We report a systematic study of the stringy interaction between two sets of Dp branes placed parallel at a separation in the presence of two worldvolume fluxes for each set. We focus in this paper on that the two fluxes on one set have the same structure as those on the other set but they in general differ in values, which can be both electric or both magnetic or one electric and one magnetic. We compute the respective stringy interaction amplitude and find that the presence of electric fluxes gives rise to the open string pair production while that of magnetic ones to the open string tachyon mode. The interplay of these two leads to the open string pair production enhancement in certain cases when one flux is electric and the other is magnetic. In particular, we find that this enhancement occurs even when the electric flux and the magnetic one share one common field strength index which is impossible in the one-flux case studied previously by the present author and his collaborator in [17]. This type of enhancement may have realistic physical applications, say, as a means to explore the existence of extra dimensions.
It is noted that a finite Penrose limit for brane probes with non-zero worldvolume fluxes does not generically exist; this is closely related to the observation by Blau et al that for a brane probe the Penrose limit is equivalent to an infinite-tension limit. It is shown that when the limit exists, however, the number of supersymmetries preserved by the probe does not decrease.
We derive and carry out a detailed analysis of the equations of motion of the type IIB D branes in generic supergravity backgrounds with fluxes making account of the worldvolume Born-Infeld gauge field and putting a special emphasis on the structure of the Dirac equation for Dp brane fermionic modes. We present an explicit form of the worldvolume field equations for each of the Dp branes (p=1,3,5,7,9) in the cases in which the Neveu-Schwarz flux and the Ramond-Ramond p-form flux along the Dp-brane worldvolume are zero and the supergravity backgrounds do not necessarily induce the worldvolume B…
Problems of stabilizing moduli of the type--IIB string theory on toroidal orientifolds $\T^6/\Z_2$, in presence of worldvolume fluxes on various D-branes, are considered. For $Z_2$ actions, introducing either O9 or O3 planes, we rule out the possibility of moduli stabilization in a wide class of models with $\mathcal{N}=1$ supersymmetry, characterized by the type of fluxes turned on along D-brane worldvolume. Our results, in particular, imply that Abelian worldvolume fluxes can not by themselves stabilize closed string moduli, in a consistent supersymmtric model, for above orientifold compacti…
E3-instantons that generate non-perturbative superpotentials in IIB N=1 compactifications are more frequent than currently believed. Worldvolume fluxes will typically lift the E3-brane geometric moduli and their fermionic superpartners, leaving only the two required universal fermionic zero-modes. We consistently incorporate SL(2, Z) monodromies and world-volume fluxes in the effective theory of the E3-brane fermions and study the resulting zero-mode spectrum, highlighting the relation between F-theory and perturbative IIB results. This leads us to a IIB derivation of the index for generation …
In this work we obtain classical solutions of the bosonic sector of the supermembrane theory with two-form fluxes associated to a quantized constant $C_{\pm}$ background. This theory satisfies a flux condition on the worldvolume that induces monopoles over it. Classically it is stable as it does not contain string-like spikes with zero energy in distinction with the general case. At quantum level the bosonic membrane has a purely discrete spectrum but the relevance is that the same property holds for its supersymmetric spectrum. We find for this theory spinning membrane solutions, some of them…
We show that the fluxes of the various six-dimensional "gauge" theories are associated to below threshold bound states of D-branes with the NS-5-branes and KK-monopoles which preserve half of bulk supersymmetry. We then present the supergravity solutions that correspond to these bound states. In addition using the worldvolume solitons of IIA and IIB NS-5-branes and KK-monopoles, we investigate the sectors of the "gauge" theories that preserve one quarter of bulk supersymmetry. This leads to a generalization a supergravity solution which has the interpretation of two intersecting NS-5-branes at…
We explore various properties of interaction between D$_p$ and D$_{p'}$ with each carrying a worldvolume flux and with the $p'$-branes placed along $p'$ spatial worldvolume directions of the p-branes at a separation when $p - p' = 2$. Carefully analyzing the annulus amplitudes calculated via the boundary state approach, we find that many features of amplitudes remain similar to those studied when $p = p'$ such as the nature of force on the brane separation, the onset of various instabilities when the brane-separation is on the order of string scale and the occurrence of pair production of open…
It has been conjectured that a pair of D5 - anti D5 branes wrapped on some non-trivial two cycle of a Calabi-Yau manifold becomes a stable BPS D3 brane in the presence of a very large B field and magnetic fluxes on their worldvolumes. We discuss this by considering the non-commutative field theory on the worldvolume of the pair of branes whose field multiplication is made with respect to two different * products due to the presence of different F fields on the two branes. The tachyonic field becomes massless for a specific choice of the magnetic fluxes and it allows a trivial solution. Our dis…
We consider D-branes in group manifolds, from the point of view of open strings and using the Born-Infeld action on the brane worldvolume. D-branes correspond to certain integral (twined) conjugacy classes. We explain the integrality condition on the conjugacy classes in both approaches. In the Born-Infeld description, the D-brane worldvolume is stabilized against shrinking by a subtle interplay of quantized U(1) fluxes and the non-triviality of the B-field.
The kappa--invariant worldvolume action for the NS5--brane in a D=10 type IIA supergravity background is obtained by carrying out the dimensional reduction of the M5--brane action.
The understanding of the fermionic sector of the worldvolume D-brane dynamics on a general background with fluxes is crucial in several branches of string theory, like for example the study of nonperturbative effects or the construction of realistic models living on D-branes. In this paper we derive a new simple Dirac-like form for the bilinear fermionic action for any Dp-brane in any supergravity background, which generalizes the usual Dirac action valid in absence of fluxes. A nonzero world-volume field strength deforms the usual Dirac operator in the action to a generalized non-canonical on…
We describe a topological effect on configurations of D-branes in the presence of NS-NS and RR field strength fluxes. The fluxes induce the appearance of chiral anomalies on lower dimensional submanifolds of the D-brane worldvolume. This anomaly is not associated to a dynamical chiral fermion degree of freedom, but rather should be regarded as an explicit flux-induced anomalous term (Wess-Zumino term) in the action. The anomaly is cancelled by an inflow mechanism, which exploits the fact that fluxes can act as sources of RR fields. We discuss several applications of this flux-induced anomaly; …
We examine magnetic and electric near horizon regions of maximally supersymmetric D-brane and NS5-brane bound states and find transformations between near horizon regions with worldvolume dual magnetic and electric fluxes. These point to dual formulations of NCYM, NCOS and OD$p$ theories in the limit of weak coupling and large spatial or temporal non-commutativity length scale in terms of weakly coupled theories with fixed worldvolume dual non-commutativity based on open D-branes. We also examine the strong coupling behavior of the open D-brane theories and propose a unified web of dualities i…
It is shown that a IIA superstring carrying D0-brane charge can be `blown-up', in a {\it Minkowski vacuum} background, to a (1/4)-supersymmetric tubular D2-brane, supported against collapse by the angular momentum generated by crossed electric and magnetic Born-Infeld fields. This `supertube' can be viewed as a worldvolume realization of the sigma-model Q-lump.
We consider discrete K-theory tadpole cancellation conditions in type IIB orientifolds with magnetised 7-branes. Cancellation of K-theory charge constrains the choices of world-volume magnetic fluxes on the latter. We describe the F-/M-theory lift of these configurations, where 7-branes are encoded in the geometry of an elliptic fibration, and their magnetic quanta correspond to supergravity 4-form field strength fluxes. In a K3 compactification example, we show that standard quantization of 4-form fluxes as integer cohomology classes in K3 automatically implies the K-theory charge cancellatio…
We present a simple example of a supersymmetric attractor mechanism in the purely open string context of D-branes embedded in curved space-time. Our example involves a class of D3-branes embedded in the 2-charge D1-D5 background of type IIB whose worldvolume contains a 2-sphere. Turning on worldvolume fluxes, these branes carry induced (p,q) string charges. Supersymmetric configurations display a flow of the open string moduli towards an attractor solution independent of their asymptotics. The equations governing this mechanism closely resemble the attractor flow equations for supersymmetric b…
In three spacetime dimensions the worldvolume of a magnetic source is a single point, an event. We make the event dynamical by regarding it as the imprint of a flux-carrying particle impinging from an extra dimension. This can be generalized to higher spacetime dimensions and to extended events. We exhibit universal observable consequences of the existence of events and argue that events are as important as particles or branes. We explain how events arise on the worldvolume of membranes in M theory, and in a Josephson junction in superconductivity.
We show the relation between three non trivial sectors of M2-brane theory formulated in the LCG connected among them by canonical transformations. These sectors correspond to the supermembrane theory formulated on a $M_9\times T^2$ on three different constant three-form backgrounds: M2-brane with constant $C_{-}$, M2-brane with constant $C_{\pm}$ and M2-brane with a generic constant $C_3$ denoted as CM2-brane. The first two exhibit a purely discrete supersymmetric spectrum once the central charge condition, or equivalently, the corresponding flux condition has been turned on. The CM2-brane is …
We here report a possibility of detecting the open string pair production from the system of a D3 brane, taken as our own (1 + 3)-dimensional world and carrying its worldvolume collinear electric and magnetic fluxes, and a nearby D-string, placed parallel at a separation in the directions transverse to both branes.
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 $2 \le p \le 8$ in both type IIA (when $p$ is even) and type IIB (when $p$ is odd) string theories. As in $p = 1$ case, these bound states can each be interpreted as $n$ Dp-branes carrying m units of quantized constant electric field. In particul…
We compute the closed-string cylinder amplitude between one Dp brane and the other Dp$\prime$ brane, placed parallel at a separation, with each carrying a general constant worldvolume flux and with $p - p' = 0, 2, 4, 6$ and $p \le 6$. For the $p = p'$, we show that the main part of the amplitude for $p = p' < 5$ is a special case of that for $p = p' = 5$ or $6$ case. For all other $p - p' = 2, 4, 6$ cases, we show that the amplitude is just a special case of the corresponding one for $p = p'$ case. Combining both, we obtain the general formula for the amplitude, which is valid for each of the …
We discuss general supersymmetric brane configurations in flux backgrounds of string and M-theory and derive a necessary condition for the worldvolume theory to be supersymmetric on a given curved manifold. This condition resembles very much the conditions found from coupling a supersymmetric field theory to off-shell supergravity but can be derived in any dimension and for up to sixteen supercharges. Apart from the topological twist, all couplings appearing in the supersymmetry condition are linked to fluxes in the bulk. We explicitly derive the condition for D3-, M2- and M5-branes, in which …
Wilson lines in N=4SYM can be computed in terms of branes carrying electric flux, i.e. F-strings dissolved in their worldvolumes. It is then natural to think that those configurations are the effective description of strings expanding due to dielectric effect to D-branes. In this note we explicitly show this for a class of such configurations, namely those dual to Wilson lines either in the symmetric or in the antisymmetric tensor product of fundamentals.
Motivated by a recent observation that the LLM geometries admit 1/4-BPS M5-brane probes with worldvolume AdS3 X Σ_2 X S1 preserving the R-symmetry, we initiate a classification of the most general AdS3 X S2 geometries in M-theory. We retain all field strengths consistent with symmetry and derive the torsion conditions for M_6 in terms of two linearly independent spinors. Surprisingly, we identify three Killing directions for M_6, but only two of these generate isometries of the overall ansatz. We show that the existence of this third direction depends on the norm of the spinors. Then, speciali…
We extend the amplitude calculations of \cite{Lu:2009yx} to exhaust the remaining cases for which one set of D$_p$ 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 ins…
In analogy to the Schwinger pair production in QED, there exists also the so-called open string pair production for a system of two Dp branes, placed parallel at a separation, with at least one brane carrying a worldvolume electric flux, in Type II string theories. There is however no such pair production if an isolated Dp brane carrying an electric flux is considered. The produced open strings are directly related to the brane separation, therefore to the extra-dimensions if taken from the viewpoint of a brane observer. This pair production can be greatly enhanced if one Dp brane carries also…
We consider compactifications of type I supergravity on manifolds with SU(3) structure, in the presence of RR fluxes and magnetized D9-branes, and analyze the generalized Dirac and Laplace-Beltrami operators associated to the D9-brane worldvolume fields. These compactifications are T-dual to standard type IIB toroidal orientifolds with NSNS and RR 3-form fluxes and D3/D7 branes. By using techniques of representation theory and harmonic analysis, the spectrum of open string wavefunctions can be computed for Lie groups and their quotients, as we illustrate with explicit twisted tori examples. We…
We consider flux compactifications of heterotic string theory in the presence of fermionic condensates on M_{1,2} times X_7 with both factors carrying a Killing spinor. In other words, M_{1,2} is either de Sitter, anti-de Sitter or Minkowski, and X_7 possesses a nearly parallel G_2-structure or has G_2-holonomy. We solve the complete set of field equations and the Bianchi identity to order alpha'. The latter is satisfied via a non-standard embedding by choosing the gauge field to be a G_2-instanton. It is shown that none of the solutions to the field equations is supersymmetric.
We show that the $D=11$ Supermembrane theory (M2-brane) compactified on a $M_9 \times T^2$ target space, with constant fluxes $C_{\pm}$ naturally incorporates the geometrical structure of a twisted torus. We extend the M2-brane theory to a formulation on a twisted torus bundle. It is consistently fibered over the world volume of the M2-brane. It can also be interpreted as a torus bundle with a nontrivial $U(1)$ connection associated to the fluxes. The structure group $G$ is the area preserving diffeomorphisms. The torus bundle is defined in terms of the monodromy associated to the isotopy clas…
The standard extremal p-brane solutions in supergravity are known to allow for a generalisation which consists of adding a linear dependence on the world-volume coordinates to the usual harmonic function. In this note we demonstrate that remarkably this generalisation goes through in exactly the same way for p-branes with fluxes added to it that correspond to fractional p-branes. We relate this to warped orientifold compactifications by trading the Dp-branes for Op-planes that solve the RR tadpole condition. This allows us to interpret the worldvolume dependence as due to lower-dimensional sca…
We start with a 2-charge D1-D5 BPS geometry that has the shape of a ring; this geometry is regular everywhere. In the dual CFT there exists a perturbation that creates one unit of excitation for left movers, and thus adds one unit of momentum P. This implies that there exists a corresponding normalizable perturbation on the near-ring D1-D5 geometry. We find this perturbation, and observe that it is smooth everywhere. We thus find an example of `hair' for the black ring carrying three charges -- D1, D5 and one unit of P. The near-ring geometry of the D1-D5 supertube can be dualized to a D6 bran…
We construct a Poisson algebra of brane currents from a QP-manifold (alias symplectic $L_\infty$-algebroid), and show their Poisson brackets take a universal geometric form. This generalises a result of Alekseev and Strobl on string currents and generalised geometry to include branes with worldvolume gauge fields, such as the D3 and M5. Our result yields a universal expression for the 't Hooft anomaly that afflicts isometries in the presence of fluxes. We determine the current algebra in terms of (exceptional) generalised geometry, and show that the tensor hierarchy gives rise to a brane curre…
We study the low energy dynamics of a single Dp-brane carrying sufcient large number of D0-brane charges in type IIA theory. We assume the D-brane topology to be $R \times \mathcal{M}_{2n} $ , where $\mathcal{M}_{2n}$ is a closed manifold admitting a symplectic structure. We propose a new gauge fixing condition which eliminates the spatial gauge fluctuations on the Dp-brane. Using a conventional regularization method, one finds that the dynamics is characterized by D0-brane matrix description when the density of D0-branes is large enough. We also calculate the leading order interactions betwee…
We systematically study the spectrum of excitations and the one-loop determinant of holographic Wilson loop operators in antisymmetric representations of $\mathcal{N}=4$ supersymmetric Yang-Mills theory. Holographically, these operators are described by D5-branes carrying electric flux and wrapping an $S^4 \subset S^5$ in the $AdS_5\times S^5$ bulk background. We derive the dynamics of both bosonic and fermionic excitations for such D5-branes. A particularly important configuration in this class is the D5-brane with $AdS_2\times S^4$ worldvolume and $k$ units of electric flux, which is dual to…
We study the effect of adding lower dimensional brane charges to the 't Hooft monopole, di-baryon and baryon vertex configurations in AdS_4 x CP^3. We show that these configurations capture the background fluxes in a way that depends on the induced charges, requiring additional fundamental strings to cancel the worldvolume tadpoles. The dynamics reveal that the charges must lie inside some interval, a situation familiar from the baryon vertex in AdS_5 x S^5 with charges. For the baryon vertex and the di-baryon the number of fundamental strings must also lie inside an allowed interval. Some ide…
We study the Type IIA NS five-brane wrapped on a Calabi-Yau manifold X in a double-scaled decoupling limit. We calculate the euclidean partition function in the presence of a flat RR 3-form field. The classical contribution is given by a sum over fluxes of the self-dual tensor field which reduces to a theta-function. The quantum contributions are computed using a T-dual IIB background where the five-branes are replaced by an ALE singularity. Using the supergravity effective action we find that the loop corrections to the free energy are given by B-model topological string amplitudes. This seem…
We study the effect of adding lower dimensional brane charges to the 't Hooft monopole, di-baryon and baryon vertex configurations in $AdS_4 \times \mathbb{P}^3$. We show that these configurations capture the background fluxes in a way that depends on the induced charges, and therefore, require additional fundamental strings in order to cancel the worldvolume tadpoles. The study of the dynamics reveals that the charges must lie inside some interval in order to find well defined configurations, a situation familiar from the baryon vertex in $AdS_5 \times S^5$ with charges. For the baryon vertex…
We consider a sigma model formulation of open string theory with boundary fermions carrying Chan-Paton charges at the string ends. This formalism is particularly suitable for studying world-volume potentials on D-branes. We perform explicit two-loop sigma model computations of the potential T-dual to the non-abelian Born-Infeld action. We also discuss the world-volume couplings of NS fluxes which are responsible for Myers' dielectric effect.
In the holographic framework, a half BPS Wilson loop in ${\cal N}=4$ supersymmetric Yang-Mills in the fundamental, symmetric or antisymmetric representation of SU(N), is best described by a fundamental string, a D3 brane or a D5 brane with fluxes in their worldvolumes, respectively. We derive the spectrum of excitations of such D3 brane in $AdS_5\times S^5$ explicitly, considering its action in both the bosonic and the fermionic sectors, and demonstrate that it is organized according to short multiplets of the supergroup $OSp(4^*|4)$. We also show that the modes of the fundamental string form …
We investigate a holographic description of k-strings in higher representations via D5 branes with worldvolume fluxes. The D-brane configurations are embedded in supergravity backgrounds dual to confining field theories in 3 and 4 dimensions. We compute the tensions and find qualitative agreement for the totally symmetric and totally anti-symmetric representations with the results of other methods such as lattice as well as the Hamiltonian approach of Karabali and Nair. A one-loop computation on the D-brane configurations yields the Luescher term and allows us to confirm a previously proposed …
An interesting consequence of string dualities is that they reveal situations where the geometry of a string background appears to be globally ill-defined, a phenomenon usually referred to as non-geometry. On the other hand, string theory contains extended objects with non-trivial monodromy around them, often dubbed defect or exotic branes in co-dimension two. We determine and examine the worldvolume actions and the couplings of certain such branes. In particular, based on specific chains of T and S-dualities, we derive the DBI and WZ actions, which describe the dynamics of type IIB fivebranes…
We study the effect of RR and NSNS 3-form fluxes on the effective action of the worldvolume fields of Type IIB D7/D3-brane configurations. The D7-branes wrap 4-cycles on a local Calabi-Yau geometry. This is an extension of previous work on hep-th/0311241, where a similar analysis was applied to the case of D3-branes. Our present analysis is based on the D7- and D3-brane Dirac-Born-Infeld and Chern-Simons actions, and makes full use of the R-symmetries of the system, which allow us to compute explicitly results for the fields lying at the D3-D7 intersections. A number of interesting new propert…
We elucidate some properties of the relation between two T-dual systems in tori, branes at angles and branes wrapping the whole torus carrying fluxes. We analyze different features of these systems: charges, low energy spectrum, tadpole cancellation, symmetry groups, ... and the correspondence between the two viewpoints. Particular attention is paid to supersymmetry and stability conditions. While on the branes at angles side stability and supersymmetry can be expressed as conditions on the angles between the two branes at the intersection, on the dual side supersymmetry has to do with a corre…
We study the open string pair production between two D3 branes, which will give rise to similar effect as Schwinger pair production for observers on one of the D3 branes. The D3 branes are placed parallel at a distance, and they are carrying world-volume electromagnetic fluxes that takes general form. We derive the pair production rate by computing the interaction amplitude between the D3 branes. We discussed how to maximize the pair production rate in this general case. We also mentioned that the general result can be used to describe other system such as D3-D1, where the pair production is u…
We consider a holographic description of a system of strongly coupled fermions in 2+1 dimensions based on a D7-brane probe in the background of D3-branes, and construct stable embeddings by turning on worldvolume fluxes. We study the system at finite temperature and charge density, and in the presence of a background magnetic field. We show that Minkowski-like embeddings that terminate above the horizon describe a family of quantum Hall states with filling fractions that are parameterized by a single discrete parameter. The quantization of the Hall conductivity is a direct consequence of the t…
When a color superconductor of high density QCD is rotating, superfluid vortices are inevitably created along the rotation axis. In the color-flavor locked phase realized at the asymptotically large chemical potential, there appear non-Abelian vortices carrying both circulations of superfluid and color magnetic fluxes. A family of solutions has a degeneracy characterized by the Nambu-Goldtone modes CP2, associated with the color-flavor locked symmetry spontaneously broken in the vicinity of the vortex. In this paper, we study electromagnetic coupling of the non-Abelian vortices and find that t…
Recent studies by one of the present authors along with his collaborators in [1-4] show that there exist the so-called open string pair production for a possible simplest system of two Dp branes, placed parallel at a separation and with each carrying different electric flux, in Type II superstring theories. Further this pair production can be greatly enhanced when a magnetic flux, sharing no common field strength index with the electric one, is added, implying then $p \ge 3$. Given this, one may wonder if further enhancement can be achieved by adding more magnetic flux(es) in a similar fashion…
We analyze the dynamics of neutral black rings in Taub-NUT spaces and their relation to systems of D0 and D6 branes in the supergravity approximation. We employ several recent techniques, both perturbative and exact, to construct solutions in which thermal excitations of the D0-branes can be turned on or off, and the D6-brane can have $B$-fluxes turned on or off in its worldvolume. By explicit calculation of the interaction energy between the D0 and D6 branes, we can study equilibrium configurations and their stability. We find that although D0 and D6 branes (in the absence of $B$ fields, and …
Classical solutions describing strings endowed with an electric charge and carrying a constant electromagnetic current are constructed within the bosonic sector of the Electroweak Theory. For any given ratio of the Higgs boson mass to W boson mass and for any Weinberg's angle, these strings comprise a family that can be parameterized by values of the current through their cross section, $I_3$, by their electric charge per unit string length, $I_0$, and by two integers. These parameters determine the electromagnetic and Z fluxes, as well as the angular momentum and momentum densities of the str…
For a massive scalar field with a general curvature coupling parameter, we investigate the finite temperature contributions to the Hadamard function and to the charge and current densities in the geometry of a magnetic flux carrying generalized cosmic string embedded in $(D+1)$-dimensional locally AdS spacetime with a compactified spatial dimension. For $D=4$, the geometry on the AdS boundary, in the context of the AdS/CFT duality, corresponds to a cosmic string as a linear defect, compactified along its axis. In contrast to the case of the Minkowski bulk, the upper bound on the chemical poten…
