti-D3 brane conifold solution to the
For the D5 channel, the parameters a2, a3 and a4 in (4.1) were computed in  by
solving in the infrared the equations of motion for the most general ansatz compatible with
the symmetries of smeared anti-D3 branes. Since the solution was not glued to the UV
Klebanov-Strassler asymptotic solution, two integration constants for the flux functions,
called bf and bk, were not fixed. In principle these two parameters are not independent
and the precise relation between them could be determined in the UV by gluing to the KS
solution or to one of its non-normalizable deformations [38, 39]. However, as we will see
below, the physics is completely independent of the details of the UV. The potential in
terms of these constants is (see (5.4) of ):
Strassler solution can be found from (3.1) with Rez = 0:
2 = 4
+ (bf 4bk) (dz1 dz2 dz3 + dz1 dz2 dz3 + dz1 dz2 dz3) 3 + O
In order to proceed we need to relate the parameters bf and bk appearing in (4.4) to
the masses m and m0. This can be done by computing the components of the three-form
this we expand the deformed conifold metric around the North Pole, we choose a complex
structure for the resulting R
6 metric, and we read off the (1, 2) and the (3, 0) components
the details of this calculation to appendix B, and we just state here the final result:
h1 (?6G3 + iG3) | North Pole = 4i (bf + 12bk) dz1 dz2 dz3
Importantly not only the ratio appears to be real but so does each of the two masses, which
confirms the assumption we made in deriving equation (4.5).
NS5 channel. Plugging (4.4) and (4.10) into (4.8) we arrive at our first key result:
This implies that the quadratic term in the polarization potential for this channel vanishes,8
and hence we have:
The ratio of the gaugino mass to the supersymmetric mass of the other three fermions
is given by the ratio of the (3, 0) and (1, 2) parts of this three-form (see equation (35) in 
for m1,2,3 = m and m4 = m0). This implies that:
deeper and more surprising. As explained in detail in appendix A, this term in the potential
represents the force felt by a mobile anti-D3 brane in the background, and its vanishing in
the KPV probe calculation reflects the fact that the KS background has an SU(2) SU(2)
symmetry and therefore a single probe does not feel a force when moving on S3. Our
calculation, however, gives the force that a probe anti-D3 brane feels in the backreacted
supergravity solution sourced by a very large number of anti-D3 branes localized at the
North Pole. Since this background breaks the isometry of the three-sphere, one expects in
general that probe anti-D3 branes should feel a force in this background. The fact that
they do not, which comes after a highly non-trivial calculation, is very surprising. Even
more surprisingly, this conclusion does not depend on the precise relation between the
parameters bf and bk, or in other words it is insensitive to the UV asymptotics.
This result has a very important consequence, as it implies that there exists a direction
along which anti-D3 branes feel a repulsive force. To see this consider the polarization
potential into (p, q) five-branes wrapping a two-sphere in an oblique plane, parameterized
by the phase of z. The fact that the quadratic term for the NS5 channel (purely real z)
vanishes implies, from (4.7):
7We refer to Footnote 5 for our conventions regarding the complex structure.
and hence the coefficient of the quadratic term along a general oblique channel is:
2 Re(z) + Re
2 Im(z)iIm(z) ,
2 is given in (4.13).9 The crucial observation is
2 6= 0, there always exists a range of z such that a2 is negative:
Hence, in general there will always exist some oblique directions for which the
polarization potential has a negative quadratic term. Since this term gives also the potential
between unpolarized branes on the Coulomb branch, this result implies that a probe
antibrane in the AdS5 S5 throat created by the backreacting anti-branes will be repelled
towards the UV along that direction. As we have already advertised in the Introduction,
this establishes that backreacted anti-D3 branes at the tip of the KS conifold geometry have
a tachyonic mode. Furthermore, this result is independent of the integration constants bf
and bk, which indicates that the tachyon cannot be eliminated by playing with the KS UV
Conclusions and future directions
The fact that anti-D3 branes placed in the Klebanov-Strassler geometry are tachyonic
appears to be a very robust feature of their physics. Indeed, the calculation and the details
of the polarization potential and the ratios of m and m0 depend on the parameters bf and
bk that determine the gluing of the Klebanov-Strassler UV with the anti-brane-dominated
infrared, and one might have expected on general grounds that the force between the
antibranes also depends on these parameters. However, as we have seen, the presence of this
This result is further supported by the presence of a tachyon  when anti-M2 branes
are added to a background with M2 brane charge dissolved in fluxes . In fact,
that result appears to be stronger than the one we obtained here. The repulsion between
anti-M2 branes is manifest both when they move in an oblique direction as well as on the
sphere at the tip, while anti-D3 branes can move on the sphere with no force and only feel a
repulsive force when moving off-diagonally. The reason behind this is that the four-sphere
at the bottom of the CGLP geometry is not a four-cycle on the seven-dimensional base,
and the most general anti-M2 brane solution constructed in  allows for a change of the
integral of the four-form around this four-sphere, which is not topologically protected. If
one turns off this mode one finds that the potential between two anti-M2 branes is also flat
along the S4 at the bottom at the solution, as we found for anti-D3 branes. When one turns
this mode back on, the strength of the tachyon increases by the square of the coefficient
D5 channel (Re(z) = 0), since Re(2) < 0. Interestingly, a2 = 0 also for Re(z)/Im(z) = Re
of this mode. This again confirms our intuition that the tachyon is a generic feature of
the physics of anti-branes in backgrounds with charge dissolved in fluxes, that cannot be
removed by playing with the parameters of the supergravity solution. It would be clearly
important to confirm this explicitly by extending our analysis to other backgrounds with
charge dissolved in fluxes, both with anti-D3 and with other anti-brane charges [10, 4448].
An interesting future direction is to determine whether there is any way to see this
tachyon by performing a KPV-like probe calculation. As we explained in the Introduction,
anti-D3 branes only polarize into NS5 branes when gsND3
1, which is precisely the regime
of parameters that our supergravity backreacted calculation captures. Nevertheless, one
may consider the polarization of anti-D3 branes into D5 branes wrapping an S2 inside
the S3 at the bottom of the solution that is obtained by S-dualizing the KS solution, and
this polarization can happen in the regime of parameters gsND3
1, where the D5 brane
DBI action used in KPV is not invalidated by large gsND3 effects. If our result about
the tachyon is universal, this tachyon should be visible in this regime as well. Since the
coefficient of the tachyon is proportional to the square of the three-form field strength,
this tachyon would probably come out from terms in the brane action that are quadratic
in the supergravity fields, and hence are not captured by the DBI action. It would be
very interesting to identify these terms and see whether they give rise to a tachyon. The
outcome would be interesting either way: if a tachyon exists this implies that one has to
reconsider many non-supersymmetric brane probe calculations done using the Born-Infeld
action and see whether these calculations are invalidated by the presence of the terms that
give rise to a tachyon. If a tachyon does not exist this would reveal the first instance in
string theory where a tachyon goes away when changing duality frames, which would a
highly unusual and hence very exciting result.
Since our calculation is valid in the regime of parameters where the number of anti-D3
branes is large (ND3 > M 2) and the gluing surface is far-away from the KS tip, one can ask
whether our results will persist when the number of anti-branes is smaller than M 2. The
regime ND3 < M 2 was considered in , which studied the polarization potential outside
the anti-D3-dominated region and ignored the effects of the supersymmetry breaking on
the quadratic term of this potential (which, as we saw in this paper, are responsible for
the tachyon). To ascertain the presence of a tachyon in the regime ND3 < M 2, one has to
include the effects of the SO(3)-breaking harmonics sourced by the localized anti-D3 branes.
This was done for D3 branes in [25, 49], but here the calculation will be more involved
because of the broken supersymmetry. However, the robustness of the calculations done so
far, that reveal the omnipresence of tachyons in anti-brane solutions, makes it unlikely in
our opinion that the tachyon will go away.
Another feature that is important to understand is what is the endpoint of the
tachyonic instability. Indeed, our calculation reveals the existence of a tachyon that manifests
itself by the repulsion of anti-brane probes by backreacted anti-branes localized at the
North Pole, but does not allow us to track what happens after the anti-branes are repelled
outside of the near-North-Pole region. A similar (brane-brane repulsion) tachyon exists in
AdS5 solutions constructed in Type 0 string theory  and possibly also in
supergravity solutions corresponding to non-BPS branes ; if there is any relation between those
tachyons and ours this would help in understanding its endpoint.
It is also important to elucidate what are the implications of this tachyon for the
stability of the configurations where the anti-D3 branes polarize into NS5 branes wrapping
an S2 inside the S3. Indeed, our tachyon does not affect the existence of a minimum in
the NS5 polarization channel, and appears even to encourage brane polarization along the
oblique directions in equation (4.15). However, the fact that the inter anti-D3 potential is
now repulsive implies that the D3-NS5 polarized configurations will not be long lived and
will most likely be unstable. Indeed, the repulsive potential makes the tunneling barrier
for shooting out an anti-D3 brane from the polarized shell very shallow. Another possible
effect of the tachyon is to cause a non-spherical (ellipsoidal) instability in the polarized
shells . Hence, such a construction will not give a long-lived de Sitter vacuum, but will
either give an unstable one or one whose cosmological constant will jump down whenever
the anti-D3 branes are shot out.
The fact that anti-D3 branes are unstable is also consistent with many other
calculations and expectations about their physics. First, it is known that the perturbative
construction of the anti-D3 brane solution [4, 17] passes some non-trivial checks [5, 1720].
There is no conflict between this and the instability of the anti-branes. Indeed, there are
many black holes and black rings that are unstable, and these solutions make perfect sense
from the point of view of the AdS-CFT correspondence - they are dual to an unstable
phase of the gauge theory, and their instability simply indicates that the dual gauge theory
wants to go to a different ground state.
This instability is also consistent with the fact that one cannot construct a black hole
with anti-D3 brane charges at the bottom of the KS solution [9, 10, 16]: the presence of a
tachyon probably makes such a black hole solution time-dependent. Presumably a similar
phenomenon happens if one perturbs a black hole in AdS5 S5 with a dimension-two
21 + 22 + 23 42 52 62, and it would be interesting to study this system in more
Last but not least, anti-branes have been used to construct solutions dual to microstates
of the D1-D5-p near-extremal black hole [53, 54], and in the probe approximation these
anti-branes appear to be metastable, much like in all other anti-branes studied in this
way [3, 33, 55]. However, on general D1-D5 CFT grounds we expect these microstate
solutions to be unstable, and this instability gives the Hawking radiation rate of the dual
CFT microstate . In the well-known JMaRT solution  this instability is visible from
supergravity because the solutions have an ergo-sphere but no horizon  and the time
scale of the instability is matched perfectly by the emission time from the dual field theory
microstate [59, 60]. Hence, if the instabilities of anti-branes were universal and the
nearextremal microstate solutions constructed by placing negatively-charged supertubes inside
BPS microstates were unstable, this would fit perfectly with what one expects from the
dual D1-D5 CFT and from the general properties of non-extremal black hole microstates.
We would like to thank U. Danielsson, F. Denef, B. Freivogel, I. Klebanov, D. Kutasov,
discussions. I.B. and S.K. are supported in part by the ERC Starting Grant 240210
String-QCD-BH and by the John Templeton Foundation Grant 48222. I.B. is also
supported by a grant from the Foundational Questions Institute (FQXi) Fund, a donor advised
fund of the Silicon Valley Community Foundation on the basis of proposal
FQXi-RFP31321 to the Foundational Questions Institute. This grant was administered by Theiss
Research. The work of M.G. and S.K. is supported in part by the ERC Starting Grant
259133 ObservableString. The work of S.M. is supported by the ERC Advanced Grant
32004 Strings and Gravity. This work was also supported in part by the National
Science Foundation under Grant No. PHYS-1066293 and the hospitality of the Aspen Center
Review of the non-supersymmetric Polchinski-Strassler polarization
In this appendix we review the main aspects of the polarization of D3 branes into
fivebranes studied in  that we use in the analysis in this paper.
1, . . . , 6) corresponds to the SO(6) isometry of the 5-sphere in the dual AdS5 S5 geometry.
gaugino of the vector multiplet, transform in the 4 of SU(4), the covering group of SO(6).
the solution is SO(3) invariant.
On the gravity side giving mass to the fermions corresponds to turning on
nonnormalizable modes of the complex 3-form flux defined as G3 F3
It was first noticed by Girardello, Petrini, Porrati and Zaffaroni (GPPZ)  that this
perturbation of AdS5 S5 leads to a naked singularity in the infrared, caused essentially
by the backreaction of the three-forms. It was realized later by Polchinski and Strassler
S5 at a nonzero value of the AdS5 radial coordinate.
in  that the singularity is resolved via the Myers effect , by the polarization of the
D3 branes that source AdS5 S5 into five-branes that wrap certain 2-spheres inside the
The existence of these polarized branes was first ascertained by considering probe (c, d)
5-branes10 with D3 charge n placed inside a solution sourced by N D3 branes and deformed
with three-form fluxes:
ds2D3 = h1/2dxdx + h1/2 dr2 + r2dsS5 , F5 = (1 + ?10) dh1 dx0 dx1 dx2 dx3 , (A.1)
where h is the warp factor sourced by the N D3 branes and ?10 represents the Hodge dual
in the full ten-dimensional metric ds2D3.
10In our conventions (1, 0) and (0, 1) correspond to NS5 and D5 branes respectively.
One can define the five-brane mass parameter
and introduce complex coordinates zi for the R6 transverse to the D3 branes, such that the
location and orientation of all SO(3)-invariant polarized shells can be parameterized by a
The polarization potential of n D3 branes then takes the following form (we use the
conventions adopted in ):
V(p,q) (z) = V
five-sphere (in the 20 of SO(6)).
where we have omitted higher-order contributions that are subleading when n2
The polarization potential depends on only three complex parameters: the supersymmetric
mass m of the three chiral multiplets, the non-supersymmetric gaugino mass m0 and a
This polarization potential is detailed balanced. Namely, it might have a local
where the quartic, cubic and quadratic terms are of the same order, and hence none of
them can be ignored. Higher-order terms in the 1/n expansion are subleading and can be
Let us discuss the origin of the three terms in the polarization potential:
and as such is always positive. It represents the mass difference between a stack of n
D3 branes dissolved in a 5-brane wrapped on the S2 and the same stack of D3 branes
without the 5-brane. This term does not depend on the mass-deformation parameters,
and its form follows from the fact that the space orthogonal to the original stack of
D3 branes is locally R6 . In particular, the D3 warp factor h drops out in this
term, and hence this term is independent of the location of the D3 branes that source
this warp factor. Hence, this term remains the same in all D3-like geometries of the
The terms cubic in z come from the force exerted by the perturbation three-form
field strengths on the branes. These terms are proportional to m or m0, and can be
computed by plugging the 6-form potentials C6 and B6 (Hodge-dual to C2 and B2)
in the Wess-Zumino action of the five-brane. As shown in , when the solution has
the form (A.1) these 6-forms are completely determined by the AISD perturbation
where ?6 denotes the Hodge dual in the unwrapped six-dimensional space orthogonal
to the D3 branes.11 The equations of motion force this form to be closed and
coand therefore this form is completely determined by the topology of the orthogonal
space and by the UV non-normalizable modes that encode the information about the
mass-deformation parameters m and m0. Note that this is a very powerful result:
when moving the D3 branes, both the three-form G3 and the warp factor h changes,
but the combination of these parameters that enters in the potential of the polarized
The term proportional to n is proportional to the square of the fermion masses
perturbation, and represents the potential felt by a probe D3 in the perturbed background.
The |m|2 and |m0|2 terms come from the backreaction of G3 on the metric, dilaton
and five-form, which will now exert a force on probe D3 branes. The expression of
these terms was derived in  by using supersymmetry and in  by a direct
evaluation of the backreacted solution (the square of the three-form provides a source in
the equations of motion for the trace of orthogonal metric combined with the
dilanon-normalizable mode that is dual to an off-diagonal traceless bilinear bosonic mass
sons source-free) equation on the orthogonal unwrapped space, and so its solution is
also determined completely by the asymptotic boundary conditions in the UV and is
Hence, the SO(3)-invariant polarization potential is completely determined by the three
derive the polarization potential of the localized anti-D3 branes, is that all the terms in
this potential are determined by the UV boundary conditions and do not depend on the
location of the D3 branes that source the background.
factor h. The only terms that might depend on the location of the branes are therefore
those proportional to |m|2 and |m0|2. However, it is easy to see that this is not so: first,
should be a perfect square. Since the first two terms of this potential are independent of
the location of the branes, so should be the term proportional to |m|2. Second, one can see
very easily that the relative coefficient between the |m0|2 and the |m|2 terms must be 1/3.
Indeed, the three fermions of the chiral multiplets (which have mass m) and the gaugino
thus have to enter the potential on equal footing. we say at the beginning of the paragraph:
this argument therefore establishes that all the terms in the potential (3.1) are independent
of the location of the D3 branes.
This observation played a key role in the analysis of , as it allowed to argue that
the polarization potential of several probe D3 branes in the background sourced by many
coincident D3 branes is the same as the one in which the D3 branes that source the
background are themselves polarized into several concentric shells. Hence, the full polarization
potential, (3.1), is given by replacing n in eq. (A.3) by the total number of three-branes,
ND3. This argument made crucial use of the fact that the main interaction between the
various shells comes from the D3 branes that are dissolved in them, and ignored shell-shell
interaction, which is indeed irrelevant in the limits in which the calculation was done.
Our analysis indicates that the same observation is valid for the non-supersymmetric
polarization of anti-D3 branes on the deformed conifold, and also that it is independent
of the space in which the anti-D3 branes sit, as long as at leading-order the geometry
is anti-D3-dominated (A.1). However, there are two important distinctions. First, when
the space transverse to the branes has some compact directions, the polarization in the
channels that are extended along these directions can be affected if the size of the polarized
branes is larger than the size of these directions. Second, this argument can only be used to
calculate the polarization potential along channels where the polarized brane shells do not
touch each other. Hence, it cannot be used to relate the polarization potential of several
probe anti-D3 branes to polarize into an NS5 brane that wraps an S2 inside the S3 at
the bottom of the KS solution in the background sourced by localized anti-D3 branes, to
the corresponding polarization potential in the background sourced by smeared anti-D3
branes, because smearing the anti-branes on the S3 makes the probe shells intersect and
annihilate. However, it can be used to relate the potentials for polarizing into D5 branes
wrapping the contractible S2 in the backgrounds of smeared and localized anti-D3 branes,
because the smearing can be done without the 5-brane shells touching each other, and this
is one of the key facts that enters in our analysis in section 4.
The complex components of the three-form at the North Pole
In this appendix we provide the details of the expansion of the three-form field strengths
around the North Pole of the S3 at the tip of the deformed conifold.
metric around this point and we then find a complex structure for the corresponding flat
six-dimensional space. We then use this parametrization to compute the components of
correspond to the masses m and m0 in the polarization potential.
pendent of the others. However when the branes are smeared inside the polarization plane and the
2-spheres intersect (center) there are new massless degrees of freedom that are not included in the
DBI action and which cause the spheres to merge into cylindrical shells (right).
The deformed conifold parametrization.
We follow the standard convention for the
conifold (see for instance ). The deformed conifold is defined by:
To express the zis in terms of the angular and the radial coordinates one writes:
z3 + iz4 z1 iz2
z1 + iz2 z3 + iz4
W = L1W(0)L2
e 2 0
where L1 and L2 are SU(2) matrices:
This gives the following identifications:
e 21 (+i) cos 1 cos 2 e 2i (1+2) sin 1 sin 2 e 2i (1+2)
sin 1 sin 2 e 2i (1+2) + cos 1 cos 2 e 2i (1+2)
e 21 (+i) cos 1 cos 2 e 2i (1+2) + sin 1 sin 2 e 2i (1+2)
sin 1 sin 2 e 2i (1+2) cos 1 cos 2 e 2i (1+2)
cos 1 sin 2 e 2i (12) sin 1 cos 2 e 2i (21)
sin 1 cos 2 e 2i (12) cos 1 sin 2 e 2i (21)
e 21 (+i) cos 1 sin 2 e 2i (12) sin 1 cos 2 e 2i (21)
+ e 21 (+i) sin 1 cos 2 e 2i (12) cos 1 sin 2 e 2i (21)
Expanding around the North Pole.
yi Im(zi) the deformed conifold definition (B.1) becomes:
When written in terms of xi Re(zi) and
X yi2 = 2
X xiyi = 0 .
rameters (x1, x2, x3, y1, y2, y3) provide a good set of R6 coordinates in the vicinity of the
pole. These branes break the isometry group from SU(2) SU(2) down to an SU(2) which
simultaneously rotates (x1, x2, x3) and (y1, y2, y3). In other words, we are interested in a
for i = 1, 2, 3 .
variables appearing on the right hand side of (B.5):
This gives the parametrization:
Expansion of the 1-forms. The standard basis of 1-forms that diagonalize the T 1,1
By using the expansion (B.7) for the angles, we get to the following results for the 1-forms
near the North Pole:
g3 = 2 (ud + v sin d + cos dw) + O
In terms of the local R6 coordinates we find:
g4 = 2 ( sin dx1 + cos dx2) + O
g3 = 2 ( sin (cos dx1 + sin dx2) + cos dx3) + O
We note that the three (1, 0) forms are:
g4 + iyg1 = 2 ( sin dz1 + cos dz2) + O 2 ,
g5 id = 2 ( cos (cos dz1 + sin dz2) sin dz3) + O
g3 iyg2 = 2 ( sin (cos dz1 + sin dz2) + cos dz3) + O
where zi xi + iyi.
The closed and co-closed form.
Having obtained the explicit parametrization of the
defined in (3.2), from which we can read off the mass parameters that enter in the anti-D3
polarization potential. Using the most general solution with smeared anti-D3 branes at
h1 (?6G3 + iG3) = 4k e2yd g3 g4 + ig1 g2 g5
e2yd g1 g2 + ig3 g4 g5 2eF (g5 + id ) (g1 g3 + g2 g4) .
coordinate. For the smeared anti-D3 solution, the functions that enter in (B.12) have the
We also know (see (4.3) of ) that the equations of motion fix:
If we now plug the expansions (B.10) as well as (B.13) and (B.14) in the expression for
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